Que 1: Write short note on salient Points to be Kept in Mind While Collecting and Transporting Raw Milk (CSE, 1981):
Ans:
Collection:
- Milk collection should be swift, with reception expedited within 3 to 4 hours, especially for large volumes.
- Timely collection prevents milk deterioration, reduces labor and operation costs.
- Incoming milk quality significantly influences the final product; it should be clean, sweet, and free from contaminants.
- Contamination with antibiotics, pesticides, and other chemicals is undesirable; abnormal milk should be rejected.
- Acid development indicates bacterial count and reduces heat stability; such milk should not be accepted.
- Grading based on organoleptic tests (odor, taste, appearance, acidity, sediment) is essential.
- Water adulteration should be checked using a lactometer and Gerber's test.
- Accurate samples must be collected for bacteriological and chemical examinations.
Transport:
- Choose appropriate transport modes; for short distances, use head load, shoulder sling, pack animals, bullock carts, bicycles, or cycle rickshaws.
- Larger quantities and longer distances may require lorries, rail or road-tankers.
- Within a 50 km radius, lorries can transport milk in ordinary cans; for a 100 km radius, chilling centers are needed.
- Prefer insulated milk tankers over cans for large quantities to minimize surface contamination and temperature issues.
- Restrict transport between collection centers and milk producers; use insulated milk tankers for transport to the plant.
Que2 : What do you understand by Pasteurization of Milk. Give different methods of Pasteurization.(CSE, 1981):
Ans:
Definition:Pasteurization involves heating every particle of milk to specific temperatures for designated durations to ensure safety and improve keeping quality.
Methods:
In-the-Bottle Pasteurization:Bottles held at 63.66°C for 30 minutes; not commonly used due to slow heat transfer and risks of bottle breakage.
Batch/Holding Pasteurization (LTLT):Milk heated to 63°C for 30 minutes and promptly cooled; three types - water-jacket, water-spray, and coil-vat.
High Temperature-Short Time (HTST) Pasteurization:
- Heated to 161°F for 15 seconds; plate heat exchanger widely used.
- Advantages: Quick treatment, lower initial cost, easily cleaned.
- Disadvantages: Not suitable for small quantities, gasket maintenance, milk stone accumulation.
Vacuum Pasteurization (Vacreation):
- Pasteurization under reduced pressure using direct steam.
- Designed for cream pasteurization; removes volatile flavors.
Stassination:Tubular exchanger with three concentric tubes; heats milk to 74°C for 7 seconds.
Ultra-High Temperature Pasteurization:Temperatures of 130-150°C for a fraction of a second; requires immediate aseptic packaging.
Uperization:Heated to 150°C for a fraction of a second with preheating steps; offers long keeping quality.
Que 3: Define Clarification, Homogenization, Pasteurization, and Sterilization of milk. Briefly narrate the principles involved in HTST and Holder methods of pasteurization. What is the acceptable Indian Standard Plate Count (per ml) for pasteurized milk at the plant in its final container? (CSE, 1990)
Ans:
Clarification of Milk:
Clarification of milk involves the process of separating the suspended solid particles, such as dirt, dust, and other impurities, from the milk. This is typically achieved using a cream separator or a clarifier, where the centrifugal force helps remove the particles.
Homogenization of Milk:
Homogenization is a mechanical process used to break down the fat globules in milk into smaller, more uniform sizes. This process ensures that the milk does not separate into cream and liquid, resulting in a smooth, uniform consistency.
Pasteurization of Milk:
Pasteurization is the process of heating milk to a specific temperature for a certain period of time to kill harmful pathogens without affecting the taste or nutritional value significantly. The process also helps in prolonging the shelf life of milk.
Sterilization of Milk:
Sterilization involves heating milk to a higher temperature (typically above 100°C) for a longer duration than pasteurization. This ensures the destruction of all microorganisms, including spores, thus making the milk microbiologically safe for long periods without refrigeration.
Principles of Pasteurization:
HTST (High-Temperature Short-Time) Method:
- In the HTST method, milk is heated to a temperature of 72°C (161.6°F) for 15 seconds and then rapidly cooled.
- The key principle is to kill harmful bacteria without significantly altering the taste or nutritional content of the milk.
- The process is faster than traditional pasteurization methods, which helps in maintaining the quality and extending the shelf life of the milk.
Holder Method:
- The Holder method (also called the Low-Temperature Long-Time or LTLT method) involves heating milk to 63°C (145.4°F) for 30 minutes and then cooling it rapidly.
- The principle behind this method is slower heating at lower temperatures, which still effectively kills harmful microorganisms, though it requires a longer time.
- While less efficient than HTST, the Holder method is often used in smaller operations or when milder heat treatment is desired to preserve more of the milk’s original properties.
Acceptable Indian Standard Plate Count (SPC) for Pasteurized Milk:
According to the Indian Food Safety and Standards Authority (FSSAI), the acceptable Indian Standard Plate Count (SPC) for pasteurized milk in its final container should be not more than 30,000 per ml. This count measures the number of viable bacteria present in the milk after pasteurization, indicating its microbiological quality.
Que 4. What are the problems in the collection and transportation of raw milk from rural to urban areas in India? How can these be overcome? (CSE, 1991)
Ans:
The collection and transportation of raw milk from rural areas to urban centers in India face several challenges. These problems, if unaddressed, can compromise the quality and safety of milk by the time it reaches consumers. Here’s an overview of the main issues and potential solutions:
1. Lack of Cold Chain Infrastructure
- Problem: Milk is a perishable product that requires refrigeration to prevent bacterial growth. In many rural areas, cold storage facilities and refrigerated transport are inadequate, causing spoilage during transit.
- Solution: Investment in a cold chain infrastructure, including refrigerated trucks and village-level chilling centers, can help maintain milk quality. Setting up solar-powered chillers in remote locations could be a sustainable option to address power shortages.
2.Inadequate Road and Transportation Facilities
- Problem: Poor road connectivity and unreliable transportation in rural areas lead to delays, affecting the freshness and quality of milk.
- Solution: Upgrading rural roads and improving transport services can facilitate faster milk collection. Additionally, organized collection routes and scheduled pick-ups can ensure timely milk transportation to urban centers.
3.Milk Adulteration
- Problem: In the absence of proper monitoring, there is a risk of milk adulteration at collection points or during transit, compromising milk quality and safety.
- Solution: Implementing strict quality control measures at collection centers, along with regular testing and monitoring, can reduce adulteration risks. Milk cooperatives can play a crucial role in standardizing quality checks before transport.
4.Insufficient Collection Points
- Problem: Limited milk collection points in rural areas force farmers to travel long distances to sell their milk, which can be time-consuming and may result in spoilage.
- Solution: Establishing more collection centers within reasonable distances can streamline the collection process, reduce travel time, and help maintain milk freshness.
5.Lack of Farmer Awareness and Training
- Problem: Farmers may lack awareness of the importance of hygienic practices in milking, handling, and storing milk, leading to contamination and quality degradation.
- Solution: Conducting training programs for farmers on hygienic milk production, proper handling, and storage practices can improve milk quality from the source itself.
6.Organizational and Logistical Challenges
- Problem: Inefficient collection and transportation logistics, especially in areas with scattered or small-scale producers, can hinder smooth milk transport.
- Solution: Developing cooperative societies or milk unions can organize milk collection more effectively, creating a more streamlined and efficient system of collection, storage, and transport to urban markets.
By addressing these challenges through infrastructure development, logistical improvements, quality control, and farmer education, the efficiency and quality of raw milk transportation from rural to urban areas in India can be significantly improved.
Que5: Discuss the processes involved in the manufacture of butter in a factory.(CSE 1987)
Ans:
The manufacture of butter in a factory involves several steps designed to separate, churn, and process cream to produce high-quality butter. Below are the key processes involved:
1. Milk Collection and Quality Control
- Fresh milk is collected from dairy farms and brought to the factory. Upon arrival, the milk undergoes quality testing for factors such as fat content, freshness, and purity. This ensures that only high-quality milk is used for butter production.
2. Cream Separation
- The collected milk is passed through a centrifugal separator to separate cream from skim milk. This is done by spinning the milk rapidly, which causes the heavier skim milk to move outward and the lighter cream to move inward.
- The separated cream, containing a higher percentage of fat, is then collected for the butter-making process.
3. Pasteurization of Cream
- The cream is pasteurized by heating it to around 85°C for 15–20 seconds to kill any harmful microorganisms, ensuring the butter’s safety and extending its shelf life.
- After pasteurization, the cream is rapidly cooled to prevent undesirable changes in flavor or texture.
4.Aging the Cream
- The pasteurized cream is then cooled to a temperature between 5°C and 10°C and allowed to age for several hours. This cooling process improves the texture and flavor of the butter by allowing the fat globules to crystallize.
- Aging also makes the churning process more efficient, resulting in better butter yield and quality.
5.Churning
- The aged cream is transferred to a churn or continuous butter machine where it undergoes vigorous agitation. This process separates the butterfat from the buttermilk.
- As the cream is churned, fat globules clump together to form butter granules, while the liquid buttermilk is drained off and collected as a byproduct.
6. Washing and Salting
- The butter granules are washed with cold water to remove any remaining buttermilk, which helps in preventing spoilage.
- Salt is often added to enhance flavor and act as a preservative. The amount of salt varies depending on consumer preferences and product specifications.
7.Kneading and Working
- The butter is then kneaded and worked to achieve a smooth, uniform texture. This process helps distribute salt evenly and expel any remaining water content.
- In some factories, this process is automated in continuous butter machines to ensure consistency and efficiency.
8.Packaging
- The finished butter is cut into blocks or formed into shapes, depending on the intended packaging.
- It is then packaged in appropriate materials to protect it from contamination and light, which can cause oxidation and spoilage. Butter is typically wrapped in foil or paper and stored under refrigeration.
9.Storage and Distribution
- The packaged butter is stored in refrigerated conditions to maintain freshness and prevent microbial growth until it is transported to retailers or consumers.
These processes ensure that butter produced in a factory is of high quality, safe for consumption, and has a desirable texture and flavor.
