Condensed Milk | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Condensed Milk Overview

• Definition: Condensed milk refers to products created by evaporating part of the water from whole milk or fully/partially skimmed milk, with or without sugar.
• Types:
  • Sweetened Condensed Milk: Typically made from full-cream milk with added sugar.
  • Evaporated Milk: Generally made from full-cream milk without added sugar.
  • Sweetened Condensed Skim Milk: Produced from skimmed milk with added sugar.
  • Unsweetened Condensed Skim Milk: Made from skimmed milk without added sugar.
• Concentration Ratio: The ratio of milk solids concentration is around 1:2.5 for full-cream products and 1:3 for sweetened condensed skim milk.

Sweetened Condensed Milk Composition

• Ingredients: Cow or buffalo milk, or a mix, with added cane sugar, refined lactose, calcium chloride, citric acid, and sodium citrate, among other possible additives.
• Minimum Requirements:
  • Milk Fat: Not less than 9.0%.
  • Total Milk Solids: Not less than 31.0%.
  • Cane Sugar: Not less than 40.0%.
• Permissible Additives: Certain additives like orthophosphoric acid and polyphosphoric acid, up to 0.3% by weight of the final product, are allowed without needing declaration on the label.

Condensed Milk Overview

• Sweetened condensed skim milk is derived from cow or buffalo skimmed milk with water partially removed and cane sugar added.
• Additional ingredients may include refined lactose, calcium chloride, citric acid, sodium citrate, and sodium salts of orthophosphoric acid and polyphosphoric acid, not exceeding 0.3% of the final product's weight.
• Minimum requirements for sweetened condensed skim milk: 26.0% total milk solids, 40.0% cane sugar, and a maximum of 0.5% fat by weight.

Composition of Condensed Milk Types

• Condensed Milk
  • Composition: 26.0% solids, 74.0% water, 9.0% protein, 22.0% fat solids not fat.
• Skimmed Condensed Milk
  • Composition: 29.0% solids, 71.0% water, and maximum 0.5% fat.

Characteristics of Condensed Milk

• Total milk solids minimum: 25.5% by weight
• Fat content: 8.3% by weight
• Minimum sucrose content: 19.3% by weight

Indian Standard Specifications for Condensed Milks

• Specified by IS: 1166, 1973
• For condensed milk:
  • Minimum 9.0% total milk solids
  • Minimum 40% sucrose
• For skim sweetened milk:
  • Maximum 0.5% fat content

Food and Nutritive Value of Condensed and Evaporated Milks

• Acidity (lactic) maximum: 0.35
• Bacterial count (per gram) maximum: 500
• Coliform count (per gram): Negative
• Yeast and mold count (per gram) maximum: 10

Key Points:

• Both condensed and evaporated milks have high nutritive value.
• They are rich in fat, fat-soluble vitamins A, D, E, and K, body-building proteins, bone-forming minerals, and energy-giving lactose.
• Condensed milk is particularly high in energy-giving sucrose.
• Evaporated milk is highly suitable for infant feeding as it is a homogenized and sterilized product that forms a soft curd easily digested by infants.

Loss of Vitamins:

• There is a loss of vitamin B1 (30-50%) and vitamin C (50-100%) due to sterilization in evaporated milk.
• However, milk is generally a poor source of vitamin C.

Effect of Sterilization:

• Sterilization has a minor impact on the biological value and digestibility of milk proteins.

It is essential to understand the nutritional benefits of condensed and evaporated milks to make informed decisions about their consumption.

Manufacture of Condensed Milk

• Receiving Milk

  • Raw milk must meet high standards for stability determined by acidity and salt balance.
  • Alcohol test helps detect abnormal milk types like colostrum or milk with mineral imbalance.
  • Positive alcohol test indicates unsuitability for condensed milk production.
  • Minimum MBR time required is 3.5 hours.

• Filtration/Clarification

  • Done at 30-40°C to remove visible foreign matter.

• Standardisation

  • Adjust fat to milk solids-not-fat ratio desired in the final product.
  • Add cream for low butter fat content and skim milk for high fat content.

• Preheating

  • Preheating reasons: microorganism and enzyme destruction, viscosity prevention.
  • Modern preheating at 116-118°C with no holding time.

• Addition of Sugar

  • Use pure sugar to preserve milk without sterilization.
  • Sugar ratio affects osmotic pressure and product stability.
  • Optimal temperature and time of sugar addition impact product quality.

• Condensing Process

  • Boiling milk injurious at 100.15°C, thus done in partial vacuum.
  • Vacuum condensing removes water quickly without cooked flavors.
  • Finished product judged by appearance and density.

Condensed Milk Processing and Packaging

• Cooling and Crystallization

  • Prompt cooling after condensation is essential to prevent age-thickening and discoloration.
  • Improper cooling can lead to the development of sandiness in the product within 12-24 hours.
  • The presence of large lactose crystals causes sandiness, affecting the smoothness of the condensed milk.
  • To maintain a smooth consistency, around 400,000 lactose crystals per cubic millimeter are necessary.
  • Preventing the formation of large crystals involves inducing mass crystallization of small crystals by adding a small amount (0.1 to 0.3%) of fine lactose crystals known as 'seed lactose'.

• Packaging

  • Bulk packaging options include barrels, drums with polythene liners, or tin containers.
  • For retail distribution, condensed milk is typically packaged in cans using fillers.
  • Strict sanitary measures are crucial during the filling process to maintain product quality and prevent contamination.
  • Automatic filling machines are used for filling retail cans to ensure efficiency.

• Storage

  • Storage temperature plays a crucial role in preventing defects like sandiness, sugar separation, and viscosity changes.
  • Wide temperature variations during storage can increase the likelihood of sandiness.
  • Storage at very low temperatures, such as 0°C or below, can lead to sandiness and sugar separation.
  • Ideal storage temperature for condensed milk is around 10°C or slightly lower to maintain quality.

• Judging and Grading

  • A scorecard developed by the American Dairy Science Association is used for evaluating condensed milk based on factors like flavor, texture, color, fat content, milk solids, bacteria content, and sugar levels.

• Sampling

  • Randomly select a can of the product for examination.
  • Handle the can carefully to prevent agitation during transportation to the laboratory.
  • Examine the can in an upright position after cutting off more than three-fourths of the top.

Examination of Condensed Milk Quality

Appearance Evaluation

• Inspect the can for rust both on the exterior and interior after emptying.
• Check the product for consistent color and the absence of lumps, especially in condensed milk.

Viscosity Assessment

• Observe the viscosity level (high, normal, or low) while pouring the contents into a beaker.

Sediment Observation

• Check for the presence or absence of sediment at the container's bottom after emptying.

Flavor and Odor Analysis

• Identify any defects by tasting a small spoonful of condensed milk.

Chemical Analysis

• Take a sterile sample for testing fat content, total solids, bacteria, sugar, adulterants, and preservatives.

Requirements for High-Quality Condensed Milk

• High-quality condensed milk should possess a clean, pleasant aroma.
• It should have a distinct sweet taste and a smooth, uniform texture.
• The color should be uniformly light yellow for cow milk and light greenish-white for buffalo milk.

Condensed Milk Uses

• Utilization of condensed milk:
  • Deployed in remote areas and ships where access to fresh liquid milk is limited, owing to its extended shelf life and reduced volume, easing transportation.
  • Reconstituted for the creation of sweet milk beverages.
  • Added to tea or coffee.
  • Incorporated into ice cream formulations.
  • Included in the production of candies, confectionery, and various prepared foods.