Milk can be destined for direct consumption or processing into dairy products. Milk for direct consumption can be commercially classified as follows:
1) raw milk, which has not been heated higher than 40°C (104°F) nor subjected to a treatment with an equivalent effect. It can be bought on tap (from the farm) or packaged.
2) short-life milk, which has undergone heat treatment to ensure the destruction of all pathogenic microorganisms and part of the saprophytic microbial flora (usually to 72°C (162°F) for 15 seconds), followed by aseptic packaging.
- high-quality fresh pasteurized
- milk pasteurized at a high temperature (87-110 °C)
3) medium-life milk (UHT) which has undergone a high-temperature treatment (130-150°C (266-302°F) for anywhere between 20 seconds and a few fractions of a second) followed by aseptic packaging and with a minimum expiry date of 90 days from packaging. Normally stored at room temperature.
4) long-life milk (e.g. sterilized milk) which has undergone a double heat treatment, first for 130-150°C (266-302°F) for a few seconds, and then in a sealed container (120°C (248°F) for 20-30 minutes), with a minimum expiry date of 180 days from the packaging date.
Alongside these "traditional" milks are a number of "modified" milks:
- lactose-reduced milk: as many people are lactose-intolerant, the lactose content is reduced to around 2.5 percent and broken down into galactose and glucose, giving the milk a sweeter taste.
- milk enriched with plant fiber (inulin) and probiotics (Bifidobacterium and Lactobacillus acidophilus).
- milk fortified with the addition of vitamins, calcium, iron and other minerals.
- milk flavored with natural and artificial flavors like fruit, chocolate or vanilla.
- skimmed and semi-skimmed milk, in which the cream is removed using centrifugation. Skimmed milk must have a fat content below 0.5 percent and semi-skimmed milk must have a fat content between 1.8 and 2.5 percent.
- partly or wholly dehydrated milk, processed using sterilization or UHT treatments followed by aseptic packaging, dehydration and the addition of sugars.
Given all this, it is important to remember that not all milk is the same. It would be better to talk about milks in the plural, like wines, and to consider all the factors (breed, species, place of origin, diet, etc.) that make each milk unique. Defending differences instead of standardizing diversity is what we are fighting for.
Reference: "Le forme del latte", published by Slow Food editore