Cheese | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Cheese Production

• Cheese as a Preservation Method

  Cheese production serves as a method to preserve milk for future sale.

• Transportation Benefit

  Cheese can be transported when there are limitations in transporting fluid milk, with minimal loss of milk's nutritive value.

• Role in Dairy Industry

  Cheese, similar to butter, plays a crucial role in balancing the dairy industry in developed countries.

• Cheese Production in India

  In India, only a small amount of milk is annually converted into cheese, primarily cheddar.

• Historical Context of Cheese in India

  In the past, cheese production was not popular in India due to religious beliefs preventing the use of animal rennet for milk coagulation.

  • Plant-Based Coagulant

    Indians discovered Withania coagulans, a plant whose seeds coagulated milk, aiding in the limited production of Indian cheese or paneer.

  • Development of Bacterial Rennet

    The National Dairy Research Institute in Karnal has developed bacterial rennet from specific strains of Bacillus subtilis.

  • Challenges in Industry Growth

    The non-acceptance of rennet by a significant portion of the population, along with a lack of taste for cheese, has hindered the growth of the cheese industry in India.

• Fat Content

  Cheese typically contains around 90% fat.

Cheese Making and Standards Overview

• Cheese Making Process

  • Cheese production involves recovering and preserving milk constituents like milk fat and proteins.
  • In cheese making, milk is coagulated using rennet, curd is formed, whey is removed through heating and acid development, and the final product is shaped and packed.
  • Cheese primarily consists of proteins (mainly casein), salts (e.g., colloidal calcium phosphate), lactose, and micro-organisms.

• Cheese Types

  • Two main categories of cheese are hard (e.g., cheddar) and soft (e.g., cottage cheese).
  • Hard cheeses have low moisture content and better shelf life, while soft cheeses have higher moisture and are meant for immediate consumption.

• Cheese Standards

  • Hard cheese, as per PFA Rules, should be produced from milk coagulation with specific additives and cultures, meeting defined moisture and fat content limits.
  • Indian Standards Institution specifies requirements for natural cheese varieties, processed cheese, and cheese spreads, including criteria for moisture, fat, casein, and salt content.

• Example of Hard Cheese

  • Cheddar cheese is a typical example of hard cheese, characterized by specific composition standards.
  • American cheddar cheese composition includes defined limits for moisture, fat, and optional additives.

Cheddar Cheese: Origin, Nutritional Value, and Manufacturing Process

• Cheddar cheese has its roots in the town of Cheddar, situated in the county of Sornnreot in South-westora England. It is renowned worldwide and has various versions like American, Australian, New Zealand, Canadian, and Indian Cheddar.
• Food and Nutritional Value:
  • Rich in milk proteins, calcium, and phosphorus.
  • Abundant in fat-soluble vitamins A, D, E, and K.
  • High in energy, providing around 400 calories per 100 grams.
  • Pleasant to taste and easy to digest with minimal wastage.
• Manufacture of Cheddar Cheese:
  • Flow Chart of Manufacture:
    • Receiving and preheating milk.
    • Filtration and clarification of milk.
    • Standardizing milk.
    • Pasteurization at 63°C for 30 minutes.
    • Adding starter culture at 31°C.
    • Incorporating color.
    • Introducing rennet for coagulation at 31°C.
    • Coagulation and curd setting.
    • Cutting the curd.
    • Cooking the curds at 37-39°C.
    • Draining the whey.
    • Cheddaring process.
    • Milling the curds.
    • Salting the cheese.
    • Shaping the cheese in hoops.
    • Dressing the cheese.
    • Pressing the cheese.
    • Drying and paraffining the cheese.
    • Curing and maturing the cheese.

Details of Cheese Manufacture Process

• Receiving, preheating, and filtration/clarification are initial steps common in fluid milk processing.
• Standardization of milk fat percentage is crucial for cheese quality.
  • A higher fat content yields a soft velvety cheese, while lower fat content results in a hard, leathery texture.
  • Optimal fat to casein ratio of 1:0.70 in standardized milk ensures desired fat content in cheese.
• Starter addition:
  • Starter is added for acid development at 31°C to aid rennet clot formation.
  • Proper acidity levels are essential for renneting, with fresh starter acidity around 0.75%.
  • Insufficient starter can lead to issues like wrinkled curd, high moisture, and off-flavors in cheese.
• Quality concerns:
  • Issues in cheese batches may be due to milk quality or faulty starters.
  • Bacteriophage contamination can affect all vats in the factory.
• Renneting process:
  • Milk is heated to 31°C for renneting, stirred until optimal acid levels (0.20% lactic acid) are achieved.
• Color addition:
  • Color is added before renneting, typically 30-200 ml per 1000 liters of milk.
  • Color is diluted for uniform distribution and should not be mixed with rennet before adding to milk.

Adding Rennet

• The ideal temperature for adding rennet to pasteurized milk is 31°C.
• Amount of rennet added depends on its strength, typically 15 to 25 ml per 1000 liters of milk.
• Rennet is diluted with potable water before addition for uniform coagulation.
• Rennin action releases K-casein from casein, leading to clot formation.

Coagulation and Curd Cutting

• Coagulation completes in about 30 minutes.
• Curd is cut into cubes using wide knives, then kept floating in whey and gently stirred.

Curd Cooking and Whey Draining

• Cooking involves heating curd cubes gradually to 37-39°C.
• Whey draining is done at the pitching point to settle curd at the vat bottom.

Matting and Cheddaring

• In matting, curd is packed with space for whey drainage.
• Cheddaring involves cutting curd into blocks, piling them with cloth for drainage.
• The curd develops a nutty aroma and is ready for milling after cheddaring.

Salting Process of Cheddar Cheese

• Salt is added to curd at a rate of 1 to 2 percent, with an average of 1.5 percent.
• The curd is left for about seven hours after the starter is added before being put in the press.

Hooping, Dressing, and Pressing

• After salting, the curd is mixed well, then filled into cloth-lined hoops or moulds under hand pressure.
• Cheese is pressed for 14 to 16 hours, with pressure steadily increasing.
• Dressing involves arranging the cheese cloth before and after pressing.

Drying and Paraffining

• After pressing, the cheese is dried at 10 to 15°C with a humidity of 70 to 75%.
• Cheese is turned daily until paraffined at 125 to 130°C to reduce moisture loss, prevent mold growth, and protect against insects.
• Cheddar cheese typically reaches its characteristic flavor in about 3 months and can be consumed from 3 months up to a year or longer.

Changes in Cheddar Cheese During Manufacture and Ripening

Changes During Manufacture

• The number of starter organisms in the cheese increases to 1 or 2 billion per gram by the next morning.
• Acid development is rapid between dipping and milling the curd.
• The raw cheese's pH after 3 days of manufacture ranges from 5.05 to 5.20.
• All remaining lactose is consumed by the starter organisms shortly after manufacture.

Changes During Ripening

• Within 2 to 4 weeks at 7°C, cheddar cheese loses firmness and elasticity.
• Proteins convert to water-soluble compounds like proteases and peptones, reducing firmness.
• In the initial 10 weeks, about 25.18% of proteins are transformed, leading to the development of cheddar cheese flavor.
• By 28 weeks, 33% of the proteins become soluble, enhancing the typical cheddar cheese taste.

Cheese Production Overview

• Cheese Flavor Development

  • During cheese production, lactose is converted to lactic acid, which further transforms into compounds like biacetyl, acetic acid, and n-butyric acid.
  • Fat hydrolysis in cheese releases acids such as n-butyric, caproic, caprylic, and capric acids.
  • The background flavor of cheese comes from elements like peptones, lactic acid, and sodium chloride.
  • Glutamic acid, among amino acids, plays a significant role in cheese flavor.
  • Sharpness in flavor is attributed to compounds like ammonium butyrate.

• Microbial Succession in Cheese

  • Microorganisms in cheese undergo a series of changes during ripening.
  • The number of starter organisms decreases, releasing enzymes for protein breakdown.
  • Lactobacilli gradually outnumber starter organisms, with Lactobacillus casei developing slowly in pasteurized milk.
  • In raw milk cheese, non-lactic bacteria like micrococci are present and can impact flavor through lipolytic changes.

• pH and Ripening

  • The pH of cheese fluctuates during ripening, starting around 5.05 and increasing to 5.58 over 24 months.
  • pH is crucial for the development of flavors and texture in cheese.

• Protein Changes and Ripening Index

  • Protein breakdown, especially casein and B-lactoglobulin, is essential during cheese ripening.
  • Ripening index is a key measurement to assess the rate of cheese ripening.

• Cheese Constituents Distribution

  • Table 12 provides insights into the distribution of milk constituents in cheddar cheese and whey.
  • Casein and fat are retained in cheese, while lactose and whey proteins are drained in whey.

• Packaging and Storage

  • Cheese packaging includes long-term options like waxed cellulose and nylon films, as well as short-term options suitable for retail sale.
  • Proper storage at low temperatures, ideally 0 to 1°C, is crucial to maintain cheese quality and prevent spoilage.

• Judging and Grading Cheese

  • Legal and ISI standards govern the judging and grading of cheese.
  • A scorecard developed by the American Dairy Science Association aids in assessing and grading cheese quality.

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Score Card for Cheddar Cheese (ADSA)

• Flavour and Aroma
• Body and Texture
• Finish and Appearance
• Colour
• CAS
• Total
• Perfect Score: 100

Requirements for High-Grade Cheddar Cheese

• Flavour: Clean, pleasing aroma; mildly salted taste; leaves a pleasant aftertaste resembling sweet nuts.
• Body: Slightly elastic, breaks slowly when bent, firm but not hard when crushed.
• Texture: Compact, continuous, homogeneous, free from openings or cracks.
• Finish and Appearance: Smooth, unbroken rind, neat, clean, attractive appearance.
• Colour: Uniform, light amber to ivory.

Cheese-Making Process

The conventional batch process for making cheddar cheese is time-consuming and labor-intensive. Continuous cheese-making equipment has been developed to streamline the process.

Cottage Cheese

Cottage cheese is a soft, unripened variety often made from skim milk. It can be marketed plain or mixed with cream, pineapple, or other fruits.

Manufacturing Details

• Good pasteurized milk is inoculated with lactic cultures containing specific bacteria.
• Rennet extracts can be added in small quantities if desired.

Setting the Curd

There are two methods for setting the curd: short setting process and long setting process, each influencing the cheese's aroma and texture.

Processing and Storage

After curdling and cooking, the curd is washed, salted, and stored. Cottage cheese can be stored for a limited time, with specific precautions needed to prevent defects.

Important Faults of Cottage Cheese

• Lack of aroma and contamination with specific organisms can impact the quality of cottage cheese.
• Proper handling and hygiene practices can help eliminate defects caused by certain bacteria.

Indian Standard Specifications for Soft Cheese

Detailed standards for soft cheese are outlined in IS: 2785, 1979, providing guidelines for quality and production.

Processed Cheese and Related Products

Processed cheese involves heating cheese with emulsifiers and stabilizers, with specific regulations on ingredients and moisture content.

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Processed Cheese: Methods and Advantages

• Content Requirement and Chemical Composition

  • Processed cheese must contain at least 40% dry matter.
  • Additives like sorbic acid or nicin can be included in limited amounts.

• Advantages of Cheese Processing

  • Enhances product shelf life.
  • Allows for blending cheeses of different ages to achieve consistent characteristics.
  • Enables the creation of various blends by combining different cheese varieties.
  • Destroys harmful organisms, ensuring safety for consumption.

• Manufacturing Process

  • Selection and Blending: Quality cheeses at different ripening stages are chosen, comminuted, and placed in steam-jacketed kettles.
  • Addition of Ingredients: Chemicals are used to dissolve proteins, emulsify fat, and add flavorings. Emulsifying agents should not exceed 4% of the cheese weight.
  • Processing: Heat treatment at a minimum of 66°C for at least 30 seconds.
  • Filling: Filling processed cheese into foil-lined containers and sealing to preserve freshness.

• Related Products

  • Pasteurized Blended Cheese: Produced without acid and emulsifying agents.
  • Pasteurized Process Cheese Food: Standards include moisture below 44% and minimum fat content of 23%.
  • Processed Cheese Spread: Prepared by mixing hard cheeses into a spreadable mass with added ingredients.

Cheese Manufacturing Process Overview

• Introduction to Cheese Production

  When processed cheese and related products undergo heating and scaling, spoilage often occurs due to anaerobic bacteria. Specifically, Clostridium sporogenes is responsible for putrefaction in cheese production. Notably, both Clostridium pasteurianum and Clostridium sporogenes are gas-producing bacteria.

• Small-Scale Cheese Manufacturing

  French scientists have developed an automated miniature cheese making plant that can produce cheese products in small quantities using 10-50 litres of milk under controlled conditions. This plant aims to replicate industrial production conditions as closely as possible.

  • Components of the System

    The cheese production unit comprises four small oblong 12-litre stainless steel tanks. Parameters such as temperature, coagulation, and mechanical processes in the tank are monitored to ensure optimal production conditions. Additionally, factors like the pH of the milk and whey, as well as the weight of the milk and other constituents, can be easily measured.

  • The Pressing Unit

    Pressing occurs in two 0.5 m³ cells, each equipped with two compressed air presses (0.2 bar). Temperature and mechanical pressing conditions are closely monitored using sensors. The chambers housing the presses are thermostatically controlled between 5-6°C, with a controlled temperature increase of 1°C per minute to mimic industrial cheese making conditions.

  • The Refining Unit

    Refining is conducted in three cells, each with 12m³ of usable space. Two cells are cooled by a water/glycol mixture, while one is cooled by direct expansion. Temperature and humidity levels are regulated by self-adapting microprocessors, considering the material quantity in the cells. Key refining parameters such as CO₂ and NH₃ concentrations in the cell atmosphere are continuously monitored and controlled using infrared analyzers.

Automated Miniature Cheese Making Plant

Rennet: Definition and Preparation

• Rennet is a crude extract from the abomasum of young calves, containing rennin and pepsin enzymes.
• Rennin is a powerful clotting enzyme, while pepsin induces proteolysis in cheese.
• Rennet is available in liquid, powder, or tablet forms.
• Rennet is prepared by macerating the stomach lining in water with boric acid or through brine extraction.

Storage and Properties of Rennin

• Commercial rennet should be stored below 10°C and not lose more than 1-2% strength per month.
• Properties of rennin include being a sulfur-containing protein, clotting milk efficiently, and being sensitive to heat and alkali.
• Rennin is easily destroyed by heat, certain chemicals, and specific pH conditions.
• The optimal temperature for rennin's action is 41°C.

Application in Cheese Making

• Liquid rennet, containing about 2% protein, is used in cheese making at a specific ratio with milk.
• Rennin can clot a vast amount of milk, making it essential for the cheese-making process.
• Its sensitivity to various conditions underscores the need for careful handling during cheese production.