o Primary flora of raw milk: Contamination at the level of the udder and the tip of the nipple. Amphoteric property or isoelectric point in milk:<\/strong><\/p>\n If acid or alkali is added, the pH does not change.<\/p>\n Types of milk proteins:<\/strong> What are the most comprehensive compounds in milk? o Primary flora of raw milk: Contamination at the level of the udder and the tip of the nipple. o Contamination with cold-loving microorganisms: Through bedding, soil, water, plants. o Contamination with coliforms: Soil, bedding. o Contamination with spore-forming microorganisms: Bedding. Main factors affecting milk contamination: Milking […]<\/p>\n","protected":false},"author":1,"featured_media":1494,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"categories":[28],"tags":[],"class_list":["post-1493","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-28"],"acf":[],"yoast_head":"\n
\no Contamination with cold-loving microorganisms: Through bedding, soil, water, plants.
\no Contamination with coliforms: Soil, bedding.
\no Contamination with spore-forming microorganisms: Bedding.
\nMain factors affecting milk contamination:<\/strong>
\nMilking equipment<\/strong>
\nUdder tissue<\/strong>
\nEnvironment<\/strong>
\nSecondary factors influencing milk contamination:<\/strong>
\nTemperature and time
\nRoutine test for milk contamination:
\nTotal bacterial count
\nPremium milk contains 30,000 microorganisms per cc.
\nMastitis factors:<\/strong>
\nStreptococcus uberis, Galactiae, Disgalactiae
\nNipple tissue is mostly contaminated with Staphylococcus and Streptococcus.
\nMycobacterium lactinum is 100% resistant to pasteurization.
\nThe most important bacillus in contamination is Bacillus licheniformis.
\nBacillus is transferred through silage and bedding.
\nCold-loving bacteria produce lipolytic and proteolytic enzymes during growth, which are heat-resistant.
\nComponents in milk:<\/strong>
\nWater: 78.5%
\nDry matter: 13%
\nFat: 3.9%
\nProtein: 3.4%
\nLactose: 4.8%
\nDue to the presence of a two-layer membrane around fat globules, the enzyme lipase cannot break them down.
\nInternal: Phospholipid, Glycoprotein
\nExternal: Membrane protein
\nMelting points of important milk fats:<\/strong>
\nMyristic acid (14-carbon): 54\u00b0C
\nPalmitic acid (16-carbon): 56\u00b0C
\nStearic acid (18-carbon): 69\u00b0C
\nOleic acid (18-carbon with double bond): 14\u00b0C
\nUsing green fodder + cotton seed cake: Increased oleic acid and softening of butter.
\nUsing woody fodder and sesame cake: Increased myristic, palmitic, stearic acids and hardening of butter.
\nThe part of the amino acid that contains amine and carboxyl groups is hydrophilic.<\/p>\n
\nCaseins: 80%
\nSerum: 19%
\nMembrane: 5%
\nTo separate casein proteins, we use acidification or proteolytic enzymes.
\nSerum proteins are heat-sensitive and denature quickly.
\nIn protein structure, calcium, magnesium, and phosphoric acid are added to micelles.
\nPhosphoric acid gives proteins special consistency.
\nAt the freezing temperature of milk (0.55\u00b0C), beta-caseins separate, resulting in soft cheese with high water content, which spoils quickly.
\nWhen acid is added to milk, calcium hydroxyl phosphate molecules change from an insoluble to a soluble form, and casein proteins reach the isoelectric state.
\nRennet is a proteolytic enzyme that cuts kappa-casein between amino acids 105 (phenylalanine) and 106 (methionine).
\nMacropeptide: Amino acids from 106 to 169 that are cut by rennet from kappa-casein and fall into the whey.
\nPara kappa-casein: Amino acids from 1 to 105.
\nFor whey protein precipitation, we use poly-electrolyte proteins (hydroxy-methyl cellulose) + pH and temperature change.
\nWhey protein:<\/strong>
\nWhey protein + macropeptides separated from casein protein.
\nSome whey proteins:
\nAlpha-lactalbumin: Precursor to lactase synthase enzyme.
\nBeta-lactalbumin: Only in cow’s milk, the main serum protein. When milk is heated, reactions occur between these two proteins and kappa-casein, and the enzyme cannot cut them.
\nImmunoglobulins: G1-G2-M-A
\nImmunoglobulin M plays the role of a clusterin or a binder of fat globules.
\nLactoferrin: Found in low levels in cow’s milk, contains iron.
\nProteose peptone: A type of pp3 unique to cows.
\nAlbumin.
\nOnce milk coagulates, it is irreversible.
\nBiocatalyst (enzyme) depends on two factors:
\nTemperature (ideal temperature 25-50)
\nand pH.
\nHigh temperatures (above 120) inactivate enzymes.
\nAlkaline phosphatase must be removed after pasteurization (pasteurization indicator for milk).
\nMilk enzymes:
\nPeroxidase: Produces oxidized substances with antimicrobial properties (LPS system).
\nCatalase.
\nPhosphatase: Breaks down alcohol and phosphoric acid compounds.
\nLipase: Causes undesirable sharp flavors.
\nProtease: Causes bitter cheese flavor (the group that works in neutral and alkaline pH is called plasmin).
\nMembrane lipase is activated in cold, but serum lipase is activated by stirring, thermal changes, and homogenization.
\nFor evaluating mastitis, catalase test is used.
\nIn mastitis, the number of lymphocytes increases, and catalase produced by lymphocytes is high.
\nLactose is formed by the union of glucose and galactose. It is the basis for fermentation industry and turns into lactic acid, which will make yogurt.
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