Microbial spoilage of milk and milk product
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This document discusses microbial spoilage of milk and milk products. It notes that dairy products are susceptible to spoilage due to their high nutritional content, water activity, and moderate pH. Common spoilage microorganisms include psychrotrophs during refrigerated storage, thermoduric microorganisms after pasteurization, and molds/yeasts after heat treatment. Sources of contamination include milking animals, equipment, and the surrounding environment. Spoilage can result in off flavors, rancidity, gas production, souring, texture changes, and discoloration. Specific microorganisms are associated with defects in products like pasteurized milk, cream, butter, cheese, and yogurt.
Microbial spoilage of milk and milk product
- 1. Microbial Spoilage of Milk and Milk Product
- 2. Microbial Spoilage of Milk product ⬩ The loss of quality of milk and its product for its consumption due to the microbial growth or any other microbial product is known as Microbial spoilage of milk product. 2
- 3. Microbial spoilage of Milk and Milk Product • Dairy products such as milk, butter, cream and cheese are all susceptible to microbial spoilage due to their high nutritional composition (Protein, Carbohydrate, Fats, Minerals, Lactose sugar, citrate and nitrogenous compounds) high water activity and moderate pH (6.4-6.6) Limited self life 3
- 4. 4 Condition of spoilage Type of mos Examples of mos During refrigerated storage psychrotrophs Pseudomonas, Flavobacterium, Alcaligenes, Listeria monocytogenes, Yersinia enterocolitica, some coliforms, and Bacillus spp. After pasteurization thermoduric microorganisms Enterococcus, Streptococcus, some Lactobacillus, and spores of Bacillus and Clostridium spoilage after the heat treatment Molds and yeasts Aspergillus, Byssochlamys, Cladosporium, Candida spp.
- 5. The source of milk contamination are: ⬩ the contamination from milking animals ⬩ the interior and exterior of the udder ⬩ the coat of the milking animals ⬩ the surrounding air of the farm and storage ⬩ the animal feed ⬩ the quality of water used ⬩ the quality of milk handling equipment and storage tanks used ⬩ biofilms formation on diary plant pipes 5
- 6. Defects that occur in milk and milk products ⬩ Off flavor ⬩ Lipolysis with development of rancidity ⬩ Gas production ⬩ Fermentation to lactic acid with souring ⬩ Coagulation of milk protein / Proteolysis ⬩ Viscous or ropy texture ⬩ Discoloration 6
- 7. 7 S. N Milk Product Defect Microorganisms 1 Pasteurized Milk Rancid Peudomonas, Alkaligenes, Staphylococcus Ropy or Slimy Pseudomonas, Alkaligenes, Coliforms, Bacillus Subtilis Sour Lactic acid Bacteria Bitter or Fruity Peudomonas, Alkaligenes, Proteus, Flavobacterium Discoloration Chromobacterium
- 8. 8 S. N Milk Product Defect Microorganisms 2. Creamed Milk Swelling, Gas Clostridium, Sporogenes 3. Cream Foamy Candida, Torulopsis 4. Butter Surface taint Pseudomonas, Alteromonas
- 9. 9 S. N Milk Product Defect Microorganisms 5 Cheese Gassy, Butyric acid Clostridium tyrobutyrcium Moldy Penicillium, Scopulariopsis, Mucor Gassy Floating or split curd Leuconostoc, Streptococcus lactic 6 Soft Cheese Black mold Mucor Surface growth Torulopsis, Debaryomyces
- 10. 10 S. N Milk Product Defect Microorganisms 7. Yoghurt Yeasty Yeast (Torulopsis)