Given that milk can be contaminated with microorganisms to a significant extent, it is necessary to

Contents Introduction Microbiological examination of milk Sampling and preparation of dilution Determination of the total number of microorganisms in 1 ml or 1 g Microbiological preservation of food examination of fermented milk products Microbiological examination of cheese pathogenic microorganisms in milk and dairy products Coliform bacteria Escherichia coli, Salmonella Proteus Staphylococcus, Clostridium aerobic mesophilic spore-forming bacterium Bacillus subtilis type - determine the total number of 1 ml of milk thermophilic aerobic spore-forming bacterium Bacillus-type (Geobacillus) stearothermophilus - confirm preservation of food the presence of lipolytic bacteria in milk - the isolation, identification and determination of the total number of 1 ml or 1 g of Literature
The accuracy of food is essential for the health of consumers. He must therefore perform their strict quality control. Foods may be defective due to faulty materials, errors in production (production technology, pollution inorganic or organic compounds, microbial contamination) or long-standing prior use (reproduction of microorganisms). Increase trade and imports of food products, extending the time of transport of food to the final consumer, and thus increases the possibility of development of undesirable microorganisms.
Under the milk, in the broader sense of the word, means the liquid white, specific flavor, which is secreted by the mammary gland at some time after parturition female mammals and used for feeding their young. Different types of milk contains the same components, but their relationship may be very different (Djordjevic, 1982).
The composition of milk depends on many factors (species, breed, period of lactation, nutrition, etc.). The average chemical composition of the milk of domestic cattle is as follows (www.tehnologijahrane.com): Water - 87.5% protein (casein, whey proteins) - 3.13%, carbohydrates (lactose) - 4.84%, fat 3, 76% mineral matter (micro and macro elements) - 0.8%, gases (CO2, O2, N2), the other ingredients (vitamins, enzymes, other nitrogen components).
Due to its composition of milk is a very suitable substrate for the growth of microorganisms, among which may be pathogenic to CEVEK. After milking milk contains about 1000 micro-organisms in 1 ml. Eventually their numbers increased, and due to their metabolism changed the sensory, physical and chemical properties of milk. As milk contaminants commonly referred preservation of food micrococci (Micrococcus, Staphylococcus), fecal enterococci preservation of food (Enterococcus facalis), preservation of food enterococci mastitis (Enterococcus. agalictiae E. dysgalactiae), asporogene spores gram-positive rod-shaped bacteria (Microbacterium, Corynebacterium, Arthobacter, Kurthia, Bacillus) and asporogene gramnegativne bacteria (Pseudomonas, Acinetobacter, Flavobacterium, Enterobacter, Klebsiella, Escherichia, Serratia, Alcaligenes).
Given that many of the microorganisms present in milk harmful to humans, Regulations on microbiological food traffic, as prescribed mandatory microbiological analysis of milk ("Official Gazette preservation of food of the FRY", no. 26, 1993): Determination of the total number of bacteria in 1 ml or 1 g, Isolation and identification of species of the genus Salmonella, Isolation and identification of coagulase-positive staphylococci, Isolation and identification of species of the genus Proteus, Isolation and identification of E. coli, Isolation and identification of bacteria sulforedukujućih.
Microbiological control included: Raw milk, sterilized milk, pasteurized milk, while there is a dairy Pasteurized milk sold to consumers at the time, milk powder, condensed milk, sweetened, condensed skimmed milk sweetened, condensed unsweetened milk, condensed skim milk, unsweetened.
Method preservation of food of sampling depends on the types of containers, which varies in the purchase, production and sale to consumers. Samples are taken under aseptic conditions, and must be representative for the whole amount of milk. If the milk is in tanks or buckets, samples are taken with sterile supplies and packed in sterile, dry container and should take at least 200 ml. Samples must be tested within 24 hours. If the milk is in the original package is taken one package or at least 500 ml. If the package is lightweight, samples are taken of the total weight of 100 g
Given that milk can be contaminated with microorganisms to a significant extent, it is necessary to make appropriate dilutions. Primary dilution is 1:10. . Determining the total number of microorganisms in 1 ml or 1 g
This method preservation of food involves direct counting of cells in milk smear under the microscope. Sterile micropipette applied 0.01 ml of the sample plate with marked square area of 1 cm2. The preparation preservation of food is naked color staining (methylene blue) and viewed under a microscope (Immersion Lens). The disadvantage of this method is counting the live and dead cells, which creates preservation of food an error in the assessment of the degree of contamination of the sample.
In this procedure, preservation of food 1 ml of the appropriate dilution was pipetted into a sterile Petri plate and poured with 15 ml of melted and cooled to 45 oS substrate for the total number of bacteria. In order to precise