Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food.


1   History

The Greeks and Romans despised the Gauls and Celts for drinking milk and consuming butter. However, cheese was acceptable. Mediterranean people had little need for butter. They already had olive oil, which is less prone to spoilage, heats to higher temperatures before burnings, and which was regarded as more healthy. Even today, the Mediterranean consumes little butter. In contrast, in the north, milk spoiled less quickly. [3]

Additionally, in Rome, because milk would spoil, fresh milk was only consumed by farmers and peasants. This led to fresh milk being regarded as a food of low status. [3]

The Dutch may be credited as raising the social status of milk and butter.

An ample supply of cheese and butter was the right of every Dutchman. They believed that dairy food was an essential part of a good diet, and artists from the celebrated Dutch school of still-life painting often included cheeses in their compositions. The Dutch made many cheeses and had an effective distribution system, with numerous urban centers featuring cheese markets. [3]

In the 13th and 14th centuries, the Dutch became skilled at reclaiming land from the sea by building dykes and creating polders, drained patches of reclaimed seabed. This led to dramatic improvements in cattle breeding and land maintenance. Farmers began having tremendous success crossbreeding livestock to develop cows that produced more milk—between the mid-16th and mid-17th centuries, the value of a Dutch cow quadrupled. The Dutch were starting to understand what best to feed cattle, and how best to cultivate pastureland. Soon, their cows were producing more than twice the yield of cows in neighboring countries. [3]

Though at first unnoticed, a huge shift occurred in the European perception of the Dutch. Their country, which had broken off from Spanish rule in the 1590s, was rapidly changing from a former lowly possession of the Holy Roman Empire to an independent republic displaying a genius in art, science, and engineering. Seemingly overnight, the Netherlands became a global trading empire and leading maritime and economic power of the world. Suddenly, the cheese heads were considered brilliant. [3]

All over Europe there were discussions and writings about what made the Dutch such geniuses. And those having these discussions often freely admitted that they had once thought of the Dutch as idiots who just drank milk and ate cheese. The Europeans also started recognizing that there was genius in Dutch dairy farms—in their better pastures, better cows, and ability to farm below-sea-level land. Dutch dairying, too, was now considered brilliant. [3]

After the cheeseheads proved themselves geniuses—and established a widely emulated, global empire—the main bastion of anti-dairy sentiment was East Asia. Japanese Buddhists avoided dairy products and looked down on Westerners, who they thought consumed too much dairy. [3]

Similar sentiments existed in China, where the consumption of dairy has been so rare that historically, many have assumed that the Chinese as a race were lactose-intolerant. This contrasted with their neighbors, the Mongols, who drank mare milk and traveled with dried cheese curds. [3]

2   Substance

Liquid bovine milk contains approximately 87% water, 3.5% fat, 4.9% carbohydrates, 3.9% protein, and 0.7% ash such as various vitamins and minerals. [4] Milk composition varies widely depending on the species and their immediate environment. Milk from cow, goat, sheep, and other species have unique compositions and differentiate further within various breeds. For example, Guernsey and Jersey cattle are well-known for producing milk with a rich flavor due to its higher fat content, while Holstein-Friesian cattle produce larger quantities at a lower fat content. [4] Other factors, including feeding regimen, dietary fat, intervals between milkings, and season, contribute to the composition of milk. [4]

Milk consists of water, lactose, fat, minerals, vitamins, and bacteria (including lactobacillus, which is needed to make makes yogurt, chees, sauerkraut, pickles, beer, wine, cider, kimchi, chocolate). [2]

Lactobacillus consumes lactose and produces lactic acid. As the milkbecome more acidic, it begins to curdle or coagulate. This is many dairy product are made include cheese. (The sour smell is from the lactic acid.) When you milk starts to sour, it basically is turning itself into cheese. [2]

This process takes time because milk is pasturized, which kills bacteria by heating it up. The sell by date is usually 14 days after pasteurization, a date by the process of milk guarantees it to be fresh. [2]

Milk must be kept cooled to prevent bacteria from becoming more active. [2]

2.1   Carbohydrates

Of all the carbohydrates in milk, lactose predominates in bovine milk, making up approximately 98% of all carbohydrates. [4] Other sugars exist in trace amounts. [4]

Lactose is a disaccharaide of glucose and galactose. [4]

Lactose must be broken down by lactase into its constituent monosaccharacides for intestinal absorption. [4]

Lactose provides most of the calories in milk. [4]

It is estimated that 70% of the world's popular suffers from lactase deficiency, which leads to an inability to break down lactose causing symptoms such as osmotic diarrhea. [4]

  • Lactose is a solution (homogeneously mixed in) in milk
  • Less soluable than sucrose, so less sweet (16% as sweet)
  • Increasing temperature of milk increases solubility of lactose and perceived sweetness

2.2   Fat

Milk fat contains many different types of `fatty acids`_. The majority of these fatty acids are short-chain fatty acids and C_14, C_16, C_18, and C_18:1 fatty acids. Certain fatty acids are important for the formation of dairy products such as butter. [4] In liquid milk, these fatty acids form milk fat globules (MFG) with a diameter generally between 1 and 10 micrometers. [4] Fat-soluble vitamins, such as vitamins A, D, E, and K, are found in the lipid components of milk. [4]

When milk sits, the larger MFGs rise, initiating a process known as "creaming". As these fat globules rise, they create the distinct "cream line" at the surface and expose the lipids to degradative reactions that shorten shelf life. Creaming can be prevented by homogenizing the milk. [4]

2.3   Protein

Proteins in milk case be classified into two main groups: caseins and whey proteins. Caseins make up approximately 80% of total milk protein and whey protein makes up the other 20%. [4]

Caseins can be divided into 5 main groups: alpha s1, alpha s2, beta, gamma, and kappa. These subunits bound by calcium phosphate bridges form aggregates with other subunits forming micelles_. It is these casein micelles that give milk its characteristic white color. [4]

Whe proteins includ beta-lactoglobulin, alpha-lactalbumin, blood serum albumin, immuno-globulins, and other proteins. These proteins are also called "serum proteins" because they remain if fat and casein are removed from the milk. [4] Isolated whey products are major by-products formed from cheese production and often are added to other foods such as breads. [4]

2.4   Minerals

Bovine milk contains various ions, minerals, and vitamins. The most obvious is calcium, but potassium_, sodium, chloride_, phosphate_, and magnesium_ also appear in milk. Milk contains the vitamins A, B, C, D, E, and K. [4]

Milk can also be fortified, particularly in the case of skimmed milk, which must be replenished with vitamins A and D. [4]

3   Operations

3.2   Foaming / Steaming

Milk foam is created using a milk jug or a steam wand.

Foam stability decreases reaching from 0% to 5%, then strictly increases

Increases in fat content also cause a decrease in foam volume:

  • Skim milk gives most foam and is stable
  • Whole milk has more taste, but is harder to foam

Protein enables milk to be foamed.

All milk, regardless of fat content, creates the greatest volume of foam at cooler temperatures.

  • Steam spout placed into jug of milk
    • Purpose is to aerate milk
      • Creates waves which trap air, similar to whisking
  • Properly prepared milk is always foamed
  • Incorporating air into the milk improves and sweetens the taste

Both proteins are stable up to 140F. After that, become susceptible to denaturation (won't foam). Milk cannot be foamed twice== need new milk.

4   Consumption

Milk is served with coffee.

Fat adds flavor. The sweetness of milk come from lactose, a milk sugar.

4.1   Products

A dairy product is food produced from milk.

  • Cheese
  • Half & Half
    • Little protein== just fat
    • $2 / qt at Wawa
  • Light Cream
    • Lots of fat
    • $2 / pt at Wawa
  • Cream
  • Whipped cream
  • Gelato

4.1.1   Ice cream

Partial melting of ice cream will cause a big change in texture - so I'd advise you to do everything you can to keep the ice cream completely frozen the whole time.

The texture of ice cream comes form air being mixed in during the freezing process. When it melts slightly, the air escapes, and when the remaining liquid refreezes you get flavored ice, not ice cream.

4.1.2   Whey

Whey is the liquid remaining after milk has been curdled and strained. It is a byproduct of the manufacture of cheese.

Whey is an abundant source of branched-chain amino acids (BCAAs), which are used to stimulate protein synthesis.

Whey protein is superior to all other protein powders. It digests the fastest, has the best amino acid profile, and is the most economical.

Whey comes in multiple forms.

Whey Protein Concentrate
Has a protein content of around 80%.
Whey Protein Isolate

Has a protein content of around 90% because whey protein isolate undergoes a process called Cross-Flow Micro-filtration. This separates the protein from fat, cholesterol and lactose meaning a purer protein as the end product.

Although whey protein concentrate is already considered low in lactose, whey protein isolate is considered even lower because of the additional manufacturing processes. Whey protein isolate is therefore often recommended for athletes who suffer from lactose intolerance. But it is typically more expensive due to the additional manufacturing process it undergoes.

TrueNutrition sells among the cheapest and also highest quality protein powders (you can use the code LMR104 when checking out for an extra 5-10% off). Optimum Nutrition is another well-recommended brand (don't get too crazy with the flavors, my favorite is the standard Double Rich Chocolate). There are a number of different protein powder options available with a myriad of prices: Hydrolized whey, one of the more expensive options, goes through a denaturing process, giving it a sweeter taste and helping the power dissolve more easily in water or milk. Whey isolate has additional branched chain amino acids (BCAAs) in it, eliminating the need to buy a separate, more expensive, BCAA supplement. If you're on a budget, though, the cheapest option generally does the trick.

LabDoor ranks whey protein from Myprotein among the best.

5   Health

Milk contains a fair amount of sugar but is otherwise nutritionally complete.

Milk proteins are a tremendous source of value to human health. The combination of caseins and whey proteins provide all eight essential amino acids that the body cannot produce on its own. [4]

Drinking a gallon of whole milk a day ("GOMAD") is an effective way to gain weight. It's cheap (120g of protein, 2500 calories for $4), natural, and easier to digest than solid food. [1] The proteins are also animals proteins (20% whey and 80% casein_). [1] Saturated fat also increases testosterone levels, which improves muscle gain. [1]

6   Spoilage

The component of milk provide ideal conditions for microrganisms to degenerate and spoil milk.

The standard for spoiled milk depends on the culture. For example, moldy cheeses and yogurts may be avoided by one person yet sough after by another.

The most common cause of spoilage is the proliferation of microorganisms such as bacteria and fungi which metabolize milk components to form unwanted byproducts. Milk spoilage is characteristic for its rapid onset, which is a direct result of exponential microbial growth. [4]

By-product of lactose form from bacteria include various acids and gases which create "sour" and "gassy" defects. Lactic acid bacteria (LAB) can metabolize lactose for growth. As these bacteria proliferate, they product `lactic acid`_ as a by-product, thus decreasing pH from the industry standard of 6.6 to 4.5. When milk reaches pH levels below 4.5, the acidic condition can lead to curdling. [4]

While raw milk is sterile when first released from mammary glands, contact with the cow's udder, teats, and external environments allow for bacteria to contaminate the milk. [4]

With the use of refrigeration to store raw milk in most developed countries, psychotrophic bacteria have become the leading cause of spoilage. This is largely due to their ubiquitous distribution in nature and their ability to grow at low, cold temperatures. Psychotrophs are commonly found in soil, water, as well as air. [4]

Milk in the US does not spoil for three weeks. However, in many other parts of the world, fresh milk has much shorter shelf life. Milk is highly perishable.

In places like Uganda, milk typically lasts just one day. The cow gets milked, and farmers, most of whom have just a few cows, rush to get the milk directly to the consumer. If it doesn't arrive in time, it will probably go to waste.

Why? Because three-quarters of Ugandan dairy producers don't have a way to pasteurize the milk or keep it cool. The same goes for other African countries, such as Ethiopia and Zambia.

But short shelf life isn't just a problem in Africa. Fresh milk in Brazil lasts only three to eight days — depending on the availability of refrigeration.

Unlike Uganda, fresh milk in Brazil typically undergoes pasteurization, a heat process that kills off bacteria to make milk last longer. (Editor's note: As several commenters have noted, ultra-pasteurized milk in unrefrigerated cartons is another product available in Brazil and other countries. Its shelf life can be several months.)

But after it leaves the farm, it is often exposed to heat on its way to the consumer, which cuts into the shelf life. So what does the U.S. (and other developed nations) have that these countries don't? A complex system to keep milk cold, says William Kisaalita, an engineer at the University of Georgia. It's called the cold chain, and it's a series of refrigerated tanks, trucks and storage units that milk — and other foods — travel through from farmer to distributor to consumer.

Dairy is one of the top three foods wasted in the U.S., and some 17 billion pounds of milk, or 32 percent of the total supply, is lost a year, according to 2010 U.S. Department of Agriculture data.

7   Production

Feed and water a dairy cow needs in 2018 to produce one gallon of milk: 4 gallons of water, 10 lbs of feed. In 1945: 12 gallons of water, 50 lbs of feed.

2/3 due to better genetics, and 1/3 due to better management. The nutritional value of milk is the same.

8   Further reading

9   References

[1](1, 2, 3) Mhedi. Feb 5, 2015. GOMAD: How to Gain 25lbs in 25 Days with Squats & Milk
[2](1, 2, 3, 4) Dino Giacomazzi. Jan 27, 2011. Why does my milk go bad before the expiration date?
[3](1, 2, 3, 4, 5, 6, 7, 8) Mark Kurlansky. May 29, 2018. Remembering When Only Barbarians Drank Milk.
[4](1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24) Michael Lu, Nam Sun Wang. Spoilage of Milk and Dairy Product. The Microbiological Quality of Food.