Additional Topics-1 | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Whey and Whey Products

• Whey is the leftover product obtained after most of the casein and fat are removed from milk. It is a by-product of cheese and casein production.
• Whey contains a significant amount of albumin, lactose, and mineral matter from the milk. It is often condensed or dried for animal feed, particularly in poultry farming due to its high lactose and riboflavin content.
• The yield of whey in cheese-making is approximately 90 pounds per 100 pounds of milk.

Average Composition of Whey Products

• Water: 93.0%
• Protein: 55.5%
• Fat: 6.0%
• Lactose: Usually soft and smooth, varying percentages
• Ash: Ranges from 0.5% to 10.4%
• Lactic acid: Varies from 0.6% to 2.9%

Special Uses of Whey

• Specially prepared whey is utilized to feed typhoid patients due to its properties.
• Whey serves as a primary source of commercial milk sugar, highlighting its importance in various applications.

Butter-Milk (Creamery)

Definition

• Genuine buttermilk is the liquid remaining after the fat is separated from milk or cream through churning in butter production.

Composition and Nutritive Value

• If butter is made from sweet cream or milk, the resulting buttermilk is similar to ordinary skim milk.
• When sour milk or cream is churned, lactic acid and less milk sugar are present compared to sweet cream butter-milk.
• In sour cream butter-milk, 10 to 15% of the sugar is converted into lactic acid.
• For every 100 lbs of butter produced, 166 lbs of buttermilk is obtained.
• Genuine buttermilk, despite having lower fat and vitamin A content, has a composition and nutritive value similar to milk.
• During churning, butter-milk retains a significant portion of phospholipids associated with fat globules, making it a valuable source of phosphorus.

Composition of Butter-Milk

• Sweet Cream: Composition varies.
• Sour Cream: Composition differs due to the presence of lactic acid.

Average Composition of Butter-Milk

• Type of Butter-Milk
• Sweet cream
• Sour cream

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Lactose

• Composition:
  • Water - 90.83% to 91.30%
  • Protein - 3.45% to 3.40%
  • Fat - 0.55% to 0.65%
  • Lactose - 4.40%
  • Ash - 0.73% to 0.65%
  • Lactic acid - 0.04% to 0.60%
• Forms of Lactose: Lactose can exist in two crystalline forms, α and β, as hydrate or anhydride. The most common form is 2-lactose hydrate, considered the commercial form.
• Sources of Lactose: The primary source of lactose in major cheese-producing countries is cheese whey. In India, chhana-whey is a significant source, but its collection from small-scale producers needs better organization.
• Grades of Lactose: Crude, edible, and USP are common grades. Crude lactose has impurities and is refined to USP grade. Edible grade, with fewer impurities, is suitable for infant foods. USP grade meets high purity standards for pharmaceutical and infant feeding purposes.
• Specifications: Specific requirements for lactose grades include lactose percentage, moisture, protein, ash, lipids percentage, acidity as lactic percentage, and microbial counts.

Casein

• Composition:
  • Crude - 98.4%
  • Edible - 99.0%
  • USP - 96.85%
• Requirements: Different grades have specific purity criteria, with USP grade meeting the highest standards.
• Manufacturing Process: Lactose is separated from whey through concentration and crystallization, removing impurities like whey proteins and salts to ensure purity in the final product.
• Uses of Lactose: Lactose finds applications in humanized milk, infant food, pharmaceutical preparations like pills, tablets, and bakery products.

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Summary: Industrial Casein Production

Overview

• Skim milk is used to produce industrial casein, a non-food product in high demand globally.
• Two main types of industrial casein are acid casein and rennet casein, each with distinct uses.

Types of Casein

• Based on coagulating agents:
  • Acid casein
  • Rennet casein
• Based on the particular acid used:
  • Hydrochloric acid casein
  • Sulphuric acid casein
  • Nitric acid casein
  • Lactic acid casein
• Based on the texture of the curd:
  • Grain curd casein
  • Cooked curd casein
  • Pressed curd casein

Principle of Manufacture

• Process involves receiving skim milk, precipitating, draining, washing, pressing, milling, drying, grinding, packaging, and storage.

Uses of Industrial Casein

• Rennet-casein uses:
  • Plastics (e.g., buckets, buttons)
• Acid casein uses:
  • Adhesive (glue), paper coating, paint, fibers, bristles, films, and more.

Caselin (Edible)

• Edible casein is isolated from skim milk for use in food and pharmaceutical products.

Preparation of Edible Casein

• Preparation method similar to acid casein production
• Special precautions include:
  • Precipitation of the curd at pH 4.1 to 4.3
  • At least 3 separate washings of the curd in waters of proper pH with 15-20 minutes contact time each
  • Last but one washing with hot water at 71-77°C (160-170°F) for pasteurization of the curd
  • Last washing with neutral water at 41°C (105°F)

Uses of Edible Casein

• Edible casein, in its original form or as sodium caseinate, is utilized in various food products such as:
• Ice-cream
• Coffee whiteners
• Imitation milk
• Whipping powders
• Instant breakfast
• Water binders in sausages
• Protein hydrolysates

Testing and Standards

• Testing, grading, and judging of milk products involve adherence to ISI and Agmark specifications
• Legal standards, quality control, nutritive properties, packaging, processing, and operational control are important aspects
• Additional information on packaging is provided under "Packaging of Milk and Milk Products" in the subsequent pages

Summary: Butter Oil

I. Definition of Butter Oil:

• Butter oil is a concentrated fat derived mainly from butter or cream after removing water and solids-not-fat content. It is also known as milk fat, anhydrous miniat, dry butter fat, or dehydrated butter fat, with cream being the usual raw material.

II. Composition of Butter Oil:

• Butter oil typically contains 99.5 to 99.8% butter fat, 0.1 to 0.3% moisture, acidity (oleic) between 0.2 and 0.5%, and peroxide value ranging from 0.0 to 0.1%.

III. Food and Nutritive Value:

• Butter oil is a rich source of milk fat in Western dairy products, high in fat-soluble vitamins A and D.

IV. Methods of Manufacturing Butter Oil:

• Various methods include:
  • Direct evaporation
  • Decantation
  • Centrifugation followed by vacuum drying
  • Direct from cream by de-emulsification and centrifugation

A. Direct Evaporation:

• Direct evaporation can be carried out as a batch process at atmospheric pressure or under vacuum, resembling the Indian method of ghee production.
• In this method, butter is heated in a large open vat/pan using a steam jacket.

Butter Manufacturing Processes

• Traditional Butter Making Processes

  • Churning: Initially, heat is applied gradually until the butter melts and then the temperature is raised while stirring until it reaches about 108 to 110°C (226-230°F).
  • Decantation: Butter is melted and allowed to stratify into layers, but this method leads to lower fat recovery and is not efficient for large-scale production.

• Modern Continuous Process

  • Centrifugal Separation and Vacuum Drying:
    • A continuous method involving the use of centrifugal separation followed by vacuum drying, resulting in a higher quality product.
    • Butter is melted and then separated into oil and serum through a series of steps including oil separation, dehydration, and cooling.
  • Direct Anhydrous Milk Fat Production: Utilizes de-emulsification and centrifugation principles, although commercial application is limited.

• Cooling and Storage

  • Cooling Process:
    • Butter oil should be cooled and crystallized under controlled conditions to form fine crystals, ensuring a smooth and homogeneous mass.
    • Rapid super cooling and stirring during crystallization contribute to the desired texture.
  • Packaging, Storage, and Distribution:
    • Proper packaging is essential to exclude oxygen and prevent re-aeration of the product.
    • Storage conditions impact the flavor of butter fat, with antioxidants like ethylgallate extending shelf life.
    • Distribution usually occurs in the original packaging under atmospheric conditions, with attention to market quality.

Factors Influencing the Quality of Butter Fat

• Copper and Iron Content:
  • Higher levels of copper and iron speed up fat oxidation, leading to a rancid flavor.
  • Ideal copper content in butter fat should not exceed 0.02 - 0.03 ppm, and iron content should stay below 0.10 ppm.
  • Equipment used for butter oil production should be stainless steel or well-tinned copper and iron vessels to maintain quality.
• Amount of Air Present:
  • Fat absorbs oxygen from the air, affecting its keeping quality.
  • Vacuumizing and gas packing are recommended to enhance keeping quality, with oxygen levels ideally below 0.5 ppm.
  • Storing butter fat in nitrogen further preserves its quality.
• Holding Temperature:
  • De-aerated and sealed butter oil maintains quality within normal temperature ranges.
  • Storage at cold temperatures (5-10°C) is optimal to slow down oxidation.
• Light Exposure:
  • Exposure to light, particularly sunlight, can bleach fat and cause tallowiness.
  • Butter oil should be stored in a cool, dark place to prevent quality deterioration.
• Method of Manufacture:
  • Butter oil's quality depends on the production process, with direct evaporation yielding better keeping quality than other methods.
• Initial Quality of Butter Fat:
  • Butter oil from sweet cream butter exhibits superior storage quality compared to other sources.

Preservation and Grading of Butter Oil

• Preservatives:
  • Antioxidants like NDGA, ethyl gallate, and hydroquinone delay oxidation in butter oil.
  • These antioxidants prevent the chain reaction of fat oxidation, maintaining product quality.
  • Legislation in some countries may restrict the use of antioxidants.
• Grading Procedure:
  • Examination of container cleanliness, aroma, color, texture, and taste to assess quality.
  • Acidity, moisture, and peroxide value tests determine the grade of butter oil.
• Requirements of High-Grade Butter Oil:
  • Clean, bright packaging with deep yellow color for cow fat and white with a greenish tinge for buffalo fat.
  • Desirable characteristics include a fine crystalline texture, pleasant smell, and butter-like aroma.
• Score-card:
  • Parameters like flavor, texture, acidity, color, and packaging are evaluated to grade butter oil quality.
  • Defects such as brownish color and coarse texture impact the overall score.

Understanding Defects in Butter Oil: Causes and Prevention

Defects in butter oil can arise from various factors, such as the quality of milk, cream, or butter used, as well as faulty production, processing, and storage methods.

Common Defects in Butter Oil

• Presence of overheated fine curd particles

Causes

• Improper filtration in direct evaporation methods

Prevention

• Adopting the clarification-cum-vacuum method of production

Factors Affecting Butter Oil Quality

One key factor that influences the quality of butter oil is the rate of cooling after production. For instance, a slow cooling rate can lead to certain defects.

Example

For example, if butter oil is allowed to cool too slowly after production, it may result in the formation of undesirable particles, affecting the overall quality of the product.

Optimal Cooling Practices

To ensure the quality of butter oil, it is important to implement fast cooling practices immediately after production.

Summary

Defects in butter oil can be prevented by addressing the root causes through proper production methods and fast cooling practices. By understanding these factors, producers can maintain the quality and integrity of their butter oil products.

Condensed Notes on Butter Oil

Overview:

• Butter oil can develop undesirable flavors such as rancid, oxidized, metallic, or tallowy due to processes like fat hydrolysis and oxidation.

Causes of Undesirable Flavors:

• Butter oil can develop off-flavors due to fat hydrolysis by lipase in milk, cream, or butter.
• Fat oxidation can occur when butter oil comes in contact with copper or iron, or when exposed to sunlight.

Prevention and Storage:

• Inactivate lipase through proper pasteurization of milk or cream.
• Store milk, butter, or butter oil in adequately tinned or stainless steel vessels.
• Vacuumize or gas-pack butter oil to prevent oxidation.
• Add antioxidants to butter oil before packaging.
• Store butter oil in opaque containers to maintain quality.

Uses of Butter Oil:

• Butter oil is utilized in various ways including recombined milk production, butter reconstitution, ice-cream making, cooking fat, confectionery, and fat spread manufacturing.