Milk

Milk is a white liquid food produced by mammals through their mammary glands for their offspring.  Humans first began to consume milk from their domesticated animals some 10,000 years ago.  While all mammals produce milk, it is the larger, domesticated herbivores and ruminants that have supplied humanity with milk.  These include cattle, goats, sheep, horses, buffalo, yaks, donkeys and camels.  Cow’s milk is the most popular for the large quantities it produces and its mild taste.  The term milk is also used to describe the white liquid extracted from various produce like soy, almond and coconut.

Pasteurization and Ultra-Pasteurization

Pasteurization is a process that kills harmful bacteria by heating milk to a specific temperature for a set period of time. First developed by Louis Pasteur in 1864, pasteurization is not intended to kill all micro-organisms, only to reduce the number of pathogens or harmful micro-organisms.  Pasteurization reduces the numbers of organisms responsible for such diseases as listeriosis, typhoid fever, tuberculosis, diphtheria, and brucellosis.  

The two main types of pasteurization are flash or HTST or (high-temperature, short-time) and UHT (Ultra-high temperature processing). In the HTST pasteurization, milk is heated to 161°F for 15 seconds.  Heating the milk removes 99.9% of the bacteria in the milk, which gives HTST milk an approximate shelf life of 16 – 21 days from the date it was packaged.  UHT pasteurization or “Ultra-Pasteurization” holds the milk at a temperature of 280°F for a minimum of two seconds and eliminates a larger percentage of bacteria than HTST pasteurization.  Ultra-pasturized products have a longer shelf life than HTST pasteurized products.  When coupled with sterile packaging, the ultra pasteurization process creates an extended shelf life but substantially alters the flavor of the milk.  Unopened, UHT milk (in aseptic packaging) can be stored up to 10 months at room temperature.  UHT processing of milk does give the milk a “cooked-milk” taste.

Homogenization

Raw milk will naturally separate, with the less-dense cream floating to to the top and the skim, non-fat milk settling to the bottom.  Homogenization is the process where the fat globules in whole milk are reduced in size and permanently dispersed throughout the liquid.

Raw Milk

Raw milk is milk that has not been pasteurized or homogenized.  Advocates claim there are health benefits to raw milk and that raw milk has a better flavor.  The FDA and medical communities warns of the dangers of unpasteurized milk.  The sale of raw milk and raw milk products is heavily regulated and banned in many states in the US and outright in Canada.  Raw milk and/or raw milk products however, are widely available throughout Europe and Asia.  According to the FDA, raw milk can carry strains of bacteria including salmonella, E. coli, and listeria which can lead to illnesses that cause vomiting, diarrhea and flu-like symptoms, which in severe cases can be life threatening.  Since more milk is consumed by children, the potential ill-health effects on a child’s developing immune system is a serious concern.  The agency also notes that, contrary to popular belief, pasteurization does not cause lactose intolerance or reduce milk’s nutritional value.  While raw milk does have the potential to cause illness, the risk associated with raw dairy products is low. In context, a 2003 risk assessment by the FDA documents a much higher risk for a food-borne illness in deli meats than raw milk. 

Milk Fat

When raw milk is processed commercially, the fat and skim portions are initially separated and then recombined to make various milk products.  Whole milk is 3.5% fat, 8.5% milk solids and 88% water.  Skim milk has most of its fat removed, with less than 0.5%.  Low-fat milk has between 0.5% and 2% milk fat.  

Whales and sea mammals have very high milk fat, 50% or more.  The milk is thick like toothpaste and is said to taste like a mixture of fish, liver, milk of magnesia, and castor oil.  A baby blue whale drinks over 50 gallons of its mother’s milk in a day. In its first several weeks of life, it gains 10 pounds an hour or a little over 200 pounds a day!

Condensed Milk and Dry Milk

In 1856,  Gail Borden patented his process for condensing milk.  With no refrigeration, milk spoiled easily and was expensive.  Borden developed a process of removing 60% of the water from milk and canning it.  40-45% sugar was added to inhibit bacterial growth.  In 1861, the Union Army purchased Borden’s condensed milk for use in field rations.  This first condensed milk product is known as Sweetened Condensed Milk.  In 1890, John Meyenberg (Pet Milk) developed a process for condensing milk without sugar, known as simply Evaporated Milk.  Milk that has most of the water removed is known as Dry Milk.  It includes whole milk, non-fat milk, and buttermilk.