Dairy And Food Engineering

Step 1: Understanding the Concept:
Cheese is classified based on several factors, including moisture content (soft, semi-hard, hard) and whether it undergoes a ripening (aging) process. A hard, ripened cheese is one with low moisture content that has been aged for a period, allowing enzymes and microbes to develop its characteristic flavor and texture.
Step 3: Detailed Explanation:
- Cheddar cheese: This is the quintessential example of a hard, ripened cheese. It has a low moisture content (typically<39%) and is aged for several months to over a year, developing a sharp flavor and a firm, dense texture.
- Roquefort cheese: This is a semi-soft, blue-veined cheese. It is ripened, but it is not considered a hard cheese due to its higher moisture content.
- Cottage cheese: This is an unripened, fresh cheese. It has a very high moisture content and a soft, curdy texture. It is consumed fresh and is not aged.
- Camembert cheese: This is a soft-ripened cheese. It has a high moisture content and a soft, creamy interior that ripens from the outside in.
Step 4: Final Answer:
Among the given options, Cheddar cheese is the best example of a hard and ripened cheese. Therefore, option (C) is correct.

Step 1: Understanding the Concept:
Yoghurt production is a controlled process that transforms milk into a fermented dairy product. Each step is performed in a specific order to ensure the final product has the desired safety, texture, and flavor.
Step 3: Detailed Explanation:
The standard sequence for yoghurt manufacturing is as follows:
1. (B) Standardization of milk: The process starts with adjusting the milk's composition. This primarily involves modifying the fat and milk solids-not-fat (MSNF) content to meet legal standards and achieve the desired final texture.
2. (A) Homogenization of milk: The standardized milk is then homogenized by forcing it through small orifices under high pressure. This breaks down the fat globules, preventing cream separation and resulting in a smoother, more viscous yoghurt.
3. (C) Pasteurization, cooling followed by addition of starter culture: The milk is pasteurized at a high temperature (e.g., 85-95 C) to kill spoilage and pathogenic bacteria and to denature whey proteins, which helps create a more stable gel. The milk is then cooled to the optimal fermentation temperature (40-45 C) before the starter culture ({Lactobacillus bulgaricus} and {Streptococcus thermophilus}) is added.
4. (D) Fermentation, packaging and storage: The inoculated milk is incubated at the set temperature. During this time, the starter bacteria ferment lactose into lactic acid, causing the milk pH to drop and the casein proteins to coagulate, forming the characteristic yoghurt gel. After the desired acidity is reached, the yoghurt is cooled, packaged, and stored under refrigeration.
Step 4: Final Answer:
The correct chronological sequence of the steps is (B) (A) (C) (D). This matches option (C).

Step 1: Understanding the Concept:
The color of milk and milk fat is influenced by the diet of the cow. Certain pigments from the cow's feed are fat-soluble and can be transferred into the milk.
Step 3: Detailed Explanation:
- Carotenoids, particularly beta-carotene, are yellow-orange pigments found abundantly in green forage like grass, which is a major part of a cow's diet.
- Beta-carotene is a fat-soluble pigment. When consumed by the cow, it is absorbed and gets dissolved in the milk fat globules.
- This gives the milk fat a yellowish hue. The intensity of the color depends on the breed of the cow and the amount of green feed in its diet. This color is especially concentrated in products with high fat content, like cream and butter.
- Sterols, albumin (a protein), and phospholipids are other components of milk, but they are colorless and do not contribute to the yellow color.
Step 4: Final Answer:
The yellow color in cow's milk is caused by the presence of carotenoid pigments, primarily beta-carotene, dissolved in the milk fat. Therefore, option (D) is correct.