Veterinary Medicine: Milk Hygiene and Ice Cream

Ice Cream Composition

• Ice cream is a frozen product made from milk and milk products, sweeteners, stabilizers, emulsifiers, flavorings, and coloring matters.
• Nutritive value of ice cream: milk fat supplies energy, essential fatty acids, and fat-soluble vitamins; carbohydrates serve as an energy source; rich in minerals (e.g., calcium) and vitamins (e.g., A, D, E, K).

Ingredients of Ice Cream

• Basic ingredients:
  • Milk fat (10%-16%): provides creaminess and richness, contributes to melting characteristics.
  • Milk Solids Not Fat (SNF) (20% total, 9-12% SNF): plays an important role in body and texture, and serves as a source of lactose, caseins, whey proteins, minerals, and vitamins.
• Additional ingredients:
  • Sweeteners (10%-14%): provide sweetness, lower freezing point, and help with scoopability.
  • Stabilizers (0%-0.25%): add viscosity, control ice crystallization, and provide smooth texture.
  • Emulsifiers (0%-0.25%): help mix liquids, distribute fat evenly, and create a smooth product.
  • Flavorings and coloring materials (optional): add flavor and color to ice cream.

Large Scale Manufacture of Ice Cream

• Mix manufacture:
  • Mix calculations: estimate and weigh ingredients based on desired components.
  • Blending: ensure complete mixing of liquid and dry ingredients.
• Pasteurization: heat mix to 68°C for 30 minutes or 80°C for 25 seconds to decrease milk fat globule size and contribute to a smoother, creamier ice cream.
• Homogenization: decrease milk fat globule size, improve emulsion, and create a smoother texture.
• Cooling and aging: cool mix rapidly to 4°C, then age for at least 4 hours or overnight to allow milk fat to partially crystallize and improve whipping properties.
• Freezing and air incorporation: freeze mix at -5°C or less, incorporating air to create overrun, which can reach 100%.
• Adding fruits, nuts, or chocolate: add mix-ins after freezing to prevent interference with smooth flow and damage to pieces.
• Packaging: package ice cream in a suitable container, properly sealed.
• Hardening: freeze packaged ice cream to below -18°C, creating small ice crystals and a smoother texture.

Defects in Ice Cream

• Color defects:
  • Non-uniform color
  • Too high or too pale color
• Flavor defects:
  • Off-flavors due to cooked ingredients, excessive sweetener, lack of flavor, unnatural flavor, or bacterial growth
• Body and texture defects:
  • Crumbly, brittle, friable body due to low solids, low stabilizer, excessive overrun, or improper homogenization
  • Gummy, pasty, sticky, elastic body due to too low overrun, too much stabilizer, or poor stabilizer
  • Heavy, doughy, pudding-like body due to low overrun, high solids, or excessive stabilizer
  • Shrunken ice cream due to temperature fluctuations, excessive overrun, rough transportation, or low solids
  • Weak, watery body due to low solids, low stabilizer, or high overrun
• Melting quality defects:
  • Delayed melting due to excessive stabilizer, emulsifier, high fat content, or freezing to too low a temperature
  • Curdy meltdown due to high acid mix and coagulation of milk proteins
  • Watery, low melting resistance due to low solids, low stabilizer, or high overrun
• Package defects:
  • Soiled, bulging, improperly sealed, rusty, or damaged containers