Milk and Milk Products Technology

PRESERVATION OF MILK

• Corrosive sublimate or mercuric chloride
  • Only a small amount is required, as this chemical is highly poisonous. A dye is used along with it to identify the sample as the one preserved with mercuric chloride. Since it is a health hazard, it is not used now a days.
• Formalin
  • Formaldehyde 40% by volume; 36% by weight. Add 0.1 ml to 30 ml of sample. Use this method for samples intended for test of fat. Since it is in liquid form, it is very convenient to handle.
  • Only objection against the use of formalin is that it causes a hardening of casein in milk, and hence not easily digested by sulfuric acid.
• Potassium dichromate
  • It is not a poison and so not dangerous to handle. This is most commonly used. It is cheap and safe.
  • It gives a bright yellow color to milk. Normally, 150 mg of potassium dichromate is used for 100 ml of milk.
• Bromo – 2-nitro propane-1-3-diol (Bronopol)
  • Use one tablet (containing 10 mg of actual ingredient) or 0.05 ml (containing 20% actual ingredient) per 50 ml sample.
  • Sample must be transported and stored at 0^ºC to 4.4^ºC. Life 5 days used in 1 RMA.