Milk Processing and Dairy Fermentation

• Milk processing involves several steps to ensure safety, quality, and preservation.
• Raw milk is first clarified to remove visible impurities and sediment.
• The milk is then pasteurized to eliminate pathogenic microorganisms and extend shelf life.
• Pasteurization typically involves heating milk to a specific temperature (e.g., 72°C for 15 seconds) followed by rapid cooling.
• Homogenization reduces the size of fat globules in milk to prevent creaming and improve texture.
• Milk can be separated into cream and skim milk using centrifugal force.
• Further processing steps may include evaporation to concentrate milk solids, drying to produce milk powder, and UHT treatment for extended shelf life.

Dairy Fermentation

• Dairy fermentation involves using microorganisms to convert lactose into lactic acid, altering the flavor, texture, and keeping qualities of milk.
• Common starter cultures include bacteria such as Lactococcus, Lactobacillus, and Streptococcus.
• Yogurt production involves fermenting milk with Streptococcus thermophilus and Lactobacillus bulgaricus.
• The fermentation process lowers the pH of the milk, causing the milk proteins to coagulate and thicken.
• Different strains of bacteria produce different flavor compounds, contributing to the diversity of yogurt types.
• Cheese making also relies on fermentation, with different cultures used to produce various cheese varieties.
• Fermented milk products include kefir, buttermilk, and sour cream, each with distinct flavor profiles and textures.

Cheese Making

• Cheese making involves coagulating milk, separating the curd from the whey, and then aging or ripening the curd.
• Milk coagulation can be achieved by adding rennet (an enzyme) or acid to the milk.
• Rennet coagulates milk by cleaving caseins, the main milk proteins, leading to the formation of a firm curd.
• Acid coagulation occurs at low pH, causing the proteins to denature and aggregate.
• Once the curd has formed, it is cut to release the whey.
• The whey is drained, and the curd is pressed to remove excess moisture.
• The curd is then salted to control microbial growth and enhance flavor.
• Cheese ripening involves enzymatic and microbial activity, which breaks down proteins and fats, resulting in the development of characteristic flavors and textures.
• Different cheese varieties require different ripening conditions and durations.

Quality Control

• Quality control in the dairy industry is essential to ensure product safety, consistency, and compliance with regulations.
• Raw milk is tested for antibiotic residues, somatic cell count, and bacterial load.
• Pasteurization and other heat treatments are validated using tests such as phosphatase tests to ensure effective pathogen inactivation.
• Finished products are analyzed for composition (fat, protein, moisture content), pH, and microbiological quality.
• Sensory evaluation, including taste, odor, and appearance, is performed to assess product acceptability.
• Quality control measures also include monitoring equipment performance, sanitation practices, and employee hygiene.
• Hazard Analysis and Critical Control Points (HACCP) systems are used to identify and control potential hazards throughout the dairy processing chain.
• Regular audits and inspections are conducted to verify compliance with food safety standards.

Dairy Packaging

• Dairy packaging serves to protect milk and milk products from contamination, light, and oxygen and to extend shelf life.
• Common packaging materials include glass, plastic (e.g., polyethylene, polypropylene), paperboard cartons, and metal cans.
• Packaging materials must be food-grade and inert to prevent interactions with the product.
• Aseptic packaging is used for UHT-treated milk and allows for extended shelf life without refrigeration.
• Modified atmosphere packaging (MAP) involves altering the gas composition within the package to inhibit microbial growth and enzymatic activity.
• Packaging design includes considerations for ease of handling, storage, and consumer convenience.
• Labeling provides information on product name, ingredients, nutritional content, and expiration date.
• Packaging should be environmentally sustainable, with increasing emphasis on recyclable and biodegradable materials.