Modifying the Original Milk Composition
Market milk may be sold raw or heat treated, normalized or not in its fat content, almost always prepacked at the dairy. Raw milk-vending machines are an exception: Consumers may fill their own bottles, either taken from home or bought locally. The sanitary risks associated with raw milk consumption are still considered to be so important that in some countries raw milk must be compulsorily boiled at home before consumption.
Heat-treated market milk may be classified according to the treatment intensity:
- • Pasteurized milk (short durability, to be kept in the fridge)
- • HT pasteurized milk (extended shelf life (ESL), medium durability, to be kept in the fridge)
- • UHT milk (long durability, ambient)
- • Sterilized milk (extra long durability, ambient)
The second category includes not only products heat-treated with high tempera- ture/short time (HTST) at temperatures over 80°C (peroxidase negative), but also high temperature/very short time (HTVST) steam infusion (ESL milk) and pasteurized microfiltered milk.
Cream, as a fat-enriched milk, follows the same classification, but, due to the well- known fat protective effect on microorganisms, it must be submitted to heavier heat treatments than milk in terms of time and temperature.
Market milk may be fortified for nutritional or dietetic purposes. It may, for instance, be enriched with proteins, vitamins, minerals (e.g., calcium and vitamin D3), LC-PUFA omega3, soluble prebiotic fibers, or live probiotics.
Milk can be delactosed by enzymatic hydrolysis to prevent symptoms due to lactose malabsorption or be added with ingredients and eventually additives to become nonfer- mented milk-based drinks.
In countries where it is legally admitted, market milk may be prepared from milk powder (reconstituted milk) or from milk products (recombined milk).