Milk and Milk Products Technology

USES / DEFECTS IN CONDENSED AND EVAPORATED MILKS

Uses of Condensed and Evaporated Milks

Condensed milk

For reconstitution into sweet milk drinks

• In tea or coffee
• In ice-cream preparation
• In candy and confectionery
• In prepared foods

Evaporated milks

For reconstitution into milk for feeding infantsand persons with weak stomach etc.,

• In ice-cream;
• In tea and coffee

Plain condensed milk : This is unsweetened condensed milk, made from whole milk, partly skim milk or entirely skim milk, and condensed to 2.5 to 4:1. It is used in ice cream factories and bakeries. The product is neither sterile nor preserved by sugar. Its keeping quality is similar to that of high quality, efficiently pasteurized milk.

Superheated condensed milk : This is plain condensed milk superheated byblowing live steam during condensing, to increase the viscosity.

Frozen condensed milk : This is plain condensed milk frozen to give ita longer storage life and is used in ice-cream factories mostly.

Defects in condensed and evaporated milks, their causes and prevention

Name of the defect	Causes	Prevention
I. Condensed milk a. Microbial defects
Mould buttons	Contamination with and growth of Aspergillus sps. Storage at high temperatures Presence of oxygen in the head space of the package	Avoiding contamination with Aspergillus sps. Storage at low temperature (10-15ºC ) or below Vacuum or gas packaging
Bacterial thickening	Contamination with species which produce rennin like enzyme Storage at high temperature 3. Low sugar ratio	Avoiding contamination with species which produce a rennin like enzyme Storage at low temperature (10-15ºC ) or below Optimum sugar ratio
Bloats (microbial)	Contamination with and growth of Torula lactis condensi (yeast) 2. Storage at high temperature	Avoid contamination with and growth of Torula lactis condensi (yeast) Avoid storage at high Temperature
b. Non-Microbial
Sandiness due to lactose	Incorrect cooling and Crystallization Excessively low temperature of storage	Correct cooling and Crystallization Correct temperature of storage
Sandiness due to sucrose	1. Excessive sugar ratio 2 Excessively low temperature of storage	Optimal cooling and Crystallization Optimal temperature of storage
Age-thickening (physico-chemical)	Excessive forewarming temperature and/or homogenization pressure Adding sucrose before forewarming Storage at high temperature Low sugar ratio	Optimum forewarming temperature and/or homogenization pressures Adding sucrose only at the end of condensing Storage at low temperature (10 ºC ) Optimal sugar ratio
II. Evaporated milk
Cooked flavour	High heat treatment during sterilization by the conventional method of heating.	Ultra-high-temperature sterilization and aseptic packaging reduces-but may introduce the problem of more spoilage and cooked flavour
Feathering in coffee	Excessively high viscosity	Optimum viscosity