Milk defects are determined by the illness of feed, microflora, incorrect processing technology, violation of the conditions and storage terms and other reasons.
Vices of taste - the most common type of defects. As a result of the vital activity of lactic acid bacteria or intestinal sticks, milk acquires an acidic taste.
Furious taste is formed in milk when it long storage In low temperatures under the action of lipase enzymes. Rocky taste also appears in the milk of the last days of lactation.
The bitter taste is due to the activities of rotten pepton bacteria in milk, and can also be caused by the presence of wormwood.
Unpleasant specific tastes can appear from the presence of nettle, garlic, onions, turnips, radish, field mustard, and others in the diet.
Salted taste in milk appears in some diseases of the udder.
Metal flavor acquires milk as a result of the interaction of lactic acid with a metal metal.
Salici taste occurs in milk when storing it in light as a result of oxidation of milk fat oxygen.
Smoky flavor and smell are possible in sterilized milk and packets, if paper facing is allowed when gluing transverse seams of the package.
Color defects appear under the influence of pigment bacteria with the formation of redness, scoring and yellowing of milk. Sometimes the yellowing of the color of milk is associated with falling into milk when issuing blood due to the painful state of the animal.
The vices of smell are most often due to specific smells of feed or unsanitary conditions of premises in which animals contain animals. The smell vices include cylinders, rotten, cheese, garlic, etc.
Consistency defects are formed as a result of the vital activity of some microorganisms. Milk acquires thick consistency with the participation of lactic acid bacteria, mucous membrane or dying - under the action of mucus-forming bacteria. As a result of the development of the bacteria of the intestinal stick, milk is subjected to fermentation and foam is formed. When bacteria that distinguishes the renewed enzyme, milk is coagulated during heating even at low acidity.
When milk freezing, its quality is noticeably reduced: the colloidal state is disturbed, as a result of which the milk is separated; At the walls of the packaging, the leaning ice is formed, fat floats to the surface, and the protein concentrates in the central and lower parts. When peeling in milk, flakes and lumps are formed. The taste becomes watery and sweetish.
Milk, obtained within seven days after the hotel, is called a colostrum. It does not withstand pasteurization, has increased acidity and elevated albumin, globulin and salts. It is not used for recycling.
The old milk is milk obtained within 7-10 days before the cessation of milking.
It has a salty voiced taste consequence of changes in the mineral composition and the presence of lipase. Butter From such milk is unstable when stored, the cheese is poor quality. Ancient milk acceptance is not subject to.
6 . Requirements for the purchase of milk
Technical requirements:
Milk cow raw.
Milk must be obtained from healthy animals in farms that are safe for infectious diseases in accordance with the rules of veterinary legislation, and in quality to comply with the requirements of this Standard (GOST 13264-88).
Milk after the milk must be filtered and cooled in the farm no later than 2h. After the boil.
The milk is raw with a reception at the enterprises of the dairy industry should have a temperature not higher than + 10 ° C, and with a surcharge in the farm - not higher than + 6 ° C.
Milk should be natural, white or weak creamy color, without precipitation and flakes. Milk freezing is not allowed.
Milk should not contain inhibiting and neutralizing substances. The content in the milk of heavy metals, arsenic, Aflotoxin M) and residual amounts of pesticides should not exceed the maximum permissible level.
Milk should be a density of at least 1027kg / m3.
Raw milk is divided into three varieties - the highest, first and second in accordance with the requirements specified in Table No. 4.
Table # 4 Cheese Milk Cow
Milk intended for the production of products baby food and sterilized products must meet the requirements of a higher or first grade, but with the content of somatic cells, not more than 500 thousand / cm3 and the heat-resistance of being not lower than the 2nd group.
Milk intended for the production of renewed cheeses must meet the requirements of a higher or first grade, but contain somatic cells of no more than 500 thousand / cm3, and on the renewed - fermentation sample comply with the requirements of not lower than the 2nd class. The content of the dispute of mesophilic anaerobic lactate-saving bacteria in the current milk must be no more than 10 in cm3.
Milk designed to produce baby food products, sterilized products and renewed cheeses, are taken with an appropriate allowance for purchase price.
Milk that meets the requirements of the highest, first or second variety, the temperature above + 10 ° C is taken as, "uncooled" with a corresponding discount with a purchasing price.
Mass fraction of fat and protein in milk must comply with basic standards.
Milk density 1026 thousand / cm3, acidity 15 ° C and from 19 to 21 ° C is allowed to be taken on the basis of the control sample by the first or second variety, if it is organoleptic indicators, purity, bacterial dissemination and the content of somatic cells complies with the requirements of the standard. The validity of the analysis of the test sample should not exceed 1 month.
Milk Cow, subjected to farm thermal processing. Milk, obtained from cows in dysfunctional facilities for infectious diseases and allowed for use in food by veterinary legislation should be filed, subjected to a thermal processing industry immediately after the milking and cooled to a temperature not higher than 10 ° C. It is not allowed to mix such milk with raw milk derived from patients with animals.
Milk, subjected to thermal processing, is not as varieties and in quality it must comply with the requirements of this standard.
Acceptance of milk.
Organoleptic indicators, temperature, density, purity, acidity, mass fraction of fat and pasteurization efficiency determines in the above milk party.
The mass fraction of the protein, and the content of somatic cells determines at least once in the decade. The results of the tests apply to milk taken between and the following analysis.
Bacterial dissemination and inhibitors are simultaneously determined at the same time at the same time once in a decade. Additionally, bacterial dissemination and inhibiting substances can be determined at the petition of the economy, but at least more than once in the decade.
When the inhibitory substances are detected, the demand of milk adopted by the economy to the analysis refers to not a variety, but the heat treatment subjected to the farm, pumped out, pay for a reduced price if the remaining rates of milk meets the requirements. The acceptance of the next game of milk received from the farm is delayed before obtaining the results of the analysis for the presence of inhibitory substances and a bacterial seeding during confirmation in the presence of inhibiting substances milk for acceptance is not subject to acceptance.
Thermal resistance is determined in each batch of milk designed to produce baby food and sterilized products.
The rejuve-fermentation sample and content of mesophilic anaerobic lactate lactate bacteria are determined at least once in a decade in milk intended for the production of renewed cheeses.
Neutralizing substances determines in milk if they are suspected.
Moloto raw inappropriate requirements of the second grade, as well as milk from disadvantaged farms for infectious diseases that fulfill the requirements established by the standard for not varietal milk, acceptance for food chains
Milk defects are determined by the illness of feed, microflora, improper processing technologies, violation of the conditions and terms of storage and a number of other reasons. Accordingly, the specialists classify them on defects of feed, bacterial and physicochemical origin. The most common type of defects of the bacterial and fodder nature of the defects of taste. So, milk acquires acidic taste as a result of the activities of lactic acid bacteria or intestinal sticks.
A ruling taste is formed in milk with long-term storage under conditions of low temperatures under the action of lipase enzymes, as well as in an old milk. The bitter taste is due to the activities of rotary peptonic bacteria, and can also be caused by the presence of wormwood in the feed. Unpleasant tastes can appear from the presence of garlic animals, onions, turnips, radish, rustling rustles, and others. Salted taste in milk appears in some diseases of the udder. Metal flavor acquires milk as a result of the interaction of lactic acid with a metal metal. Salted taste occurs in milk when storing it into the light as a result of oxidation of milk fat oxygen. Smoky flavor and smell are possible in sterilized milk and packets, if paper facing is allowed when gluing transverse seams of the package. Color defects appear under the influence of pigment bacteria with the formation of redness, scoring and yellowing milk.
Sometimes the yellowing of the color of milk is associated with the fall into milk of blood due to the painful state of the cow when milking. The smell defects are most often due to specific smells of feed or unsanitary conditions of the premises. The smell defects include rotten, cheese, garlic and others. Consistency defects are formed as a result of the vital activity of some microorganisms. Milk acquires a thick consistency with the participation of lactic acid bacteria, mucous membrane or dynamic effect by the effect of mucus-forming bacteria. As a result of the development of the bacteria of the intestinal stick, milk is subjected to fermentation and foam is formed. When bacteria that distinguishes the renewed enzyme, milk is coagulated during heating even at low acidity.
Physico-chemical nature defects include a colostrum, ancient, ice cream milk, milk with a fatal taste. Milk, obtained from cows in the last 5 days before launching (the old manner) and in the first 7 days after the calving (colostrum), is not subject to food target. It does not withstand pasteurization, has increased acidity and elevated content of albumin, globulin and salty. The old-fashioned milk has a salty and burned taste due to changes in the mineral composition and the presence of lipase. Creamy oil from such milk is unstable when stored, cheese is poor quality. Ancient milk acceptance is not subject to.
When freezing the quality of milk is noticeably reduced: its colloidal state is disturbed (milk is stratified), on the walls of the container, the fat is formed, fat pops up on the surface, and in the central and lower parts - protein concentrates. When peeling in milk, flakes and lumps are formed. The taste becomes watery and sweetish.
I. M. Burykina, Ph.D.,
GNU Northwest Milk and Lugopastrate Research Institute, Vologda
Milk is a product that should be immaculately clean and guarantee health to the consumer. In violation of veterinary and sanitary and hygienic rules for obtaining, primary processing and storage, quality deteriorates and deviations of milk properties caused by vices. The normative indicators of milk are determined by the requirements of GOST R 52054-03 "Milk natural cow raw materials. Technical conditions" Since the deviations of physico-chemical and microbiological indicators are not called malfunctions of milk-raw materials, it is obvious that the vices of its organoleptic properties are considered. According to this classification, there are vices of taste, colors, odor, consistency (Fig. 1).
The appearance of the above values \u200b\u200bis most often associated with the development of microorganisms falling into milk from ambient, as well as with the composition and quality of used feed. If we consider the entire spectrum of the causes of the occurrence of vices, then several groups can be distinguished, each of which has its own sources. The proposed classification is presented in Fig. 2.
The vices caused by the presence in the diet of the excess of certain types of feed, give the milk specific organoleptic properties - the fodder taste and smell, soap, bitter taste, blue shade of color. These malfunction of milk-raw materials can provoke an excess in the stern of plants such as green rye and barley, rape, radish, garlic, fresh nettle, Source, Field Horsetail, Rope, Feed Cabbage, etc.
Use in the diet of excess feed yeast, bards, mezgi, cake, thieves can lead to fermentation (foaming) of milk.
Vices of taste and smell are manifested in milk when using poor-quality feed (fallen, moldy) - silos, hay, feed cabbage, beets, fish flour, drinking water with algae, etc.
The most numerous group forms the causes associated with the activities of microorganisms. Their development leads to the appearance of vices and colors, and odor, and taste, and consistency. Flow color is most often associated with the development of pathogenic bacteria, but the change in the color of milk is very rarely observed. The formation of a bitter or salted taste, as well as a water-based consistency of milk, contributes to the disease of the cow endometritis, mastitis, tuberculosis, catarrhal inflammation.
In non-compliance with sanitary and hygienic conditions, milk can be abundantly infected with microbes. Milk microorganisms from the external environment and the activation of the development of native milk microflora lead to the formation of numerous vices.
As a result of the activities of lactic acid bacteria, milk acquires an acidic taste. If yeast develops together with lactic acid bacteria, foaming appears. A bitter taste in milk can cause some types of yeast, in this case it is accompanied by the emergence of the smell of fermentation. The development of psychrotrophic microorganisms also leads to the appearance of bitter taste. The burnt taste gives the development of fluorescent chopsticks and other types of microorganisms with lipolytic activity. Soap taste caused by the development of rotten sticks.
Sometimes there is a smell in the cheese milk, similar to the smell of potatoes. Psychotrophic bacteria are also causative agents. Fish, fruit and metallic taste also often occurs as a result of vital activity of various bacteria.
IN separate group Vices should be distinguished, the cause of which is a violation of technological standards for the preparation and primary processing of milk. It should be noted that the basis of some of the occurrence of some bacteriological.
Conditions of retraining of the milking process affect the appearance of silo, chill smell in milk. The right organization of milking, timely diagnosis of diseases of the udder, observance of lactation deadlines make it possible to avoid vices related to the milk of mastic, old-fashioned milk, colostrum.
Violation of technological regimes of storage of injury and transportation is due to changes component parts Firu milk (lipolysis) and proteins (proteolysis). Most often, this is due to late cooling, intense machining when pumping and stirring milk. In this case, the structure of lipid and protein components is disturbed, and this worsens the organoleptic and technological properties of milk. Milk fueling leads to a change in both fat and protein fractions of milk.
When adding or entering the milk, the flavors are more often manifested later when producing dairy products.
The quality of milk-raw materials directly affects the quality of products produced from it. The technological service of the milk processing enterprise is almost impossible to eliminate the defects of the organoleptic properties of the incoming milk. The only way to liberate milk from foreign odors is deodorization (deodorization), but for many milk processing enterprises, it is practically not available.
Effective measures can bring coordinated actions of the quality of the raw materials of the dairy plant and the zootechnical service of the agricultural enterprise, including educational explanatory work on obtaining high quality milk.
Quality indicators equal milk products
When determining the quality of products, the state of consumer and transport packaging, the state of marking, organoleptic, physico-chemical and microbiological indicators are taken into account.
Organoleptic indicators in fermented milk products are their consistency and appearance, color, taste and smell. According to consistency and appearance of prokobvash, yogurt and kefir should have an undissressed bunch, moderately dense, without gas formation. For products made by the reservoir, a grid content of homogeneous consistency may be disturbed. A minor selection of serum is allowed on the surface of the procubosity (up to 3% of the product volume). In kefir, this deviation should not exceed 2%. In kefir, gas formation is allowed by a normal microflora in the form of separate eyes, and in Kumyas - significant gas formation.
The consistency of sour cream should be homogeneous, moderately thick. Type of product glossy. It is not sufficiently thick, slightly viscous consistency and the presence of separate air bubbles.
Equality cheese should have a gentle, homogeneous consistency. In low-fat cheese there may be a slight selection of serum and crumbling consistency.
The color of the prostrup and kefir - white, ryuzhenki - light cream, yogurt - white or a bit cream (fruit-berry - color of syrup), sour cream - white with a creamy tint, fermented cheese - white, slightly yellowish, with a creamy tint. In fermented milk products, the color should be homogeneous throughout the mass; The taste and smell - clean, without extraneous tastes and smells, in Ryazhka and Varbenice he will have a pronounced taste of pasteurization.
In products with the addition of sugar, fruit-berry syrup, etc. There must be a pronounced taste and smell of additives. The taste and smell of acidophile-yeast milk, kefira and kums are fermented milk, refreshing, slightly sharp, with a slight taste of yeast.
Of physico-chemical indicators In fermented milk products, the temperature, mass fraction of fat, vitamin C (in vitaminized products), dry substances, moisture (in cheese and raw materials), acidity, phosphatase are determined. The temperature of the dairy products during the release from the enterprise should not exceed 8 ° C. The mass fraction of fat, vitamin C, dry substances and sucrose should not be less than the data specified on the marking or in the regulatory and technical documentation. Mass fraction of moisture is: in the cheese - from 65% (grained cheese) to 80% (low-fat cottage cheese), in raw products, depending on the recipe - from 25 to 75%.
Defects of fermented milk products
The reason for the occurrence of defects of fermented milk products is poor quality raw materials (milk, additives), violation of cooking technology, non-compliance with the conditions and timing of storage.
Inexpressed (fresh) taste is predetermined by reduced acidity and weak aroma. The defect occurs when using a poorly-quality break (weak acid) or at a very low well temperature.
Bread and unclean taste arises due to the pollution of milk or the frivolous microflora. The pronounced acetate and oily-eyed taste appears when developing the corresponding microflora. Too sour taste may occur with very long-lasting milk rolling, late cooling and when the storage period is exceeded. Feed flavor moves from milk. Gorkyness is a consequence of fat oxidation. Metal flavor occurs when used for storage products (sour cream, cheese) poorly tinted containers (flask, bidons, tanks).
Sour cream and milk cheeses can mold, as a result of which there is an unpleasant taste and smell. The westness of the production (cheeses, sour cream) may occur with long-term storage of it in rooms with elevated temperature and relative air humidity.
The most common defect for the consistency of fermented milk products is serum isolation. This defect arises due to the use of poor-quality milk and cream, overweight, disturbance of the storage of products, sharp jogging during its transportation and implementation. Intelligence in fermented drinks and sour cream gas-forming bacteria is the cause of product swelling. In acidophile-yeast milk, acidophiline, kefir, Kumyse is allowed (without increasing the tutor of the intestinal stick).
Pulling consistency of beverages occurs if there is a significant amount of mucous membranes in the solder of fermented milk bacteria. Liquid consistency of sour cream may occur in case of insufficient maturation, and the mercury - as a result of poor mixing in the process of rolling and cooling.
The separating consistency of fermented fermentation cheeses is due to a switching or insufficient decoction, and dry (crumbling) - increased beaming temperature or too much duration of this process.
Defects of fermented fermentation products are increased content in their composition of intestinal sticks, the presence of pathogenic microflora. The cause of such defects is a low processing temperature of milk or cream, an insufficient quadruse varnish. The duration of the bower increases, which leads to the activation of foreign microflora, in particular the pathogenic. Defects of fermented milk products should also be considered pollution of containers, disruption of sealing, poor labeling, inconsistency with the requirements of regulatory and technical documentation relative to the temperature, acidity, fat content, moisture (for cheeses and raw materials), sucrose (in products with sugar adding), dry substances, Vitamin C, etc.
Defects may be characterized by freshly dried milk, as well as occur during storage as a result of the life of microorganisms. At the same time, the composition and organoleptic properties of milk are significantly changed.
Defects of taste and smell.
Sour taste (Increased acidity) is due to the activities of lactic acid bacteria in violating the modes and terms of the storage of milk.
Furious taste is manifested in hydrolysis of fat under the action of milk lipase or lipase of microorganisms at low storage temperatures. The defect is often detected when ancient milk containing a significant amount of lipase.
Bitter taste arises when the proteins are decayed with the formation of peptons having a bitter taste. The decomposition of the protein is due to the action of peptonized bacteria, which fall and develop in milk with violations of the sanitary and hygienic mode of its production, storage and transportation at temperatures below 10 ° C; More often occurs in restored milk.
Bitter taste also happens if there are significant amounts of bitter plants in the feed.
Oxidized taste is also called oleist, fat, metallic or sunny. It is due to the accumulation of fat oxidation products in milk: oxyc acid, aldehydes, ketones. The reasons for the appearance of this defect are the effect of sunlight, ultra-violet rays, air, high temperature, as well as the storage of milk in an unclear iron and copper dishes, because metals, especially copper, contribute to the oxidation of dairy fat.
Salon flavor appears due to the change in the saline composition of milk in some animal diseases.
Feed lifts and smells occur during the transition from feed in milk characteristic taste and essential oils.
For this reason, various tastes and smells may appear in milk: a hollow, garlic-onion, solid, scene, cabbage, etc.
Foreneous lifts and smells appear as a result of absorbing milk volatile compounds (hydrocarbons, esters, ketones, etc.). Therefore, the joint storage and transportation of milk with sharply smelling products is not allowed.
Milk having these defects of taste and odor is not allowed to implement as drinking milk intended for direct consumption; He is directed to processing.
Color defects. Milk can buy red, pinkish, blue, blue or yellow shades. Change natural color Milk is associated with the development of pigment-forming bacteria, some yeast and blood from damaged udder, eating herbs with pigments, with some diseases (with mastitis and tuberculosis - bluish, with emptyra - yellow), mixing with colosum (yellow), milk storage in zinc tableware (bluish).
Consistency defects. Sometimes milk acquires mucous membrane (hard), cotton or frothy consistency. This is due to the activities of various microorganisms in violation of the regimes and the timing of the storage of milk.
