The problems of microbiological character rancidity.

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The problems of microbiological character rancidity. Chocolate and confectionery are not as susceptible to damage by the action of micro-organisms such as fish or meat, and even in cases where the place described in this section undesirable processes, spoiled products does not have any pathogenic influence, except, of course, that someone it may begin to stir at the sight of a chocolate bar, which has lost its normal color, or taste of rancid confectionery.

However previously used ingredients can be habitat of microorganisms, whereby the feed contains toxins.

Production and packaging of chocolate and confectionery products is carried out in conditions which can not be considered aseptic, but still edible products due to the low moisture content or the content of a large number of soluble solids.

The main reasons are corruption:

The composition of products fall enzymes contained in the feed, in addition, they can be introduced already in the company if hygiene requirements are not complied with; most enzymes are inactive, if the content of soluble solids than 75% or if the moisture content of the product is very low (as in the case of chocolate).

There rancidity caused by exposure to the air; catalysts of this process are the effects of light, heat and certain metals. Such rancidity caused by oxidation reaction; rancid peanut and other vegetable oils have nepryatno taste.

"Soap" rancidity is caused by the fat-decomposing enzymes; in this case the hydrolysis reaction, and such rancidity may occur later and not immediately possible to guess that the emerging flavors associated with the effect of ferments.

It molds itself becomes noticeable in the later stages of growth, when the hyphae covered product; eating it would be disgusted by him comes repulsive odor.

If the mold has suffered only a small portion of the feed, for example, the products lying in the bag where it turned wet spot, or in the case where the nuts or moldy cocoa beans inside mold can grow and remain undetected by the entire mass of the food product.

Mould in the food product leaves spores, fat-decomposing enzymes and toxins. As a typical example of the latter can result in aflatoxin which may be present in peanuts.

If production does not comply with the requirements of hygiene, the equipment and piping may be contaminated PlessisStrongly and enzymes, which ultimately lead to the above types of damage to the product.

In the past, the fermentation fillings in chocolate sets, packed in boxes, happened quite often, and the entire set was lost due to a tainted candy, chocolate shell which burst under the pressure of carbon dioxide, making the whole box flowed sticky syrup with beer smell.

Fortunately, now the manufacturers are good properties of microorganisms that cause fermentation, and carefully calculated for its share recipes of various sugars, so that fermentation was a rare phenomenon, and when it occurs, it is usually the cause of non-compliance with prescription or technological requirements.

Fermentation confectionery is most often caused by osmophilic yeasts (Zygosaccharomyces, Torulopsis). These microorganisms are able to grow in the sugar syrup high in soluble solids. They can cause damage to honey, golden syrup, raw sugar, fruit juice concentrates, as well as dried fruit and fruit preserves. In the past, the fermentation confectionery explained bacterial activity, since these microorganisms could be isolated from fermented products, while osmophilic yeast did not develop in a medium consisting of the ingredients used. There are two ways to avoid fermentation products: 1) eliminate as far as possible, the use of raw materials, which is the source of osmophilic yeast and 2) provide such a high concentration of syrup phase, to suppress the activity of the yeast. Sporadic cases fermentation may be associated with fruits, nuts, cocoa, flour of some cereal species, and other natural products which are the primary source of this yeast, and in addition, provide for their protein environment, an additional source of supply of yeast. Desirably any confectionery, which contain these ingredients, heat 82 ° C or higher and maintained at this temperature by 15 20 to minutes; Only sterilization is sufficiently effective when carried out in a humid environment; for example, when the composition prior to incorporation into confection ingredient heated in syrup.

Osmophilic yeasts may be found in industrial piping and valves, where the raw confectionery residues are stationary. This is especially true where the production is carried out intermittently. These organisms are developing with ever greater energy, therefore it is essential to comply with occupational health requirements, and regularly sterilized with live steam or using disinfectant detergents all piping, valves, mixing and shredding machines. For preventedIt is usually sufficient to ensure that the concentration of the syrup phase is more than 75% by including a portion of liquid glucose (corn syrup) or invert sugar, 2,5-3 times the percentage of moisture content in the confectionery, i.e., the confectionery composition Enters approximately 25-33% of glucose or solids of inverted sugar. However, isolated cases were recorded when osmophilic yeast caused fermentation of syrup, the concentration of which exceeded 75%. The reason for this was most often the use of one of the above ingredients without first sterilizing it, or microbiological contamination of the equipment.

To delay the fermentation process, the pH can also reduce, or included in preservatives approved for use.

Jam or fruit paste, having a pH of up to 3,0 3,5, resistant to most of the fermenting organisms. The content of soluble solids may be relatively low to 72%; a pH level also prevents the development of mold. Some organic acids such as acetic, lactic and sorbic also inhibit fermentation, but is not permit use of sorbic acid as an additive. Acetic acid and lactic acid allowed to be used, because these substances are found in natural products, but to achieve a good taste products should be included in very small amounts; especially acetic acid.

It is enough to be an effective action of sorbic acid, when its share is up from the 0,1 0,2%, and acetic - by up to 0,05 0, 1%.

As acceptable preservatives fruit pulp, fruit preserves and dried fruit, as well as some other products, can be used sulfur dioxide and benzoic acid; the exact amount of preservatives allowed for use, should be found in the regulations in force in each country.

Therefore, we can conclude that it is necessary to prevent fermentation:

1.   Always maintain a level of soluble solids above 75 %.

2. Check suspicious materials and carry out its sterilization before or during the manufacture of confectionery products.

3.  Strictly comply with occupational health and monitor the presence of fermenting microorganisms feed on the remains of the equipment.

The use of preservatives, optionally, except in special cases.

Rancidity. Food products in general often suffer from rancidity caused by oxidation, that is occurring due to the air, but the flavor is spoiled confectionery usually due to rancidity caused by the hydrolysis reaction. Most often, this process is associated with enzymatic (fat-splitting lyayuschim) effect ingredients containing lauric fat used in recipes confectionery frequently.

Rancidity caused by oxidation reaction. Under the influence of air oxidation of fats and oils containing unsaturated fatty acids and esters; rancidity occurs due to the formation of aldehydes and ketonesHaving a characteristic odor and taste.

Rancid oils and fats can be developed and increasingly due to auto-oxidation. Sdeduet understand that a rancid means all kinds of unwanted flavors - often talk about salistom, fish, or a metallic taste. Sometimes mistakenly assume that the taste is caused by extraneous impurities, when in fact only the initial herd takes placeI am rancid. The analysis showed that the natural taste of foods that we eat is determined by a combination of aldehydes and ketones, very close in composition to that found in rancid foods.

Some people may not notice a rancid taste, while others feel it very thinly; This is especially true for the rancidity caused by the oxidation reaction. Oxidation of fats is a complex chemical process, and for most fats there is a period of induction, when rancid taste is almost imperceptible, and after a while the rancidity caused by the oxidation reaction begins to be felt stronger and stronger. This phenomenon is associated with the formation of peroxides, so to determine the rancidity of fat, including at its initial stage, the peroxide value is determined. How fat or oil is unsaturated can be determined based on its iodine number - the higher the iodine number, the easier the fat can rancid. To determine the duration of the induction period through the oil, a constant flow of air or oxygen is passed at a constant temperature, and the graph shows how the weight of the oil changes over time. The sharply accelerated increase in weight coincides with the end of the induction period. In the "Peanut" section, another method is mentioned, using the so-called oxygen bomb. Many fats and oils contain natural antioxidantslaces, in particular tocopherol and lecithin, which can prevent oxidation and rancidity or delay the development of the process; products can be added to natural and synthetic antioxidants. In Examples BHT (butylated hydroxytoluene) and "Sesamol" (Sesamol) (obtained from sesame oil); "Antioxidants" for more on this, see. Section.

It is interesting to note that some compounds act as synergistic agents with respect to the antioxidants, - it can be said of citric and phosphoric acids, different amino acids and other substances contained in the products of plant and animal origin.

Readers wishing to learn more about such chemical processes that may apply to a large literature on oils and fats.

Technology of food production increasingly have to deal with the prevention of rancidity.

In the first place it is important to fats and fat-containing purchased materials were of high enough quality.

Then you need to organize production so that a good raw material is not spoiled during processing. Oxidation of fat is enhanced by the action of heat, light, and when in the presence of some metals.

Heating of fat. Good fat often spoils due to improper melting. Nowadays, fats are often supplied in unpacked form, in tanks, and they can be used immediately, and there is no risk of spoiling them with excessive overheating; it is very good. If you still have to melt solid pieces of fat, then stainless steel vessels heated with a water jacket should be used - boilers with steam heating should be used undesirable, because operators, wanting to ensure a constant availability of fat ready for use, not only set the temperature too high, but And withstand liquid fat for a long period at this temperature. Besidesoh fat by pouring a thin layer of fat boiler contacted with air being heated to a surface temperature of the boiler, which, in essence, is the temperature of the heating steam in the jacket (taking into account the pressure being applied). This thin layer of fat spoils very quickly.

gratings are often used, heated by steam or hot water. Such a grating is composed of tubes in which circulates hot water or steam; pieces of fat are placed on the grid. The fat is melted in places where it touched pieces tubes and drains into the substituted container below the grid. This system is preferable to the boiler steam heating, but should monitor any temperature reaches fat.

Metals. promote fat oxidation of iron, and to an even greater degree of copper; It is undesirable as the presence of metals and others. The equipment from aluminum alloys or tinned copper is considerably inferior to stainless steel equipment; a common drawback, as the use of stainless steel between the boilers and pipes of brass or bronze valves.

To the melted fat preferred storage temperature will be lower 60 ° C; In no case can not be exceeded temperature 71 ° C, and if the fat to be stored for a longer period, the maximum allowable temperature is 49 FROM.

Lighting. Fat deteriorates much faster if a bright light falls on it; if pieces of confectionery fat will be in the rays of sunlight, then layer on the surface of rancid quickly. If the blocks of fat or fat shredded delivered to production premises in the carts, they should be cleaned regularly, so there was not the slightest amount of fat; these trucks should never be left under the windows, where they may be exposed to bright light.

Rancidity due to hydrolysis reaction. There are different ways of splitting fats into components - fatty acids and glycerine; this process is called hydrolysis. The small degree of hydrolysis occurs when the wet product is heated in oil; most foods hydrolysis occurs under the action of enzymes. Lipase decomposes the fat into glycerol and fatty acids, but some kinds of lipases cause not only the degradation of fat, but also other compounds and water-soluble fatty esters. It is necessary to remember those who study the problem of rancidity.

Rancidity caused by the hydrolysis reaction, the so-called "soapy rancidity", can be considered the most unpleasant defect confectionery products, which include fat. The reason for it is the presence of fat-decomposing enzymes, which are found in foods such as coconut, dairy products, egg albumin and cocoa. Lipolytic activity may also begin during the preparation or storage of the product under the action of the mold. Mold can occur in some places and a damp quietly spread throughout the product.

Splitting fat lipolytic enzymes does not always lead to the emergence of a soap taste, but in the case of lauric-type fats presence there is very strong "soapy" rancidity. Lauric (dodecanoic acid) (Ci] H23COOH) refers to the number of saturated fatty acids; its name comes from the names of plants of the family, Lauracaeae, In nekotorыh reptives which among natural glycerides more than 90% of lauric acid. The most common fats containing lauric glycerides are coconut and palm kernel oil (in which their content is to 40 50%), milk fat, and (to the content of 2 6 %). Lauric acid is not contained in the cocoa butter, illipe butter, palm oil and peanut. Only the least amount of free lauric acid is sufficient that the product purchased soapy taste.

It is noticed that the pastry with coconut most prone to rancidity. Several years ago, studies on this issue have been conductedAnd valuable information was obtained, which since then is based on individual cases rancidity caused by the hydrolysis reaction. It has been proven that with coconut pastry or similar fat-containing ingredients, which were added to the lipase prepared from castor seed for deactivation of the enzyme to be heated to a temperature of up to 88 93 FROM. To ensure that such sterilization, in practice, it is most convenient to carry out the sterilization of coconut turned to his inclusion in the confectionery product, and was created equipment to be included in the continuous phase of the technology. A thin layer of coconut, located on the conveyor belt with a thin layer, pour steaming - while also destroyed Salmonella and other micro-organisms that may be in dried coconut. Was shownThat cause rancidity caused cleavage coconut fat is present Micrococcus candidus, М. luteus, М. flavus, Achromabacter lipolyticum и Bacillus subtilis. Since then, in the regions, cultivating coconut, significant progress to avoid the presence in the finished raw coconut fat-decomposing enzymes was achieved.

For the preparation of milk candies, fudge and other pasty confectionery products, an emulsion of milk fat is prepared, made from dry or condensed milk with the addition of sugar and fat. It turned out that the rancidity of such confectionery products is due to the fact that the milk emulsion, stored for a while before its use, has time to quickly rancid. The rancidity caused by the hydrolysis reaction also occurs in fat-containing confectionery, in which egg albumin is added in the form of whipped frappe. The presence of lipase in egg albumin can be explained by the fact that during its preparation egg white was contaminated with yolk, and yolk fat was removed from the formulation with the help of stipsin.

According to some authoritative experts in the syrup mixture with albumin lipolytic organisms can inactivated during the pasteurization via 20 minutes at 71 ° C and the tests carried out by the methods described below, indicate that the most likely possible lipolytic action. Nevertheless shelf life test of fat-containing confectionery, which was added to the frappe pasteurized albumin showed that this treatment may okazatsya insufficient and in some cases "soap"Rancidity still there. The temperatures required to inactivate the lipase, to a large extent depend on the properties of the substrate. Protective properties in this respect have a high concentration of sugar syrups, fats and the absence of water; to inactivate conventional confectionery enough temperature by up to 88 93 ° C, but it was found that dry powders these organisms can survive at temperatures above 104 FROM.

Some types of cocoa (for example, press expeller residue) can cause serious problems with rancidity, and the use of this ingredient in confectionery products with low moisture sterilization syrup is often impossible. In such cases, for the suppression of enzyme activity may be diluted in fat cocoa slurry to the state and the resulting mass is heated for min at 5 107 ° C.

For these purposes, use a heat-resistant stable fat or frying oil. In recent years there have been many studies on deterioration products with low moisture content. It was found that the activity of the microbes and enzymes is largely determined by the activity of water, rather than water content.

We investigated the effect of water activity on enzymatic reactions and it has been found that the most common enzymes (amylase, peroxidase and phenol oxidase) with a water activity less 0,85 are inactive. In contrast, the lipase remained active at rates below the 0,3 and even if the water activity constituting 0, 1, and under such conditions it has demonstrated extraordinary resistance to thermal breakdown. At a low water activity of the reaction with lipase occur very slowly.

It is noted that at a water activity below 0,90 little bacterial growthprobable; molds and yeasts are inhibited for the index of up to 0,88 0,80, except for certain types of osmophilic yeast, which retain their activity at a lower water activity (up to 0,6). By reducing the water activity thermal destruction becomes more difficult.

Identification lipolytic activity. Identify the presence of lipase is quite difficult especially at very low activity; moreover, it should be noted that bacterial enzymes can remain still for a long time after the bacteria themselves are killed. a variety of methods proposed to be used for these purposes, and despite the factThat some of them have been successfully applied in relation to specific materials and specific recipes, they can be very unreliable.

A variety of chemical tests are used, for example, an indoxyl acetate test. At pH 7,2, indoxyl acetate is hydrolyzed by esterase of various origins, and the resulting indoxyl under the influence of atmospheric oxygen quickly acquires a blue-violet color (indigo). In another test, agar with glyceryl tribotyrate is used; This medium can be used to determine the number of lipolytic organisms by sowing or counting colonies under a microscope. This method was modified to improve sensitivity. To carry out the test, "Sigma" is taken 1 g sample that is kept for hours at 24 37 ° C, the sample is mixed as an emulsion with olive oil, buffered to pH 7,0, and the content of free acid determined by titrimetric analysis with the alkaline solution titrant.

The most reliable, even if it takes a long time is the organoleptic method, so using it should always check the results of chemical tests.

Described the following method: a homogeneous mixture of a control sample, palm oil and sugar syrup kept for 3 months. at 36 ° C. During the entire period of the organoleptic tests carried out on a regular basis.

Mould. Mould not only leads to the appearance in food microorganisms, enzymes and toxins, but also the causes staining and unpleasant taste.

If the water activity is reduced in the confection so that inhibits mold growth at normal temperatures, it does not mean that in tropical conditions will experience the same stable.

If you have to put on a tropical country markets confectionery products in sealed packaging, it is necessary to determine the activity of the water at high temperatures; Sometimes, when there are sudden changes in temperatures in the upper part of the packing-free local condensation may occur, can lead to mold growth.

If confectionery, packed in tight wrapper (Sweet, Chocolate with soft filling) are stored at warm temperatures, mold can cause thinning of small areas on the surface of products. The source of infection are often mold spores (as well as bacteria) present in the starch, which is molded in confections. This problem can be avoided if the process regularly starch, which products are molded in an autoclave and an oven, but because of the low vlagosoderzhaniya sterility can not be achieved; however it was the conditions in which generally produces molding confectionery products, rarely aseptic.

It is undesirable to be exported to countries with a tropical climate are very soft and contain a lot of moisture pastries.

Graining, sugarcraft. Crystallization, which in the confectionery business called "graining", is a defect filling chocolates, candy and soft candy, toffee, fruit preserves and jams. Chocolate graining does not happen, and the presence in it is sometimes rough and hard crystals is due to insufficient tempering, and crystals are formed on the surface of the chocolate in diabetes graying. Products, damaged grain size, acquires an unpleasant texture, like a grain of sand; graining sometimes causes other types of damage.

Graining can be caused by:

1.  Incorrectly selected quantitative ratio of various Sugars in the confectionery recipe. Typically, sucrose is crystallized and the crystals grow slowly, they may reach a large size and resemble sand. Sometimes dextrose crystals are formed, which can form clusters of larger growths. Of the products, which include milk, for example, from Fudge sometimes crystallize lactose. Formed crystals are very slow, their texture is very tough.

2.  Storage in unacceptable conditions. Dissolved sugars in toffee, candy and soft caramel are in a supersaturated solution state, and crystallization slows down due to the extremely high viscosity of the sugar solution. If the surface absorbs moisture or the temperature rises, the viscosity decreases and crystallization begins. Granulation also occurs when, during storage, the liquid phase in the confectionery dries out and the formation of coarse sucrose crystals begins.

3.  Incomplete soaking of fruit, candied fruits or ginger in the process of making preserves, resulting in uneven distribution of fruit inside the fruit. After some time, coarse crystals, like grains of sand, appear inside the fruit preserves; they consist of sucrose or dextrose.

4.   Cleavage of protective colloidal crystallization retardants such as gelatin or egg albumin.

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