The blended formulation apple-sugar mixture is directed as needed for cooking.
The main task of cooking marmalade mass is gom to remove excess water and create the most favorable for gelation ratios of pectin, sugar, acid.
In the process of cooking, the pectin substances are converted into a soluble state of fruit and berry puree, including the part of them that remained undissolved after incomplete hydrolysis of protopectin during fruit blending. However, the cooking conditions must be designed so as to prevent excessive cleavage of pectin substances until the polygalacturonic chain breaks and decay products are lost, which have lost the ability to gel. In this regard, the most negative effect is prolonged cooking and a high boiling point of the mass.
When cooking fruit and sugar mixture is a rapid and complete dissolution of sugar.
Important in the process of cooking is the inversion of sucrose, which develops under the action of heating and organic acids of fruits, residual sulfurous acid, present in the puree as a preservative.
The presence of known amounts of invert sugar and other reducing substances in the marmalade mass is necessary. The reducing sugars play the role of an “anti-crystallizer” for sucrose.
The mechanism of action of reducing sugars in the marmalade mass as an anti-crystallizer, or a factor that inhibits the crystallization of sucrose, can be represented as follows. The sucrose content introduced into the formulation is about 65% by weight, which exceeds the saturation concentration of the aqueous solution of sucrose at room temperature. Substitution of a part of sucrose (granulated sugar) with products of its inversion during cooking results in a decrease in the concentration of sucrose in the fruit-sugar mixture and in eliminating the state of saturation (and supersaturation) of the solution with sucrose.
It is also known that the combined presence of several sucrose in an aqueous solution increases the total amount of sugars; held in solution, which also reduces the risk of crystallization of the solution, in this case, the release of sucrose into the solid phase. Meanwhile, an excess of invert sugar at low concentrations of sucrose in the composition of fruit and sugar mass can also lead to saturation (and supersaturation) of the solution due to glucose, which has a weaker solubility compared to sucrose and fructose. In this case, it becomes possible to sugar the mass due to crystallization of glucose.
The data of many studies and the available experience show that in the presence of 14-16% of reducing substances in the marmalade mass, a state of equilibrium is achieved that practically eliminates the crystallization of any sugar from this medium.
It should also be noted that the accumulation of invert sugar in the process of cooking above the specified norm leads to an increase in the hygroscopicity of the marmalade and reflects negatively on its persistence in storage.
When using applesauce with a normal acid content, the amount of invert sugar obtained during the cooking process does not exceed the required norm.
Increased accumulation of invert sugar contributes mainly to the cooking time. In view of this, it is necessary to achieve faster cooking, especially when working with mashed potatoes that have high acidity or are highly sulfitated.
The VNII study indicated an effective means for controlling the inversion of sucrose when cooking marmalade mass in vacuum machines - regulating the degree of vacuum in the cooking space. Therefore, when cooking in vacuum machines, it is recommended to change the vacuum depending on the desired accumulation of invert sugar. It is quite obvious that if necessary, the inversion amplification should reduce the vacuum and vice versa.
To prevent excessive accumulation of invert sugar during the cooking process of marmalade mass (as well as in the subsequent process of drying marmalade), the introduction of alkaline or buffer salts into the prescription mixture has recently been practiced. However, the latter, when working with slightly acidic purees, even with small dosages of these salts, lead to the need to introduce invert sugar into the marmalade mass from the outside in the form of an invert syrup.
In the process of cooking marmalade mass from mashed potatoes, preserved with sulfurous acid, SO removal is also achieved.2 of the boiled down mass. Desulphurisation is more successful when cooking mass in vacuum machines, especially if the latter are equipped with agitators.
On the other hand, during the cooking process, the volatilization of the aromatic substances of the fruit and berry puree also occurs. To reduce the loss of valuable volatile components of the raw materials, it is also necessary to avoid delaying the cooking.
When cooking the fruit-sugar mass, its readiness is determined by the state of moisture of the mass.
The moisture of the mass to be boiled is controlled using a refractometer, which makes it possible to determine it within 1 — 2 minutes. up to 0,5%.
To control the degree of boiling mass is used as the thermometer showing the signaling or mass boiling point. cooking temperature control is precise enough boiling mass when operating in open or boilers in a vacuum apparatus, if the latter is maintained at the end of cooking the same vacuum.
For boiling marmalade mass in large enterprises are continuously operating serpentine cooking apparatus; with a small size of production use spherical or universal vacuum cooking apparatus.
The continuous marmalade pulping process was developed and carried out at the Moscow confectionary factory "Udarnitsa" on the basis of research conducted by the VNIII and the factory team. For this purpose, the coil column of the caramel vacuum apparatus of the Yaroslavsky plant system (without a vacuum chamber) is adapted. An apple-sugar mixture with an initial moisture content of 43 — 45% is sent to the collection before the cooking plant. The feed coil of the brewing column is powered by a plunger pump, with which the prescription mixture can be adjusted.
Boiling the mixture in the coil is carried out under atmospheric pressure to a final moisture content of 31--33%. The end of cooking can be controlled by a thermometer at the mass outlet. The duration of the mass in the coil is 1-2 minutes. the temperature of the mass exiting the coil is 106-108 °.
Cooked weight comes from the coil in the receiving cone, which acts as a steam trap, to release it from the vapor bubbles.
The productivity of one cooking column with a heating surface 7,5 м2 is about 6 g per shift for marmalade mass or 5,3 t for ready-made marmalade.
High productivity of continuous cooking of marmalade mass and short-term heating of the recipe mixture in the best way resolve the issue of preserving the gel-forming ability of pectin and regulating sucrose inversion. Continuous cooking allows deeper boiling of the mass without harming pectin, as well as the natural taste and color of applesauce, and creates the necessary conditions for (full automation of process control and regulation.
In small enterprises, they use a universal cooking vacuum apparatus for quick cooking of marmalade mass. Load (in the upper digester) apple-sugar mixture in an amount calculated for the mass yield of 25 - 40 kg.
The masses are boiled under pressure of heating steam 4 — 5 ati to the final moisture content 31 — 33% for 6 — 8 min.
Transfer the mass to the lower vacuum cup, in which the mass is additionally condensed to a moisture content of 29 — 31% for 1 — 2 min. The content of reducing substances in the welded mass 14 — 16%, the total duration of cooking is 7 — 10 min.
When using a spherical vacuum apparatus set the vacuum from 400 to 600 mm in gauge. Heating steam pressure not lower than 4 ati.
Sucked from the collection mixer apple-sugar mixture in an amount to provide data at the end of cooking conditions for 12 min.
Processing (cutting) marmalade mass
At the end of cooking, the marmalade mass is sent to a collection-mixer mounted above the filling mechanism. Add dyes, flavoring substances (supplies or essences) at dosages established by the laboratory and mix thoroughly. Acid is added to the mixed mass, depending on the need (acidification.
The amount of added acid should be adjusted according to the directions on the basis of laboratory data pH marmalade mixture and the pH of applesauce.
In production, it is often practiced to introduce some amount of sugar by the end or after the end of cooking. This order of work gives the production worker an additional means to control the moment of gelation. At the same time, the part of sugar necessary for the formation of jelly is turned off from the load on the cooking of the marmalade mass. This eliminates the premature loss of pectin gel from the marmalade mass (clotting). Such a danger arises at the moment when, in the marmalade mass, as a result of excessive condensation, the ratios of sugar, acid and pectin necessary for gelation are created.
Premature jelly formation is highly undesirable; it results in the fact that the jelly formed immediately after cooking with further manipulations (cutting the mass, mixing and pouring it) is destroyed and it is no longer possible to restore it as a jelly without re-cooking.
Due to the fact that the introduction of a part of the required amount of sugar is postponed to the end of cooking, a slight decrease in the temperature of the marmalade mass during cooking is also achieved, since the boiling point of the mass depends on the sugar concentration.
To a large extent, these difficulties are eliminated during the transition to continuous cooking of marmalade mass, as in the conditions of short-term heating and rapid circulation of the prescription mixture, pectin hydrolysis and sucrose inversion are minimized.
After tinting and flavoring with a temperature of about 80-85 ° and a humidity of 30-31%, the marmalade mass is poured into molds using a casting mechanism located above the forming conveyor carrying marmalade molds. To avoid stiffening of the mass, it is necessary to isolate the pipelines along its route to the hopper of the casting head. The latter is equipped with water heating, which makes it possible to temper the mass in the range of 78–80 °, that is, slightly higher than the point of gelation of the mixture (~ 70 °).
Forms for marmalade are made of stainless steel, porcelain or ceramics.
In the absence of mechanical casting, the mass is poured manually into molds mounted on a conveyor or on tables. For this purpose, special stainless steel funnels with one or more drain holes are used. When working with periodically operating cooking appliances, it is necessary to calculate the work in such a way that the mass pouring from each boiler lasts no more than 10 minutes, or the walls of the collector into which the mass is poured must be insulated in order to avoid its jamming.
The beginning of gelation of apple pectin under these conditions, i.e., with a content of 1% pectin and about 65% sugar, occurs at a temperature of 70 °. If the hot mass is poured into molds before it has cooled to the indicated temperature, then it is poured freely and easily. Otherwise, the mass partially stiffens, loses its ability to flow freely from the funnel and is poorly formed.
Process jam Sadki
Located in the forms of marmalade mass cools rapidly, mainly as a result of contact with the cold walls of the mold cells. In these circumstances, the temperature decreases marmalade for 4-6 minutes. to 60-70 °, t. e. up to the point of gelling pectin.
The process of gelling is in production practice the name of the "cages" of marmalade. The cooling of marmalade is accompanied by an increase in the degree of supersaturation of the marmalade mass with sugar. Due to the strong dehydrating effect of excess sugar, the jelly framework is formed quickly. The latter gradually grows stronger and stronger. After some time, marmalade jelly is easily removed from the mold, amenable to cutting with a knife, etc.
Actually, the cage process usually ends within 10 minutes. Thus, the residence time of marmalade in the forms amounts to about 15 minutes. The duration of the cage is important for production, since the turnover of forms and the size of the production area required for this section depend on it.
With a weak pectin, improper cooking, insufficient acidity or incorrect recipe, the marmalade batch can be delayed in forms to 30 — 40 minutes. and more.
The duration of the charge depends mainly on the acidity, or rather on the pH of the mass. The higher the concentration of hydrogen ions, the faster the cage passes.
The stronger the marmalade mass is boiled, the sooner the cage process develops (provided that in the process of boiling
pectin was not particularly injured). At the same time, the acceleration of the charge is affected by the high degree of supersaturation of the solution (marmalade mass) with sugar.
The speed of the set depends on the quality of pectin. Normally gel-forming apple pectin gives a gradual growth at a temperature not higher than 70 °. Between the end of cooking and the beginning of the set, there is enough time for draining the mass, transferring it and pouring it into forms.
Ventilation of the open surface of marmalade in the molds, which promotes free evaporation of water from the jelly and better cooling of the mass, is of great importance for the process of caramelizing. Ambient temperature also plays a role. The thermal conductivity of the mold material is also important.
According to the research data of VKNII, the following parameters of the air passed into the zone of the forming conveyor are recommended: speed ~ 5 m / sec, temperature 20 °, relative humidity 60-70%.
The role of alkali and buffer salts
In order to regulate the speed of gelatinization of pectin in the practice of producing artificial (jelly) marmalade, jelly bodies of candies and jelly on pectin basis, buffer salts were widely used abroad. The most typical of them are: cremotartar, (sour tartrate C4Н506K), diammonium phosphate (NH4) 2НР04, monosodium citrate NaC6Н7О7 and others. The addition of these salts leads to a slowdown in pectin production. The introduction of buffer salts into the jelly pectin-sugar mass makes it possible to push the casting time apart, since the mass retains its liquid state even as it cools.
In the USSR, at the suggestion of Hildebrandt et al., The use of salts for the production of natural fruit and berry marmalade is regulated. In practice, currently using NaC lactic sodium3Н5О3And Na2NR04 with a dosage from 0,1 to 0,35% by weight of the mixture of prescription, and the dosage of salt is changed depending on the total (titrated) acidity of applesauce .
The choice of these alkaline sodium salts is due to their availability. These salts allow free mechanical pumping of marmalade mass without special precautions; there is no need to strictly limit the time for casting the mass, which is especially important in the absence of thermal insulation of pipelines for the mass and its manual casting.
The addition of salts to the prescription apple-sugar mixture eliminates the need for constant mixing to prevent the loss of ion-bound gel before cooking the mixture. It plays a positive role in decreasing the drying time of marmalade, since it allows deeper boiling of marmalade mass to a moisture content of 31–32% instead of 36–38%.
The main disadvantages of making salts in natural fruit and berry marmalade are as follows.
The addition of disodium phosphate, sodium lactate, and other salts with an alkaline nature in an amount from 0,1 to 0,35% by weight of the prescription mixture shifts the pH of the latter to the alkaline side, while the pH increases by 0,3-0,8. This leads to a decrease in the physiological sensation of natural acidity, which characterizes the natural taste of fruits and berries. As a result, the need arises for the mandatory addition of acid to the marmalade mass. However, it is difficult to achieve the restoration of the initial acidity of the apple-sugar mixture, since in acidified or buffered medium, artificial acidification gives too little pH shift.
The addition of sodium salts of alkaline nature, causes peptization of pectin and therefore affects negatively the texture of marmalade. Experience shows that this, in particular, deteriorates the ability of marmalade to select it from the forms.
The introduction of alkali salts of sodium in excess of 0,1% by weight of the formula mixture delays the inversion of sucrose when cooking marmalade mass and drying marmalade to such an extent that causes for the most part the need to invert syrup into marmalade.
The slowdown of the process of setting marmalade, caused by the addition of salts, reduces the productivity of the casting equipment.
Vyborka Marmalade form
At the end of the marmalade shed, it is ready for sampling and sieve layouts. A special mechanism performs the operation of sampling marmalade and lays it on perforated aluminum sieves.
Employees of the Moscow confectionary factory "Udarnitsa" created a special unit that allows in the conditions of large-scale production to mechanize casting, loading, selection and sizing of marmalade on the sieve (Fig. 13).
The hot marmalade mass, ready for pouring, is fed by gravity or by means of a pump into the hopper of the filling head of the 1 machine.
When entering the 8 piston filler, the mass is extruded into rectangular stainless steel cells installed on the 2 conveyor.
The filled molding conveyor 2, passing through the box 3, is cooled, meeting in its way a stream of conditioned air.
Fig. 13. Driving unit for casting, cages, and the sample layout jam.
Around the end drum, the molding conveyor passes through the lower 4 duct, where the moisture from the surface of the marmalade additionally evaporates.
Under the 9 hot plates, metal forms heat up on their backs; at the same time between the marmalade and the surface of the cell forms a thin layer of syrup, weakening the adhesion between them.
Next, the 2 molding conveyor comes in contact with the 5 conveyor belt, whose web, pressed by the 10 rubber roller to the molding conveyor, is pressed into the mold cells and removes marmalade from them, since the latter adheres to the rubber layer of the web.
The canvas of the conveyor belt, bending around the end roller And at an acute angle, shifts the marmalade that separates from it onto the sieves 12 moving on the chain conveyor 6.
Sieve with marmalade removed from the chain conveyor and transported on trucks to the dryer.
The washing box 7 is used for periodical washing of the molds with water jets directed upwards. The four-speed speed variator allows you to adjust the number of casting cycles and the speed of the transporters interacting with each other. The performance of the machine varies depending on the time of setting marmalade.
In the absence of a marmalade sampling mechanism, it is selected from its forms at the end of the set-up with the help of forks (single, double, structured).
With the same forks, marmalade is laid on the sieve with the pattern up, in even rows.
The described mechanism for selecting marmalade from forms has not fully proved itself in practice. Therefore, other sampling methods are currently being developed.