Special methods of analysis. 1 application. Special methods of analysis. 1 application.

Special methods of analysis. 1 application.

There are many publications on food analysis, and in some of them is given details of methods that can be employed in the confectionery business. All manufacturers of chocolate and confectionery products must be familiar with organizations such as The International Office of Cocoa and Chocolate (IOCC), 172, Avenue de Cortenbergh, 1040 Bruxelles, Belgium, and The International Sugar Confectionery Manufacturers' Association (ISCMA), 194, rue de Rivoli, 75001 Paris, France.
Both of these organizations collect all its members every five years, and monitor all aspects of the industry.
IOSS publishes the "official" methods of analysis, which are regularly updated and are accepted worldwide as the standard. Also publishes periodic bulletins that describe the activities of these organizations.
Industry-specific analytical methods described in the manufacturer brochures. Industry magazines often contain articles relating to the application of these techniques and the value of the results.
Analytical procedures, when necessary, mentioned in the previous chapters. Some of the methods listed below are taken from the second edition of this book, and complemented, where it was necessary materials relevant to the modern level.
Particle size
The size of the particles of cocoa, chocolate and confectionery products - this is a very important characteristic. It is important for sensory perception, and for industrial processes.
The smoothness of the chocolate sensation on the palate due to the lack of large sugar and cocoa particles. Similarly, in the case of lipsticks. The cocoa powder particle size determines the properties of their suspension in a liquid, such as milk and water. The particle size distribution (i.e., the proportion of particles of different sizes) is important from an economic standpoint.
In the chocolate using cacao butter to obtain a given flow due to a very small fraction of particles. Because of greater total surface area they require more cocoa butter to their "wetting".
Differences particles
Particles of different chocolate and other confectionery products are significantly different in appearance, shape and size.
When examined under a microscope it can be seen that the cocoa particles have an irregular shape, but have no sharp edges and a different color from a clear, light brown to reddish brown and dark brown opaque.
In dark chocolate the cocoa particles are similar, but less noticeable due to the presence of sugar. Sugar crystals are easily visible as a bright plate generally irregularly shaped because they are crushed during grinding.
Milk chocolate contains cocoa particles, sugar crystals, and milk solids, but if made of milk chocolate crumb, only one kind of visible particles. This dry residue units of milk, sugar and cocoa mass that were formed during the process of formation of crumbs in the final crystallization and drying. These conglomerates are destroyed during the pulverizing but not separated into its component particles.
These units have a light brown color, and some of them can be seen linked sugar crystals and cocoa particles.
The lactic crumb production is important to ensure that the sugar crystals formed in the crystallization step are small and under a microscope units separated by a chemical fixative solution to the sugar crystals can be measured independently. Milk chocolate crumb made from dairy, milk powder particles are clearly visible as pale yellow separate irregularly shaped spots.
The fondant particles are only visible sugar crystals, and since most of them grew without any syrup of interference, they generally have a cubic shape under a microscope and have a very regular shape.
There is a difference between a freshly prepared basic lipstick and a lipstick that has been re-melted and molded into a molding starch. In re-melted lipstick, a part of the crystals is large due to growth in the melting and casting stages, and the remaining crystals are small, as in "basic lipstick". In "basic lipstick," too, large crystals may be found due to poor whipping and cooling during production, and this is discussed in the section "Production of lipstick." The distribution of the size of sugar crystals in lipstick strongly affects the feeling of uniformity in the mouth.
Approximate sizes of particles which may be present in these products are shown in Table. P1. These values ​​- "medium to coarse particles".
Basic product The finished product

Particle size, microns
grated cocoa

The size of the cocoa particles



Cocoa superfine grinding or manufacture of chocolate

100

Cocoa powder for making beverages 200

chocolate temnы
The size of the cocoa particles



High-quality chocolate for direct consumption or high glaze 30-50

Chocolate for the average quality of the glaze 75-100

The size of sugar crystals



High-quality chocolate for direct consumption or high glaze 25-35

Chocolate for the average quality of the glaze 50

milk chocolate
Size crumbs units



High-quality chocolate for direct consumption 35

Chocolate for the average quality of the glaze 50

fondant




"Basic lipstick" of the car

10-15

Lipstick cast (Assorted)

25-30

It should be understood that these data can not be compared with the readings of a micrometer (cm. Below).
Methods for determination
Methods for determination of particle sizes can be divided into the following groups:
  1. Using a micrometer, and modifications.
  2. Microscopic, including computer scan.
  3. Wet sieve analysis, water or oil solvent.
  4. Precipitation.
  5. Electronic counting, using a Coulter Counter and laser beam.
MIKROMETR
For many years, the standard micrometer was used more than any other instrument for the determination of particle size chocolate paste after the rolling machine.
The method uses a small number of finished paste mixed with an equal amount of an oil. A drop of the mixture is placed on the bottom of the metertion surface mic, sponges pull together using a spring-loaded knob until the movement is stopped. Next, read the testimony of a micrometer scale.
The resulting number is not a particle size and does not take into account their shape. It is most likely that some large crystals of sugar will be destroyed during this measurement. The result obtained in the hands of a qualified specialist is indicative, but actually represents the thickness of a layer of particles compressed between the jaws of a micrometer with a standard force. The weakness of this method lies in the fact that the result is influenced by the variety of micrometers, the individual differences of people who use them, the size of the sample, and the fact that the method does not provide accurate information about the actual particle sizes or the content of particles of different sizes.
Achievement of recent years is the creation of an electronic micrometer in which sponges are larger and shifted to determine the exact pressure. The device gives a digital readout, but that number has the same meaning. Features micrometer method as a means of controlling the grinding process required for research aimed at improving the results.
MetriScope
This unit was created in 1958, the Lockwood (Lockwood) from Cadbury Research Laboratories and is the original mechanical device to measure the effectiveness of chocolate or cocoa grinding. The method is actually improved by a micrometer and it is used for measurements of much larger sample. For more information about this tool can be obtained from the Confectionery Division Research Laboratories, Cadbury / Schweppes Ltd., Boumville, Birmingham, England.
The principle of the method is based on the fact that the chocolate film or suspёnzii, particle size is to be measured, supports the nest steel cone "stopper".
"Jam" and the nest have a bevel exactly one to ten. The film of sugar and cocoa particles in a raises plug gap to a height of twenty times the thickness of the film due to the bevel. The projecting part of the plug is accurately measured by a micrometer and this value can be associated with the average size of large particles or chocolate suspension.
Metriscope works automatically and gives some indications repeated in a short time. The instrument used 28,4 g sample is dispersed in 142 letsi- tinizirovannogo g of cocoa butter, which gives a much more significant result than that which is obtained with a very small sample used for the measurement of the micrometer.
Fig. P1 is a schematic representation of the sample and the socket, and Fig. P2 and PZ shows how the machine operates at different factories.
25.1
25.2 Fig. P2- Metriscope - Front View
25.3 Fig. PP. MetriScope - Back view
method for determination
Detectable materials. Pasta after fine grinding, the chocolate after conching machine, ready chocolate suspension.
Necessary equipment. Meґtsore, electric vibratory mixer measurement 5 fluid ounces (0,15 liters) to cocoa butter, the drawer 1 ounce (28,35 g) (for paste after grinding), stainless steel vessel of about 10 fluid ounces (0,3 liters), a spatula Oven supporting 45 ° C.
Cocoa oil dispersion. This cocoa butter in which dissolved 0,25% soy lecithin.
Preparation of samples for testing. One ounce chopped paste is measured using the "dispenser" chocolate cylinder placed on a vibrating mixer perforated disk (Uіgo-tіheg) and mixed in 1 min. with 5 fluid ounces (150 mL) cocoa butter, containing 0,25% of lecithin. Thereafter, the sample is ready for an immediate measurement.
Other materials are typically scanned in small cups are weighed, mixed with a small portion of 5 fluid ounces (150 ml) cocoa butter with a spatula and then transferred to a stainless steel container for mixing.
Working with MetriScope. The heater before using the device is switched on 2 hours to make sure that the device will work with the liquid cocoa butter. Operating temperature range is up to 40 45 ° C, the temperature can be maintained automatically. When it is necessary to perform measurements using at
boron engine include cocoa butter is passed through a wire mesh sieve in the hopper, the handle is moved to «Test» (Test), and the oil begins to fill the inner groove. Any excess oil flowing into the inner groove flows into the outer recess, which is supplied from the collecting tank at the bottom.
From this moment the device works completely automatically, the cork rises and falls so that some cocoa butter remains between the surfaces of the cork and the socket. The vertical rod is released, and the reading on the dial scale serves as an indicator of the thickness of the film. This operation is repeated every 20 s, and after 3-4 full cycles, the inner groove must be empty. For cocoa butter, the reading on the scale should be 25 or less, and when this value is reached, the test slurry is fed inward through a wire mesh sieve. When the internal recess is full, the control knob is rotated to "Waste" and the remainder of the sample enters the storage tank. The first reading on a circular scale is discarded, and the average of the next three measurements is recorded as a result of the instrument measurements. The measurements are carried out in tens of microns.
instrument calibration. To make sure that all instruments give the same indication in the operating range (30-150), standard chocolate comes from the central laboratory with a known metric scope value. Standard chocolate is made, as mentioned above, and the scale of the device is set to the desired position. To do this, release the bolt from the rear and move the scale higher or lower in the rack until the required reading is reached, then tighten the bolt. A small final setting can be made by turning the scale in front, but this setting should not exceed 2-3 division. This operation is performed with the zero adjustment removed. Then the device is started, and the rod should set the scale to a negative reading of about 10 units. Then, the zero control is set in place, so that the prism locks the outer ring of the dial, and the adjustment screw is set so that the scale pointer returns to zero after each measurement. The correctness of the readings of the device is checked daily by scientific personnel (metrologists) and the adjustment by factory employees is not required.
A standard mixture of chocolate and cocoa butter. Two ounces of a chocolate cup was weighed, and mixed with melted 0,3 liters of cocoa butter, and the mixture was poured into a stoppered bottle with a label. This mixture is stored in the device ready for testing on a standard sample. This test is performed, carefully shaking the contents of the bottle and pouring about 1 fluid ounce (30 ml) into the inner groove of the device.
MICROSCOPES
Measurements of sugar crystals and cocoa particles in the initial stage of grinding control performed by standard microscope equipped with transparent eyepiece and scales in a table for the mechanical fixing of the slide with the specimen. Mechanical table allow to investigate methodically material on the slide and the particles were measured using the scale in the eyepiece.
The microscopic method was very tiring and caused eyestrain during long periods of work, but, despite this, it has been used for many years. Hand-held microscopes basically changed projection microscope, the structure of which also greatly improved, especially in terms of the brightness and size of the viewing screen.
Projection microscope shown in Fig. P4. This device is not released, but the figure illustrates the principle of operation that can be applied. Lighting made a powerful xenon lamp, and particle image projected through the lens of a mirror, from which it is reflected in the ten-screen.
The primary objective of the microscope has a small capacity, but with the help of a lever to impose additional lens in the middle of the screen appear larger image. The image given by this device, it turns bright enough that allows measuring in dim daylight. On the screen creates a lattice, which is calibrated for the simple measurement of the particle.
Microscopic measurements are empirical, and their value depends to some extent on the exact method of preparation and systematic drug particle measurement method. With the help of the described system are measured only large particles (10-50 microns). This is usually acceptable for the control of grinding equipment and the production of lipstick.
25.4Fig. P.4. projection microscope
a. Look-ekrand. g. Fine tuning
b. Casing h. The lamp and the condenser
c. Doublet lens to. Fan
d. Subject stolikt. m. Mirror (swing projection on the screen)
e. Condenser
f. Preset n. Wall screen
Company Elcometer Instruments Ltd., Manchester, England
Other methods used to measure the very small particles and size distribution (see. below).
It is often said that one of the advantages of microscopic method is that the particles are "visible", while in other methods - is not present. For many products, this qualitative aspect is a big advantage.
Microscopic measurement techniques. Here are some simple practices. Specific details can be changed as convenient to the user.
grated cocoa. Sample preparation. A representative sample is obtained from refining rollers and mix well. In the case of cocoa liquor larger particles often settle after exposure, and if the measurement is not carried out once the product should be brought to the desired condition (temper) and mold.
Preparation of microscopic sample. The amount of product used in the slide, is determined by x 5 2,5 cm stainless steel plate and 1,2 mm. The plate has a central hole diameter 3 mm.
The plate was placed on a glass slide and a hole in it is filled with a solid or pasty product with a scalpel blade. The excess product is removed by conducting a knife blade over the hole. Product pushed blunt metal rod which fits snugly into the hole. The lozenge of the product placed in the center of the slide.
To the ground product one drop of liquid oil from the micropipette is added, on which the required amount is indicated. For a larger grinding product, a little more oil is required. The slide is heated and the oil and product are mixed with the tip of the scalpel so that the mixture remains within a circle of less than 2,5 cm in diameter. A small amount of oily mixture at the end of the scalpel is neglected, so it should be minimal. After careful mixing in a spot with a diameter of 2,2 cm, the cover glass is placed on top and it is allowed to sink under its own weight. The pressure should not be applied, and the amount of oil used must be sufficient to cover the cover glass without exiting its edges.
It is important that the material remains on the slide. These instructions should be strictly adhered to so that the drugs have a standard density.
Measurement using a projection microscope. The slide is placed on the microscope stage and the image is focused on the screen. First drug methodically investigated to determine the uniformity of the particle size distribution and to estimate approximately the size of large particles. drug then tested a second time, measure and record the dimensions of the larger particles.
After performing measurements 10-15 can easily determine whether the results are representative of the large majority of the particles on the slide. Then takes the average of the first ten results.
The particle size of the chocolate, roll refining after the paste and cocoa in milk crumb. To determine the particle size of the cocoa in the dark and milk chocolate paste after refining rollers or dairy products is necessary to prepare the flakes so that the density of the cocoa particles on slides was the same as in the cocoa mass measurements. If this is not done, the results are strictly not comparable. stainless steel plates with larger holes and pins needed to account for the chocolate liquor in chocolate.
Chocolate crumb composition vary somewhat, but examples of the content in cocoa are listed below (in%):
dark chocolate for eating 30
milk chocolate for eating 11
Milk paste after grinding in the mill 13
milk crumb 14
Calculation of the rod and the hole size must be performed in accordance with the recipe.
In the case of breast crumb best necessary quantity weighed (approximately 15 mg) at predmetnoesteklo, then the product must be mitigated in order to make it possible to manufacture the drug. This can be done using a medium consisting of ethylene glycol saturated with ammonia or dichlorohydrin.
Measurement of particles on a microscope slide is performed by the same procedure as that for cocoa liquor.
Crystals sugar lumps and crumbs
The method of manufacture of preparations similar to that used to measure the cocoa particles, except that the oil is colored in red with a fat-soluble dye. The density of the crystals and aggregates on a slide such that usually does not require a correction that takes into account the sugar content in chocolate.
The first study of the drug may show the presence of a small amount of "wrong" crystals, the size of which is much higher than the average value of large crystals. Usually they are not taken into account in the measurements.
The dark chocolate sugar crystals have a clearly defined path and they are easy to measure, but in milk chocolate and pastes necessary to measure units of ground crumb, are more difficult to discern. Sometimes some grinding sugar crystals are separated from aggregates, and they are smaller in size aggregates.
When manufacturing chips, crystallization occurred too slowly, sugar crystals grow too large and aggregates are formed containing these large crystals. They make it difficult to grind, and the yield decreases.
Measurement of sugar crystals in crumbs performed using fluid from the dichlorohydrin or glycol, but this measurement is rarely needed when manufacturers chocolate crumb made their own, so they have to check the size of sugar crystals on the kneading step (cm. "Milk crumb production").
In milk chocolate manufactured with dry milk, sugar crystals visible as a dark chocolate. Particles of powdered milk and yellow light have an irregular shape.
fondant. Already mentioned, that can be fondant crystals whose dimensions lie in the two ranges due to bad conditions in the whipping machine for lipstick or poor melting. Large crystals can also occur due to inclusions of waste for reuse, but now it is rarely done. Turning waste is best done by recycling them in syrup and discoloring (see. "Regeneration").
Preparation of the drug. The hole in the plate, similar to that used for cocoa liquor, stuffed lipstick. Then lipstick out of the hole is placed on a glass slide, where it is mixed with the glycerol medium and painted in red or green. The slide then necessary to investigate immediately, it can not be heated, as can happen formation of some crystals from solution.
Well cooked main lipstick should have a size distribution similar to the following: a very large number of crystals 10 15 micron and micron; crystals of 20 microns should be absent. The average size of the crystal should be 12,5 microns.
Measurements fondant chocolates molded casting. This is a difficult task, if the inspection of several areas shows that there are two different size ranges.
This method provides a count of crystals in large sizes and recording ranges as shown in Table. P2. The average size "larger crystals" must then be estimated as follows:
Example 1 28 microns
Example 2 20 microns
Example 3 40 microns
P2 Table. Lipstick candy molded casting (Assorted)


Size, mm


Less than 20

25

30 35

40

45

Example 1











Number of crystals Example 2
Number of crystals Example 3
A large number of

A large number of


XXX

XXXX

XXX XXX X

XXX

XXX

Number of crystals

A large number of



XX

XXX
XXX
XXX
XXX
XXX

Examples 1 and 2 can be regarded as the average particle size distribution, and in 3 example clearly shows two clearly distinct size band, indicating poor melting and casting techniques or poor basic lipstick, but if examples 1,2 and 3 obtained on the same lipstick , the cause of the data presented in example 3 apparently is bad tempering.
screening methods for the determination of particle size
Dry sieve analysis is seldom used to determine the particle size, but sometimes cocoa powder with low fat and sugar melkomolotogo.
For this set of sieves with different size openings is subjected to the automatic vibration mode, then collected on each sieve material and the material is passed through a fine sieve most weighed. Thus, a representation of a particle size distribution. Dry sieve analysis is more suitable for powders which do not clog up the sieve - fatty powders often clog the sieve.
"Wet" sieve analysis
The principle of the method consists in preparing the suspension or solution of the powder in the solvent and flushing it (pure solvent) through a fine sieve. The procedure described below uses a woven mesh wire mesh 325, which is suitable for most practical purposes; virtually cocoa powder often used 200 mesh [aperture size standard UK: mesh 200 - 0,0030 inches (75 microns); Mesh 325 - 0,0018 inches (45 m)].
Now there are fine-meshed sieve, and can be measured by a particle size of up to 8 microns.
"Wet" sieve analysis (solvent)
Sieve consists of a hollow cylinder made of tinned copper with a diameter and height inches 3 2 1 / 2 inch, to which a handle in the form of a long arc. The base of the screen is covered with a flange and a standard wire mesh 325 mesh soldered along the edge of the cylinder. On the bottom side of the grid is soldered to the metal ring mesh protection when it is standing on the laboratory bench.
25 g[1] Cocoa is placed in a sieve and slowly lowered into a vessel containing petroleum ether at a temperature of 60-90 ° C. During the tests, the screen is rotated, keeping the mesh at an angle of 30 ° to the horizon. When the sieve is filled with less than a quarter, it is slightly raised so that about half of the mesh is below the surface of the petroleum ether in the vessel. When the volume in the sieve is significantly reduced, the sieve is lowered until it again becomes less than a quarter full, and allowed to drain the solution. The process continues as long as it takes, usually about 5 min, without stopping to gently rotate the screen. After this time, the remainder in the sieve will look noticeably larger than the original cocoa.
Then the sieve is transferred to another vessel containing pure petroleum ether. Cocoa, sticks to the side of the sieve, washed using the wash bottle with petroleum ether. Sieve dipped several times in ether, then raised and allowed to drain. After this screening is completed.
The sieve was dried in an oven 10 min. cocoa tails transferred to a tared dish with a small brush, weighed and calculated as a percentage number.
In the method described below as rinsing vessels can be used desiccators with an inner diameter of about 20 cm stoppered well covers.
After a number of definitions of a sieve will have a significant number of clogged holes. He washed in a large beaker with a layer of boiling sodium hydroxide solution USG about 12,5 mm thick. Sieve boiled about 2 minutes, after which the hole should be free, and it immediately rinse thoroughly with water, then with alcohol and dried in an oven.
"Wet" sieve analysis (with water)
In this method 200 mesh sieve residue was determined as described below. Full description is given in [11].
Methods. Weigh approximately 5 g of cocoa powder in 400-ml beaker up to 10 mg. Add 20 ml of distilled water and mix thoroughly with a glass rod until the complete disappearance of lumps. Then add 280 ml of hot distilled water (± 75 5 ° C) and stir vigorously 2 minutes using a mechanical stirrer such that the funnel is not formed (at about 300 rev / min). Pass the suspension through a sieve 200 mesh sieve while rotating in a horizontal plane.
Rinse the glass and the screen with hot distilled water (75 ± 5 ° C). If the slurry does not pass uniformly through a sieve, tap thereon. Attach a Buchner funnel (diameter of about 7 cm) to 500 otsosnoy-ml flask.
The glass fiber filter, pre-dried within minutes with 30 103-105 ° C, cool and weigh immediately up to 1 mg. Then moisten the filter with water and strongly press to a perforated base Buchner funnel. Rinse off with a sieve to filter and turn on the vacuum. First wash the upper part of the screen, and then lower. Wash the filter using about 15 ml of acetone and dry min at 60 103-05 ° C. Cool and weigh as soon as the filter with sediment up to 1 mg.
Calculate the percentage of sludge as a "sieve mesh 200 tails."
mikroproseivaniya method. We have already mentioned mikroproseivanie to a particle size of 8-10 microns.
In the work [13] shows that to obtain satisfactory results need adjustment vibration sieve. For information on the smaller
particles (4 microns or less) using an electron microscope, and the [17] discloses a method using a sputtering system to obtain a uniform distribution on a microscopic specimen.
sedimentation method
For information on the distribution of particle size, there are many methods based on standing. If the powder is suspended in water or other liquid, the rate at which the particles settle depends on the particle size and density of the liquid.
Suspensions on standing portion of the sample can be separated after some time and weighed. It can also be used volumetric method - measurement of sludge volume after a specified time.
Standard equipment for measurements with the defense - it Andreasen pipette. In the first edition of this book was described method of determining the degree of grinding the cocoa powder particles settling on the bottom. This method has been used for many years to determine the selected range of particle sizes in a milk chocolate. Useful aqueous precipitation technique for the study of the cocoa powder is described below. Cocoa husk comprising particle nucleus and rapidly form precipitates. In this chocolate drinks undesirable.
Test Imgoffa. Tube Imgoffa designed to monitor effluent and sediment control, but to control the precipitation of cocoa it narrowed more than to be able to receive indications to 0,05 ml (Fig. P5).
25.5
Controlled powder must be free of compacted flakes which can occur during packaging and transportation, to remove them the powder is passed through a mesh 100. Weigh 2,5 g of cocoa and move in beaker 1 l. Rinse 500-ml cylinder with hot distilled water. Then fill the cylinder to the mark 500 ml of hot distilled water. Allow to cool the water in the cylinder to 82 ° C.
As the water cools, fill the tube to the level Imgoffa 500 ml of hot distilled water (82 ° C).
Make a paste of cocoa liquid with a small amount of water at a temperature 82 ° C in a graduated cylinder, rotating glass to give water movement in a circle. Slowly add about 200 ml of water, rotating content. Add the rest of the 500 82 ml of water at ° C, without rotating the content.
Stir the mixture with an electric mixer with exactly 30, and during this time completely drain pipe Imgoffa, turning it and tapping on the tapered end for removal of residual water.
Place the tube in a rack Imgoffa and immediately transfer the cocoa suspension in a tube and let stand exactly 5 minutes.
During the deposition can be observed by placing a faint light source side of the Imgoffa tube. To make it easier to measure the amount of sludge can be used a magnifying glass.
sediment The line should be well mapped, but if it is uneven or sloping, the test is repeated.
Good cocoa suitable beverage preparation, should give the measurements with this method less 0,25 ml sediment.
Methods based on precipitation, are empirical, and some of them are very long. In addition, they say nothing about the shape of the particles.
Determination of particle size distribution by laser
This method has been used successfully to determine the size and distribution of particles in chocolate pastes and powders.
Operating principle. Low-power laser beam illuminate a cell containing a suspension of particles that can be dispersed in various organic or aqueous fluids in the cells of the small or large volume. Light scattered and make focus via a collecting optical system for a multi-element detector ring. Ring position detector is selected for each particle size distributions and measurement.
The degree of light scattering depends on the particle size - the smaller the particle, the greater the scattering angle. The detector operates continuously, the output signal is amplified, is controlled by a microprocessor.
The results of determination of particle size distribution in a table and a bar graph displayed on the display device and can be output to a printer. The principle of operation of the detector shown schematically in Fig. P6 and P7.
25.7
Fig. P6- principle of diffraction scattering. The company Malvern Instruments Ltd., Malvern, England
25.6Fig. A.7. 3600E detector. The intensity at each detector, - the sum of the intensities of all the particles of a given size. The company Malvern Instruments Ltd., Malvern, AngLeah
Coulter Counter
This method, developed in the late 1950-ies, used to determine particle size distribution. Device, known as a Coulter counter (Coulter Countei <©), first used for counting blood cells, but was later used for a wide range of materials containing particles, - powders, pastes, suspensions, and emulsions.
In this method, a slurry of the test particles is prepared in a suitable electrolyte solution and passed through a narrow opening in which there is an electrode on each side. When the particle passes through the hole, it displaces the volume of the electrolyte solution equal to its volume, for a short time changing the impedance (total electrical resistance) between the two electrodes, and modulating the passing current (similarly to the resistance change) and forming a pulse. The pulse amplitude is almost proportional to the volume of the particle. A series of pulses that occurs during the passage of a particle flow is amplified by an electronic circuit and scaled, allowing one to calculate the particles and / or determine the volume (mass) of particles or series of particles between known sizes.
For chocolate, a special electrolyte solution is needed. It is shown that the most acceptable is the 5% (w / v) solution of ammonium thiocyanate in technical or isopropyl alcohol, the chocolate particles being dispersed into a solution of fractionated (alcohol-soluble) lecithin or "Span 80" (sorbitan oleate, Honeywell Atlas). For the analysis of dark chocolate, the electrolyte solution is pre-saturated with sucrose, and for the analysis of milk chocolate, the electrolyte is pre-saturated with low-fat dry milk chocolate substances. With the help of these solutions of electrolytes and various holes, particle size distributions in chocolate, cocoa and cocoa liquor were obtained in terms of number and weight (mass or volume) in percentages up to the size of 0,5 μm. It is possible to analyze the chocolate obtained by using various processes and determine the ratios of small and large particles. It is not intended to describe the operation of different instrument models or the methods used, as they are described in detail elsewhere, but it will be interesting for the technologist to get acquainted with the particle size distributions in popular milk chocolate grades determined with the help of Coulter Counter (Fig. П8 and П9).
Determination of fat in chocolate and cocoa products
The analytical methods described in standard textbooks in detail as follows:
  • Continuous extraction with petroleum ether in a Soxhlet extractor and extractor Bolton; •
  • Werner Schmidt method that is used when the protein prevents extraction; hydrochloric heated product (salt) with an acid prior to extraction;
  • Methods Mojon and the Rose-Gottlieb (the product is treated with ammonium hydroxide and alcohol to dissolve the protein, suitable for dairy products and candy);
25.8Fig. P8. The particle size distribution, popular varieties of chocolate, the differential and total volume (mass or weight). The percentage depends on the size (m) Firma Coulter Electronics Ltd., Luton, England.
25.9Fig. The particle size distribution P9- popular varieties of chocolate, the differential size and the total number of excess relative size (microns). Company Coulter
Electronics Ltd., г. Лутон, Англия.
Gerber method (volumetric method used for the current control milk, the product is treated with sulfuric acid and then centrifuged).
Express - methods of extraction with trichlorethylene
It's simple, fast and cheap methods that can be used for the current control.
sample preparation. If possible, a sample of chocolate and cocoa must be properly homogenized and molded. Another boil
ant a homogeneous sample - finely grate a large sample and mix.
Except as described below, for the measurement is taken, the 10 Samples containing a large amount of husk, for example, whole beans and products trends, should be analyzed by Soxhlet as complete extraction is not achieved in the rapid method.
Corn cocoa, peeled from the husk - food trends: use the Soxhlet method.
Cocoa liquor. Take measurement 5 g fine shavings. If the weighing takes place in a fluid state, mix well.
Chocolate. Take 10 of Finely grate. If the weighing takes place in a fluid state, mix well.
Cocoa cake. Take 10 was milled until yet not pass through a screen mesh 30.
Cocoa powder. Take 10 of Mix sample.
Milk baby. Take 10, the Grind and sieve in the case of cocoa cake. Periodically inspect the method of Soxhlet. In some types of dairy fat crumb portion can be "locked" in the protein or sugar agglomerates.
Weighing samples. Samples 5 or 10 g, depending on the determination conditions, are weighed in a balanced metal cup. Accuracy ± 0,01 g is sufficient for weighing 10 g, but when weighing 5 g, accuracy ± 0,005 is required. The weighted sample is carefully placed in a narrow bottle with a grounded stopper of 6 ounces (-180 ml), the remainder of the sample is removed from the metal cups, tapping on them or using a camel hair brush. Then 100 ml of pure distilled trichlorethylene is added from an automatic pipette into which the solvent comes from the reservoir. Two pipettes are used, so that one can be emptied, and the other at this time could be filled. The bottle is closed with a glass stopper, its contents are shaken well and allowed to stand for at least 30 min. During this time, the contents are shaken periodically.
Filtration. The filter paper Whatman №5 (18,5 cm) is pleated, folding on the tube (sealed with a rubber stopper), get out of her "cup", and insert it into the bottle so that the filter is below the "coat hanger"
(Fig. P10). Filter paper tends to straighten and thus easily held in place. The plug is closed again.
Ten minutes is usually enough to give a sufficient amount of leachate accumulated by filtering into the "cup."
25.10
Introduction pipette. Twenty milliliters placed using a pipette of the cup-filter into a weighed wide-100-ml flask. Pre-rinse the pipette should be a small amount of filtrate.
When the current control when we study a large number of samples, rinse after the first time you can not repeat. Pipettes 20-ml shall be calibrated by automatic 100-ml pipette to get them to give exactly one-fifth volume.
Note: Always use the "safe" pipettes to avoid inhalation of trichlorethylene vapor.
Distillation. The excess solvent in the flask is removed by distillation in a special apparatus containing 8 flasks (Figure П11). This apparatus consists of a condenser with water cooling, tiles and connecting tubes. Care should be taken to ensure that distillation does not go too far, otherwise there is a risk of fat decomposition. After distillation of most of the solvent, the flask is removed, hot air is introduced inside to remove as much of the remaining traces as possible. The flask is then placed in a drying cabinet at a temperature of 90 ° C for 2 h. After cooling to room temperature, the flask is weighed again to obtain the weight of the extracted fat.
If urgently necessary to analyze the solvent by blowing hot air alone can be removed, which it takes 20-30 minutes and then cooled and weighed. It is desirable then to continue blowing for a short time to make sure the weight is constant.
Fat (%) = Weight of the extracted fat x coeff. x 100 / sample weight.
Coefficient. It takes into account the increase in the coefficient of fat extracted from the sample, calculated according to the equation
Fat (%) = x (4,988 + 0,28h) 100 / W, where x = the weight (mass) in fat 20 ml; W = weight (mass) of the sample.
25.11
For the current analysis table is usually prepared on the basis of this equation by the weight (mass) of the sample (or 5 10 g). These tables can be "coefficients" or long lists fat content corresponding to the weight (mass) of the fat obtained from 20 ml.
The temperature correction due to the expansion of the solvent. If there is a noticeable change in room temperature between measurement solvent and introducing 20 ml pipette, it is necessary to enter the temperature correction in order to compensate for the increase or decrease in volume of the solvent.
Adjusted coefficient. If the aliquot is measured at T ° C, and the temperature was initially added solvent T1 ° C, the intrinsic rate ratio = + 0,0055 (T-T1).
Removing the solvent residues. Residues after determining the fat is filtered and distilled in a bottle with anhydrous potassium carbonate.
The dried distilled solvent is filtered and stored in a bottle of yellow (dark) glasses. The residue is defined in 50 ml should not exceed 0,0010 of
Saving trichlorethylene. Trichloroethylene is subject to certain destruction when reusing and distillation. Adding 2% of industrial alcohol (ethanol) for each new batch of solvent prevents the destruction and does not affect the determination.
Refractometric methods
These methods are based on determining the refractive cocoa butter solution coefficient in nonvolatile chloronaphthalene solvent.
The procedure consists in weighing 2,5 g cocoa powder (or cocoa) in a small beaker and add 5,0 g solvent, chloronaphthalene. The mixture was heated to 70 ° C with stirring and then filtered. The refractive index of the filtrate is measured using a precision refractometer exact incubation and compared with the refractive index of the pure solvent [11].
Determination of fat by means of nuclear magnetic resonance
nuclear magnetic resonance method is a low-resolution (NMR) very successfully developed in recent years. With this method one can measure the ratio of solids and liquids in fats and to determine the fat content of chocolate products, nuts, seeds and the like. D. The method can also be used to determine the moisture.
The method is now widely used for quality control. Monitoring (Control) fat content in chocolate during production use at many large factories. Operation is simple, so it can carry out the staff who does not have training. The method requires very little sample preparation.
The initial cost of the device is high in comparison with the analytical techniques described above. However, where required frequent measurements, saving the expense of staff time and using NMR significant.
Further information can be obtained from the company Newport Instruments Ltd., Milton Keynes, England.
Determination of the cooling curve of the cocoa butter or similar fats
Meaning of "cooling curve" is explained in the chapter on cocoa butter and other fats. The method described below requires precise control of all operations.
Most large companies that produce fat, this method is completely mechanized, and uses a number of devices operating in parallel. They are used in the production control and quality control.
In a modification Shukoff-De Zaan used tube with a vacuum jacketed thermometer registering and printing. Driving Shukoff tube is shown in Fig. P12.
25.13

25.12Fig. P13. Apparatus for determining the cooling curve
Equipment for the analysis (Fig. P13)
  1. Test tube sample: tube 15 2,5 cm x cm, thin-walled, with a rim, Pyrex, relevant British Standard WB 3218: 1960, and the closed tube, through which a thermometer and stirrer. Hole with the thermometer should have a gap.
  2. Thermometer: from up to 0,5 50 ° C, with divisions 0,1 ° C Immersion 6 cm total length cm 35.
  3. Stirrer: Pyrex rod 4 mm in diameter with a loop at the lower end having a diameter such as to be approximately midway between the ball and the wall of the thermometer tube when mounted agitator. Total height of the mixer 190 10 mm ± mm. A suitable glass liner for mixers to be inserted into the tube with the sample tube.
  4. Air jacket: high chemical beaker 1 l, about 190 mm in height and 88 mm in diameter, weighted by lead shot and equipped with a cover of five layers of cardboard (felt) ~ 6 mm. Three layers of this diameter, so that they fit tightly into the glass, and two - that they lay on top of the glass. These five layers should be glued together and drilled to tightly hold the test tube in the center of the air jacket. The placement of dried silica gel in an air jacket prevents the formation of fog during measurements. The prepared air jacket is immersed in a water bath so that 2 cm remains on top, the temperature is maintained at 17 ± 0,2 ° C and gives the system an equilibrium,
  5. refraining her 30 minutes before measurement. Water bath made of glass or glass make it a window to be able to observe the contents of the tube.
analysis
Prepare fat for persecution. Melt a representative part of the sample in the oven at a temperature of 55-60 ° C and filter at this temperature through a dry filter paper. Cool the filtered fat, stirring occasionally until the temperature drops to 32-34 ° C, and then, continuously stir it by hand or mechanically until the grease reaches the consistency of the paste. Immediately transfer it to a vessel previously adjusted to a temperature of 15-22 ° and allow it to stand at this temperature for at least 24 hours before use as a primer in the determination.
Determination of the cooling curve. Transfer 15 ± 0,1 g of a representative sample of pre-filtered fat into a test tube, close it with a stopper and completely melt the contents in a separate water bath at 50 ° C. Replace the plug with a different one (with agitator and thermometer) and keep in a water bath at 50 ° C for at least 15 min, stirring occasionally. Take out the test tube with a stirrer and thermometer from the water bath, dry the tube from the outside and dry it in the air. Gently mix the sample until 40 ° C, transfer the tube into the air jacket. Clamp the thermometer so that its ball is in the center of the fat, and adjust the plug so that it can slide up the thermometer and is raised enough to insert the seed at a later stage without disturbing the position of the thermometer. If appropriate equipment is available, the stirrer can be connected at this stage to any suitable mechanical device whose speed is set according to the required mixing speed.
Periodically mix the fat until reaching 35 ° C. From this point, measure and record the temperature at intervals of 1 min and mix the fat with two neat stirring movements every 15 s so as not to destroy the surface of the fat with the stirrer loop. At 28 ° C (see Note below), quickly add 0,03-0,04g finely grated flakes that are obtained by easily scraping off a well-crystallized fat sample prepared as described in the 1 procedure. Continue to record the temperature and stir at the same speed as before, but also fix the temperature at which the first obvious signs of crystallization will appear. Finally, stop mixing as soon as the temperature increase in a minute passes its maximum, but continue to record the temperature until five identical successive results are obtained. Apply the time / temperature curve to the millimeter, setting the time along the horizontal axis, and the temperature along the vertical axis. At least two measurements must be performed on each sample.
Note. If the test oil has a solidification properties very different from the properties inherent to cocoa butter, can be a modification of the method desired. Thus, if the crystallization occurs at a temperature above 28 ° C, seed should be added to 2-3 ° C above the temperature of crystallization; moreover, the temperature at which the periodic agitation and begin reading, may require changes.
The melting point of fats
Techniques for determining the melting point of the numerous and varied. The results obtained depend on the precision of indication of the methodology used. In different countries there are recognized standard techniques - for example, a Wiley melting point USA. When you want a comparison, you should always indicate the method used.
Capillary method described below, it is widespread. Sample preparation is very important for the fat in a stable condition prior to determining the melting point.
Determination of melting point, strength and transparency (haze)
Sample preparation. Transfer 30-50 g representative fat sample to a small clean dry chemical beaker. Melt the fat by heating it in the oven to a temperature of 55-60 ° C. Filter the fat through the dry Whatman paper No. 41, keeping the temperature at the filtration of 55-60 ° C. Cool the fat, sometimes stirring, until the temperature becomes equal to 32-34 ° C, and then continuously mix until the first signs of the appearance of turbidity. When the pasty consistency is reached, quickly transfer the fat to the mold, which was previously brought to 15-22 ° C. Before measurement, soak the fat at 15-22 ° C for at least 24 hours.
Analysis.
Machinery and Accessories. Glass 400 ml. Thermometer divisions to 0,1 ° C (calibrated on a standard thermometer). The capillary tube length 5-6 cm internal diameter 1,1-1,3 mm and external - 1,4-1,7 mm, chromic acid rinsed with distilled water and then dried. Mechanical stirrer. Vata. Rubber rings.
Analysis. Roll up a little cotton wool between your thumb and index finger and insert it into the capillary. Push it inside a piece of wire, until it is at a distance of 2 cm from the end. Gently squeeze it in this position while pressing a piece of wire on the other side. Cotton tube serves to keep the fat (after he "oplyl") below the level of the water bath so that the point of the transparency can be determined on the same sample.
Push the capillary (the end with cotton wool) to fat, to get in a capillary stopper fat 1 cm long. Connect the capillary to the bulb with two small rubber rings so that the grease tube is aligned with the thermometer bulb.
In a beaker, pour pre-boiled and cooled distilled water to a depth of at least 6 cm and hold the thermometer in the center of the glass so that the lower end of the capillary was on 4 cm below the surface
water. Install a mechanical stirrer and heat the water so as to obtain a heating rate of about 0,5 ° C per minute when approaching the yield point, ie approximately 5 ° to the yield point. Determine and record:
  1. The point in which the observed softening = melting point.
  2. The point at which oil begins to rise along a capillary = yield point.
  3. The point at which the fat is transparent = transparent point (turbidity).
Softening point fats
Barnikota Method (Varnicoat) *
Principle. Methods based on the method of "ring and ball" that is used to control the bitumen is to determine the temperature at which 3-mm steel ball to penetrate a column half fat, whose temperature was raised at a rate 0,5 ° C per minute.
Tools and equipment. Glass - 2 liter, low and wide. A metal plate with a circular cut corresponding top glass, a central hole for a thermometer and a series of symmetrically drilled holes in which at its edges with hanging tubes fat. Special hole drilled shaft mechanical agitator. Tubes edges (nozzles) - Thin 5 cm in length, with an outside diameter 1 cm 3 mm (0,1 inch) steel balls (ball bearing). Standard titration thermometer. Mercury. Mechanical stirrer.
[1] Apalyst, 69, 176. - Note. author
Assembling apparatus. Place the beaker on the wire mesh on a tripod, fill with distilled water at a temperature of 20 ° C and set the thermometer and stirrer plate in place (see. Fig. P14).
25.14Fig. P14. apparatus Barnikota
Analysis. Put 0,5 ml mercury tube 5 1 cm long and cm diameter to cool the vial contents within 5 min crushed ice and water to pour molten mercury 1 ml fat leave the tube in ice water to 15 min *.
At the same time, several determinations can be made, ie, as many tubes can be placed in the lid of the device. Place the 3 mm ball from the bearing in each tube into the groove on the surface of the fat that forms when the fat cools. Place the tubes in the holes of the plate and adjust the height of the thermometer ball so that it is flush with the bars of fat in each tube. Begin the determination with a bath temperature of 20 ° C. Keep this temperature at 15 min. (Time reduced to 15 min compared to the original 30 min.) Then raise the bath temperature at a rate of 0,5 ° C per minute, stirring vigorously. Record the temperature at which the steel ball fell to half the height of the bar of fat. This is the softening point.
The hardness of fats
The method of measuring with a penetrometer. Using penetrometer (Fig. P15) used to determine the measurements of bitumen and solid hydrocarbons. It can be applied to fats and chocolate glaze. The degree of penetration of the needle or cone is measured at various temperatures and the results are discussed in conjunction with measurements of the melting point, NMR and expansion.
25.15
[1] In the initial method Barnikota tube kept in ice water 30 minutes and then placed in the refrigerator overnight. This test procedure is done too long to control the current, and it was found that it may be modified as described herein. - Note. aut.
Testing of the foam - a modified method Bikerman
Foaming test is useful for checking the foaming properties of syrups made from sugar, glucose and invert sugar syrup when used for hard caramel particularly useful if a syrup is added to boiled sweets such a blowing agent such as sodium hydrogen carbonate.
Copious foam indicates the presence of blowing agents, such as protein, saponin and mucus. They may be present in poorly refined beet sugar, and some low-grade glucose syrup. High sugar content contributes to foaming. Strong foaming properties ingredients lead to the formation of dense with small bubbles of aeration and low bulk density of an aerated product.
Low foam level may be due to the presence of traces of fat or fatty acids, usually any contamination of the equipment or container. Cane sugar, if it is poorly cleaned may contain traces {sape cane wax wax).
These "anti-foaming agents" are very harmful for the production of aerated confectionery products, they cause a complete destruction of aeration, or give a "rough" aeration with large bubbles (see. "Aerated confections").
Machinery and Accessories. Apparatus for the formation of foam (Fig. P16) includes 150-ml beaker, watch glass rods for mixing and refractometer.
25.16 Fig. P16. The device for the foam test
Disconnect tube A, empty it and rinse with hot water before the next test. In Ind. Eng. Chem. (32), p. 1594
Washing machine. Glasses, hour glass, glass rods and tubes for foaming sintered glass is washed by immersing in chromic acid solid is not less than 20 minutes and then rinsed with distilled water and allowed to drain on clean absorbent paper.
Analysis. Weigh 20-5 g of glucose or sugar (or sugar 35 g / glucose syrup) in a beaker and add 85 ml of distilled water. Add some clean glass beads, little Warm and stir to dissolve the sample. Then close the glass of a watch glass and boil the solution exactly 3 minutes. Quickly cool the solution to 20 ° C and concentration to bring 20 ± 0,5%, using a recently boiled and cooled distilled water.
Rinse the tube (A) a small amount of the solution, and re-insert the tube into its support clips.
Set the level gauge at zero by adjusting the movable scale (B) and then slowly open valve (C) controlling the vacuum until the vacuum 8 cm height gauge.
Remove the foaming tube and pour the sample to the level (E), while holding the lower outlet tube closed with your finger.
Firmly place the handset back on the rubber ring and adjust the pressure to the correct height on the pressure gauge (see 12,5 30 for glucose and see for sugar), then start the countdown. The introduction of the sample into the tube and the foaming pressure regulation should be completed within 1 minutes.
Maintain pressure 12,5 cm (or 30 cm for sugar) during the test, and fix the maximum head of foam per minute.
foam level - this foam height in centimeters after 10 min (recording readings at intervals of one minute, is used only to show the stability of the readings).
After the test, turn off valves for vacuum control, but when the bubbles in the tube for foam settle down, remove the rubber ring.
Water activity, the equilibrium relative humidity
The equilibrium relative humidity (DOM) is mentioned in several places in this book. DOM or specific vapor pressure - a moisture content at which the food product is not gaining or losing moisture, and expressed as a percentage.
"Water activity" (αω) Is now being used more frequently, but the meaning is not changed. It is measured as the proportion of the unit rather than as a percentage; eg, αω, = 0,65 - is the same as DOM 65%.
αω food products, including confectioneries, significantly affect the shelf life and absorbability. Take, for example, two on opposite ends of the product range αω- Hard Candy at αω = 0,25-0,30 and fondant cream with αω = 0,65-0,75. In temperate climates, hard candy almost always will absorb the moisture, and most likely fondant dries. Confectionery with αω= 0,75 or more vulnerable to the action of microorganisms and molds. Fig. P17 is a graph of an exemplary relation between αω and the activity of microorganisms, but the differences in the formulation of confectionery products lead to some deviations.
The moisture content of the syrup and the concentration of phase (referred to in the book) has no connection with the certain αω For example, in cereals with a moisture content 12-14% αω is about 0,65, while in oilseeds with the same αω moisture content of about 8%. Some syrups and jams with a moisture content 25-30% also have αω equal to 0,65.
25.17

As in the case of saturated salt solutions mentioned below, the vapor pressure (and hence, aw) sugar solution depends on the specific substance in the solution and the concentration.
Definition αω
In a simple practical method of determining αω (Fig. P18) using saturated solutions of various salts, which have different vapor pressures (Table. PP).
Modern hytherographs apparatus consists of cells and containing the test product.
An example of such a device is described below Protimeter.
Calculation αw /ALL
For relatively simple formulations in which only syrup phase comprises sugar, glucose syrup, invert sugar, DOM calculation can be performed by Mani and Born Equation (Money and Vorn). These investigators showed that if the concentration of dissolved substances classified 100 parts by weight of water, the equation becomes
% DOM = 100 / (1 + 0,27N),
where N - is the total number of moles of solute (mol - a unit weight of the substance is equal to its molecular weight in grams).
Subsequently, the nomogram was created [14], a series of articles [3] gave further explanation of the principles underlying the calculations. For complex formulations usually better assess DOM one of the following methods.
Definition αω c using salt solutions
This is a simple way to determine the cheapest aw confectionery.
Equipment. Used apparatus (Fig. P18) consisting of a glass jar with a lid containing a saturated solution of the salt chosen. The cap is drilled a small hole, and is passed through a thin wire terminating in a small stainless steel base. The upper end of the wire loop and provided with a small metal plate, so that the platform can be mounted close to the surface of the salt solution when the lid closes the opening in the disc. The loop at the upper end of the wire is attached to a hook

present salt



0 ° c

5 ° C

10° C

15° C

20° C 25° C

30° C 35° C

40° C 45° C

50° C

* Lithium chloride

LiSlN20

14,7

14,0

13,3

12,8

12,4

12,0

11,8

11,7

11,6

11,5

11,4

potassium acetate SN3С00К * 1.5Н20 23,0

22,9

22,7

















* Hexahydrate magnesium chloride

MgCI2-6H20

35,0

34,6

34,2

33,9

33,6

33,2

32,8

32,5

32,1

31,8

31,4

* Chromic acid (chromium trioxide)

Sg0z (N2sg207)

38,7

39,5



















Potash

К2С03-2Н20

44,3

44,0

43,7

















potassium nitrite

KNO2

50,0

49,1

48,2

















* Magnesium nitrate

Mg(N03)2-6H20

60,6

59,2

57,8

56,3

54,9

53,4

52,0

50,6

49,2

47,7

46,3

* Sodium dichromate dihydrate

Na2Cr207-2H20

60,6

59,3

57,9

56,6

55,2

53,8

52,5

51,2

49,8

48,5

47,1

Sodium bromide dihydrate

NaBr2H20

60,5

59,3

57,8

















sodium nitrite

NaN02

66,2

65,2

64,2

















ammonium Azotnokïslıy

NH4DO NOT3

77,1

74,0

71,0

68,0

64,9

61,8

58,8

55,9

53,2

50,5

47,8

* Sodium chloride

NaCl

74,9

75,1

75,2

75,3

75,5

75,8

75,6

75,5

75,4

75,1

74,7

* Ammonium sulphate (NH4)2S04

83,7

82,6

81,7

81,1

80,6

80,3

80,0

79,8

79,6

79,3

79,1

* Potassium chromate K2Cr04







86,8

86,6

86,5











* Potassium Nitrate KN03

97,6

96,6

95,5

94,4

93,2

92,0

90,7

89,3

87,9

86,5

85,0

Monoammonium phosphate, PKFA NH4H2PO4

93,7

93,2

92,6

















* Potassium Sulphate K2S04

99,1

98,4

97,9

97,5

97,2

96,9

96,6

96,4

96,2

96,0

95,8

* Данные взяты из работы Wexler, А., & Saburo, Н. (1954). Relative humidity temperature relationships of some saturated salt solutions. J. Res., National Bureau of Standards. Непосредствен но перед тестированием готовят пробу, чтобы равновесие установилось как можно быстрее, например, фадж должен быть наструган, а твердая карамель быстро размолота до крупного порошка.
pan, the bottom of the sample thus hangs freely in the pot, and the wire on which it is suspended, without regard to the holes in the cover edge.
Analysis. To conduct the test required number of bottles; saturated salt solutions are prepared in accordance with Table. PP depending on the test sample. Prepare bottles required for the test, which should be perfectly clean.
Each sample should be tested at four different atom, two above and two below the expected level, the difference between two consecutive values ​​should not exceed 5%.
Each bottle enter 50 mL brine with a known value and adjust ahyu wire, holding the foundation so that it was approximately 19 mm above the liquid level when a small disc is on the cover. Based on the watch glass is a small sample.
Allow machine to reach steady state at 18 ° C (or another temperature test) for at least one day.
Weigh the empty watch glass, wire holder and the base of each bank. This can be done by placing the jar on a "bridge" over a cup of single pan pan and pinning the top end of the wire holder to the hook on the balance beam.
Place about 1 g prepared sample on a watch glass and immediately weigh again.
Allow the machine to stand at 18 ° C (or another temperature) for two days, and then weigh the sample again, watch glass, wire holder and the base of each bank, and then record the change in weight (mass).
Weigh again a day later to stabilize until not cease to be significant changes in weight.
Calculate the percentage weight change values ​​for each atom and plot the percentage change in weight (mass) based on at. Scheduled consider al, corresponding to zero change in weight / weight. This value corresponds to the atomic sample.
If you must have made a lot of measurements, you can use the small cabinets with salt solutions and small dishes with the test confectionery. Weighing they must be provided with a lid. When using cabinets are recommended to have a small internal fan to circulate air over the solution.
Definition αω using protimetra (Rgotimeter)
This device is an electronic hygrometer (Prtimeter Ltd, Marlow, England) with a digital display. The device allows to determine the water activity, in percent relative humidity, dew point, and moisture content.
To determine the A / W (DOM) is placed in the sensor cell of special design as shown in Fig. P19 and P20.
25.19 Fig. P.19. Standard probe
25.20 Fig. P.20. Sensor device in DOM to determine cell aw
The use of DOM-cell. You can use the device to measure the DOM through sample space in the DOM-cell or other suitable container.
With liquid, viscous or lumpy materials
or
With clean granular materials for achievementsof the early results.
Protimeter Ltd., Meter House, Марлоу, Бакс, Англия
Machinery used in the production of
When you want to quickly get results, to control production processes, appliances are installed in production units.
First developed devices, which testified, then used for manual hardware configuration. Then the instruments were developed that were given the signals controllers, making the necessary changes. Now many businesses are fully computerized, provides monitoring and control of all operations and parameters, such as temperature, vapor pressure, timing parameters, recipes, chocolate tempering and viscosity.
Viscosimeters
Rheological properties of chocolate have been extensively studied in recent years. The need for economic reasons to work with chocolate that has a low content of cocoa butter, has led research of plastic viscosity and yield stress.
Simple viscometers suitable for liquid chocolate forms do not provide the information necessary when working with more viscous products.
Viscometers are described in detail in Chapter 4; below is a brief summary.
Devices such as Redwood viscometer. This flow-through devices with mesh sizes similar to Redwood viscometer №2. The method is empirical standards and prepared according to the recipes of chocolate applied to concrete factory. These devices are used only for liquid chocolate. Viscometer "Horn <1 Sir" ( "funnel Ford"), used in the paint industry, is also used for chocolate.
Viscometer to determine the viscosity of the solution by the method of the falling ball. This device is useful for determining the consistency of thick chocolate used for molding into shapes feeding through pipes and dragee. The device is less accurate than the Redwood viscometer, but more accurate results can be obtained using the incident cone with circular marks as well as through the ball (see. Also "Mobilometr").
Rotary viscometer. In the US, it was decided to use a rotational viscometer McMichael for many years. He was admitted to the National Confectioners Association of American as a simple, relatively inexpensive device, but in recent years he had been criticized for the fact that it does not provide all the necessary rheological data.
Brookfield viscometer and Haake (Naake) are increasingly being used in many countries.
Refraktometrы
Refractometers are now indispensable for the control of a candy factory. They replaced the thermometer to determine the end point of cooking syrups, jelly and jam, and when combined with the pressure of the syrup (cm. "Confectionary Technology") for determining the concentration of the syrup phase in ointments, pastes and marzipan. Below is a brief description of the various types of devices.
"Pocket" refractometer. It is relatively cheap sliding portable device with rotating prisms on one end (the mass - 241 g, length - 17 cm).
The device is available for multiple bands and can be applied to a wide range of products and syrups. For example, it is used to check the sugar content, and thus maturity apples, beets and potato. It is particularly useful for determining the change in the penetration of sugar when canning fruit.
Refractometer Abbe. Usually regarded as laboratory instruments, they are now manufactured very durable and can be used with precision in production. The refractive index is 1,300-1,740 or on the sugar scale 0-95%. A flow model is also available. In this model, the water jacket compartment, replacing the traditional folding prism, is equipped with a funnel and an exhaust flushing pipe. The funnel and the drain pipe can be replaced with fittings to connect the flow cell to a laboratory experimental setup to perform measurements of the refractive index of moving fluids. Water providing temperature maintenance comes from a fixed box with prisms, and there is no need for connecting tubes.
The immersion refractometer. This device can be used for laboratory or production work in the confectionery and food industry.
Since the accuracy of the measurements is high, it is necessary to limit the instrument range to a relatively small range of the refractive index, but by replacing one prism with another for another range, the instrument can be changed without loss of accuracy. Several ranges of prisms are produced. In absolute measurements, the result depends on the accuracy for which the instrument was calibrated, and for this reason the refractometers are mainly used for measurements by a differential method involving comparison of the refractive indices of known and unknown solutions for which the coefficient differences are small.
The body of the device consists of a rigid tube, covered with leather, so that it can be safely held. In the upper part there is an eyepiece, through which a uniformly divided scale is visible. The screw allows you to move the scale one division. The screw has ten divisions, which allows you to divide the scale into ten more parts. The scale of the critical angle appears on the scale due to the difference in the refractive index between the prism and the sample, which looks like the boundary of the division of the circular field of view into a light and dark part (the boundary of light and shade). The point at which the chiaroscene border crosses the scale gives an indication that allows us to find the refractive index of the sample using the calibration table supplied with the prism.
The lower shell has a scattering range of which is rotated to remove the border color of light and shade, and below is a prism, which is to be immersed in the test solution. Lighting, which for this device must be external, may be provided by natural light from a window or a light bulb.
To protect the prism and the sample container as the device is equipped with a metal bowl, which is partially filled with the sample so that the refractometer is useful in hand and aiming at the light source.
There are two versions of the immersion refractometer. One box has prisms with a jacket mounted in the bottom of the unit, and it is enough to sample a few drops. In another modification has attached cell through which the test liquid, and the liquid can therefore be continuously monitored.
Projection refractometer. This refractometer is widely used in the confectionery industry and works on the principle of internal reflection. This device is large and sturdy (about 75 cm length, width 15 cm 22,5 cm height) usually it does not require cooling, since the weight of the device sufficiently small for cooling the sample to ambient temperature. For special applications can be provided a cooling device.
Carrying out of measurements. The boundary of the critical angle, observed as the boundary of light and shade, crossing the scale, gives the result directly in percentage of the sugar content. Illumination is provided by one of two bulbs with the voltage of 6 V. The lamps are mounted on a rod, which is fixed on a ledge located on the side of the device. Each light bulb can be set to the lighting position and adjusted to provide (1) diffused light or (2) illumination with orange light through the filter; The second option serves to reduce the coloration of the limits of light and shade.
Power to the lamp can be supplied from an external transformer or battery. The device thus uses only a safe low voltage and in wet conditions. Scale is inside the device and is visible through a window on its upper surface.
The sugar concentration in lipstick, marzipan or candies (gum) can be determined regardless of color, optical density, the presence of grains (pips), or other particulate matter. The sample was spread on a horizontal glass surface lighting is controlled and read percentage sugar combination directly on the scale, or the need to increase the eyepiece absent. After measuring the sponge material is removed from the surface, the surface is wiped dry with a soft cloth, and it can be applied to the next sample.
Process refractometers. There are two types of refractometers - for boilers and pipelines.
Refraktometers for boilers. These refractometers are designed for direct attachment to the digester, in which cooking or evaporation is carried out. The refractive index, expressed as the percentage of solids content, usually sugar, is continuously displayed on the display, which is on the front surface of the device and which can be immediately seen. A cleaning mechanism ("janitor") is provided, which periodically removes material in contact with the surface of the measuring prism, bringing into contact with it a new layer. The cleaning device is drilled to supply water, so that in addition to cleaning, the prism surface can be washed while the boiler is running. The device uses the principle of internal reflection, so it can measure optically dense materials. The device has a built-in light source with external power supply 6 B, 0,5 A from the battery or from the network through a transformer. The refractometer is therefore an electrical safety device even in wet conditions.
Refractometers for pipelines. These refractometers are designed for direct installation in stainless steel pipes and testify continually.
There is a device, which uses the same principle as in immersion refractometer, and its reading depends on the light transmitted through the material in the tube. In another device the reflection method, and it can be used in opaque liquids.
Automatic electronic refractometers. These devices are designed for continuous recording of the refractive index and are used for special production processes. In comparison with the described devices are expensive.
Relative density and density
Determination of density or relative density (specific gravity) of syrup was the traditional method of testing for the confectioner in the past and scaling hygrometer is too well known to describe it. Now developed methods continuous monitoring and adjustment of densities, which are based on the weight of the column of fluid changes in a flexible U-shaped tube.
To control the density of whipped confections proved applicable simple cylindrical container with a bottom of the wire mesh with large cells. The vessel is filled with the whipped mass up until it begins to emerge from the wire mesh, then remove the excess mass from both ends of the knife, and the vessel is weighed. Since the mass of the dish is known in advance, you can quickly determine the density of its contents. This receptacle avoids the formation of voids which may occur in the cylinder with a solid bottom.
There are many methods for determining the physical density, which are described in the literature.
temperature measurement
Thermometers. Temperature measurement is still the method of controlling the concentration of sugar syrups and other candy syrups which do not contain the interfering ingredients such as gelatin, pectin or solids.
Accurate temperature measurement and regulation are important in tempering and cooling of chocolate. Apply the following types of thermometers.
Glass mercury thermometer. These thermometers are reliable and usually well retain their accuracy. For industrial purposes they are usually provided with protective covers in order not to break them down tank (the ball). As protection should be used an open safety grid of thick wire at the end with the ball as a thick metal housing greatly reduces the sensitivity and lead to erroneous results.
Some cookers have built-in thermometer that can be inserted into the heavy metal stirrer. Such protection can lead to much longer to retrieve evidence and significant inaccuracies in the determination of the end point.
In the United Kingdom issued the "standard" glass mercury thermometer supplied with a certificate of the National Physical Laboratory. It is useful to have such a thermometers available in the laboratory to check for other thermometers used in the pilot plant and production. They should not be used for other purposes.
Metallic mercury thermometers arrow. These mercury thermometers used in the expansion tank, submerged in the liquid, the temperature of which must be measured. The expansion is transmitted through a steel tube to a dial indicator. With careful handling, these thermometers are reliable, but the adjustment can be broken, and therefore need to constantly check.
Thermometers working on the expansion of the air. These thermometers scale moves by expansion of the air in the tank. They can be very unreliable, and should not be used where accuracy is required constant.
Thermocouples and resistance thermometers. The use of these devices has increased significantly, their particular value lies in the high sensitivity due to the small size of the sensor compared to other thermometers balls described above. They are also very easy to work with recorders.
There are many portable thermometers with thermocouples, which are very sensitive and reliable for careful handling. Unfortunately, they are often mistreated, and they are no longer accurate. These thermometers should be checked regularly for glass mercury thermometer.
Telemetry techniques. To measure the temperature in the tunnels, cooling devices, and so on. D. Available radio telemetry devices. These devices emit signals which are transmitted to the receiver, and they are not required for wiring or piping connections. Very useful for temperature control on the moving conveyor in closed spaces.
On the issue of specialized thermometers several companies, and they can provide all the information needed for any particular process.
Thermometers for infrared part of the spectrum. These instruments accurately measure temperature without contact. They are especially useful for temperature measurement of highly viscous substances, which often clog the thermometric sensors. Telescopic system with lighting Indoor directional light lamps provides temperature measurement is always at the same point.
Monitoring thermometers. Despite assurances from the manufacturer of thermometers, thermometers frequent errors. All thermometers are received at the factory, they must be checked. This may be used, oil bath and stirred temperature control (thermostat). The bath should be large enough to scan several thermometers. The thermostat periodically set at different temperatures so that the thermometer can be checked at a certain temperature range.
Check thermometers "to install" is also very important, so the heads of production units should carry out regular checks. When errors are detected thermometers should be replaced immediately. Very bad when the plant operator must introduce a correction to the measured temperature or bulb attached to a tag indicating a correction to be making.
To test should be used "certified" thermometers mentioned above.
Эlektronnыe vlagomerы
Electronic measuring instruments used in many industries to determine the moisture content of powders or granular products such as flour and grain.
In the confectionery industry one of the most important applications - is to check the moisture content of the starch in the casting apparatus for casting and after dryers.
The principle of operation of most devices is based on the capacitance, and the material to be tested is in a cell of standard dimensions. To obtain reliable sustainable results it is important that the packing density was constant and the majority of instrumentation provided with the means to achieve the constancy of packing density.
However, the required periodic inspections gravimetric (weight) method, and, if this is done, it is possible to quickly obtain correct results for one type of material. To measure each type of product or raw devices should be calibrated.
There are other electronic methods for the determination of moisture in the course of production.
moisture meters
It is often necessary to obtain data on the relative humidity in the factory premises, such as warehouses, premises, where we are working with the starch or crystallization. The easiest reliable device - a sling hygrometer used in combination with the correct psychrometric tables.
Psychrometer Mason (in the form of dry and wet bulb) is notorious for its unreliability, if not provided the appropriate means to ensure air flow around the ball thermometers. These psychrometers, hung on the wall in the still air, completely useless.
Where necessary the continuous recording, best results are obtained by recording hair hygrometer, but it requires regular inspection and adjustment. Recording psychrometer dry and wet bulb as psychrometer Mason is reliable only with good air movement. "Wet bulb" is composed of a bimetallic spiral with a damp cloth from covering. Hair-hygrometer is much more sensitive.
The device, which is considered a standard reference hygrometer - this diet graduate psychrometer (Assmann psychrometer). It consists of a sensing wet and dry thermometer in the cylinder are provided with a small fan which supplies ambient air to the beads at the standard speed.
Another type of device - a paper or bayonet hygrometer. It can be sandwiched between layers of paper or cardboard container, and then stored at a relative humidity the equilibrium moisture content can be determined, and hence the moisture content of cardboard.
Literature
  1. Apparatus for determinations of Isotherms for water vapour sorption in foods. Department of Food Science, Agriculture University, Wageningen, Holland.
  2. British Standard BS 3406: Part 5. 1983. British Standard Methods for Particle Size Distribution. Part 5. Recommendations for Electrical Sensing Zone Method (the Coulter Principle), 33 p.
  3. Cakebread, S. H. 1970. Mafg. Confect. 50(11), 36; 50(12) 42; 51(1) 25.
  4. Chemical analysis and its application to candy technology. Conf. Prod. 161. London.
  5. Coulter, W. H. 1956. Proc. Nat. Elect. Conf. 12,1034 (Coulter Counter® is a registered trademark of Coulter Electronics Inc.)
  6. Coulter Counter® Industrial Bibliography 1986, (1521 references) Coulter Electronics Ltd., Luton, England.
  7. Instruments for the Food Industry, British Food Research Association, LeathPOBead, Surrey, Eng­land. (Series of leaflets on special equipment.)
  8. Jacobson, A. Chocolate - Use of N.M.R. in the Chocolate Industry. Cloetta, Sweden.
  9. Lockwood, H. C. 1958. A new method for assessing chocolate grinding. Chem. &Ind., 1506-1507, Nov. 15.
  10. Meursing, E. H. Cocoa Butter, Quality and Analysis. Cacaofabriek de Zaan, Holland.
  11. Meursing, E. H. 1976. Cocoa Powders for Industrial Processing. Cacaofabriek de Zaan, Holland.
  12. Money, R. W., and Born, R. 1951.]. Sci. Fd. & Agric. 2,180.
  13. Niediek, E. A. 1978. New equipment for determination of particle size. Chocolate, Confectionery, Bakery.
  14. Norrish, R. S. 1964. Conf. Prod. 30, 769.
  15. Reade, M G. 1971. Fat content by refractometer. Rev. Int. Choc. 26,334-342.
  16. Refractometers, electronic moisture meters. (From a series of 17 papers on Candy Analysis, B. W. Minifie.) Confectionery Production (1970 et seq) London.
  17. Sutjiadi, I., and Niediek, E. A. 1974. Preparation methods for control of fineness (in German). Gordian, 284-291.
  18. Van den Berg, C. 1983. Description of Water Activity of Foods for Engineering Purposes. Inter­national Congress, Dublin, Ireland.
  19. Department of Food Science, Agriculture University, Wageningen, Holland.
  20. Wiggins, P. H., Ince, A. D., and Walker, E., Rapid determination of Fat in Chocolate and Related Products Using Low Resolution N.M.R. Cadbury Schweppes, Boumville, Birmingham, England.
Manufacturers
  • Baird and Tatlock, Romford, England (miscellaneous equipment)
  • Bellingham and Stanley, Ltd., London (рефрактометры)
  • Raytek Inc., Mountain View, Calif, (thermometers for the infrared part of the spectrum)

[1] For the current control can be used 10 g of cocoa. Note: Fine cocoa powder during this test is less than 2% «tails." This method can be tested and cocoa mass, cocoa liquor and small will be less than 1% «tails." - Note. aut.
Last Update Saturday, November 07 2015 19: 54
Vladimir Zanizdra

Founder Baker-Group.net site. More than 25-years of experience in the confectionery industry. More than 20-five years of management experience. Experience in the organization and design of the production from scratch. Site: baker-group.net/contacts.html El. mail This e-mail address is protected from spam bots. You need JavaScript enabled to view.

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