Food Commodities 25

Milk

Milk is the white or ivory liquid produced by adult, female mammals and used to nurture their infant before they are able to digest other types of food. Some milk are used for human consumption either as is or processed into products such as cheese.

Non dairy milk is liquid resembling milk such as the liquid in a coconut or the juice or sap of various plants.

History of Milk

Milk has been a part of our nutrition since time immemorial. Rich in nutrients, milk in its various forms has a long, long history..

• Around 10 000 BC, the “agricultural revolution” occurred changing societies from nomadic tribes to those who settled in communities. With this came domesticated animals and the ingenuity for people to use by-products such as milk.
• In ancient Egypt, milk and other dairy products were reserved for royalty, priests and the very wealthy.
• By the 5th century AD, cows and sheep in Europe were prized for their milk.
• By the 14th century, cow’s milk became more popular than sheep’s milk.
• European dairy cows were brought to North America in the early 1600s.
• Louis Pasteur, a French microbiologist, conducted the first pasteurization tests in 1862. Pasteur is credited with revolutionizing the safety of milk and, in turn, the ability to store and distribute milk well beyond the farm. Commercial pasteurization machines were introduced in 1895.
• In 1884, the first milk bottle was invented in New York state.
• In the 1930s, milk cans were replaced with large on-farm storage tanks, and plastic coated paper milk cartons were invented, which allowed for wider distribution of fresh milk.

Milk Processing

Although some dairies have their own unique methods of milk production, most dairies in the United States follow the eight-step process seen below. Those eight steps are (in order):


Step 1 - Rearing 

Dairy cows typically spend their days eating, sleeping, and ruminating or chewing their cud. Cows in some dairy farms wander around and eat fresh grass (i.e. grazing). In other farms, they are fed grain, hay, or silage (conserved forage) and remain all day in close quarters known as confined animal feeding operations (CAFOs), some of which house thousands of animals.

Many large dairy farms utilize growth hormones and antibiotics during the rearing process to artificially increase a cow's milk production and to decrease the spread of infectious diseases among their cows.

Step 2 - Harvesting 

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Hand milking a cow, 2007

In the Past:

A cow is ready to be milked when her udder is full. The farmer has some flexibility when making a schedule of cow milking times. Usually, cows are milked in the early morning and again in the late afternoon. It is possible to milk a cow by hand. However, milking a whole herd of cows twice a day in this manner would take a great deal of time and energy. Before the invention of milking machines, people milked their dairy cows by hand by squeezing gently on the cow's teats using the thumb and forefinger. Some people continue to milk a little by hand today.

Machine milking a cow, 2007

Today:

Cows are normally milked at least twice a day. Milking time takes about five minutes per cow depending on the type of machine and the amount of milk the cow is producing. Most dairies have enough machines to milk more than 20 cows at one time. Milking machines mimic the action of a young calf by creating a pulsating vacuum around the teat, which causes the milk to be released from the udder.

Step 3 - Storing 

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Milk storage vat, 2007

Milk storage vats or silos are refrigerated and come in various shapes and sizes. Milk is usually stored on the farm at 39 degrees Fahrenheit, or colder, for no more than 48 hours. Vats and silos are agitated to make sure that the entire volume remains cold and that the milkfat does not separate from the milk. After milk has been collected, storage vats and stainless steel pipes are thoroughly cleaned before the farmer milks again.

 

Step 4 - Transportation

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Milk transportation truck, 2007

Milk is collected from the farm every 24 or 48 hours. The tankers that are used have special stainless steel bodies which are heavily insulated to keep the milk cold during transportation to the processing factory. Milk tanker drivers are accredited milk graders, qualified to evaluate the milk prior to collection. Tanker drivers grade and if necessary reject milk based on temperature, sight, and smell. A representative sample is collected from each farm pickup prior to being pumped onto the tanker. After collection, milk is transported to factory sites and stored in refrigerated silos before processing.

Step 5 - Lab Testing

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Milk testing in a laboratory, 2007 Source: AgSource Food and Environmental Division

Samples of milk are taken from farm vats prior to collection and from the bulk milk tanker upon arrival at the factory. Samples from the bulk milk tanker are tested for antibiotics and temperature before the milk enters the factory processing area. Farm milk samples are tested for milkfat, protein, bulk milk cell count and bacteria count. If milk does not meet quality standards it is rejected. Most farmers are paid on the quality and composition of their milk. 

Step 6 - Processing 

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Whole milk, once approved for use, is pumped into storage silos where it undergoes pasteurization, homogenization, separation and further processing.

Pasteurization machine, 2007

Pasteurization:

 

Involves heating every particle of milk to a specific temperature for a specified period of time and cooling it again without allowing recontamination.

Homogenization machine, 2007

Homogenization:

Involves pushing the raw milk through an atomizer to form tiny particles so that the fat is dispersed evenly throughout the milk, stopping the fat from floating to the top of the container.

Separation:

Involves spinning milk through a centrifuge to separate the cream from the milk. After separation, the cream and remaining milk are remixed to provide the desired fat content for the different types of milk being produced.

For "whole milk," the cream is reintroduced until the fat content reaches 3.25%. For "low fat milk," the fat content is 1%. For "skim milk" (sometimes called nonfat milk) the fat content is .05%. 

Machine for filtering and further processing, 2007

Further processing:

 

Includes micro-filtration, increasing the storage life by ultra high temperature (UHT) treatment, and mixing or culturing milk for flavored and yogurt products. 

Step 7 - Packaging 

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Machine filling and packaging milk, 2007

Now the milk is ready to be packaged for delivery to the stores. The milk travels through pipes to the automatic packaging machines that fills and seals the milk into paper cartons or plastic jugs. As the containers move through the assembly line, a date is printed on each of them to show how long the milk will stay fresh.

 

Step 8 - Selling

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Milk shelf in a store, 2007

After packaging, the milk is finally ready for the customers, and it is stored in a big, refrigerated room until it is delivered to stores to be sold.

Types of Milk

There’s a type of milk for every lifestyle. Whole milk contains at least 3.25% milk fat (M.F.), which is lighter than cream but has more body than lower fat milk. When a portion of the milk’s fat is removed, it becomes partly skimmed milk, such as 2% milk and 1% milk, depending on the quantity removed. Skim milk is virtually fat-free, with only about 0.1% fat.

Full cream

“Full cream milk has the highest percentage of fat in it -- around 3.8 percent on average,This has the creamiest taste due to the higher fat content.”

Whole milk is often called for in dessert recipes and adds just a touch of extra richness in coffee, soups and other savoury dishes. It can be used in any recipe calling for milk. It is available in cartons, bags, bottles or jugs.

If making good coffee is high on your priority list, full cream milk is most baristas' milk of choice for its ability to produce and hold silky frothiness.

Low fat

“This milk has slightly less fat in it -- around 1.3 percent to 1.4 percent, This milk often has skim milk powder added to it, which improves the taste to make it creamier and also boosts the protein and calcium content.”

“Low fat is better in terms of reducing how much saturated fat you’re having, so that’s really important when it comes to keeping cholesterol levels low and improving our heart health.

Low fat milk is also a good option for those watching their weight.

“You’re also shaving off a few extra kilojoules out of your diet so, for someone who is looking to lose weight, the low fat milk is a better option.

Skim milk

“This milk has the lowest amount of fat in it, with no more than 0.15 percent milk fat. “Typically, milk solids or milk powder are added to improve the taste of the milk.”

Many people may not enjoy the watery taste of skim milk, but it does have nutritional advantages.

“Nutritionally, the added solids or powder provides extra protein and calcium.

Skim and low fat milk do have a higher sugar content, but this is natural occurring sugar in dairy.

Partly skimmed milks are the most popular types of milk for everyday use. You can use both 1% and 2% interchangeably in recipes calling for milk. Both are available in cartons, bags, bottles or jugs.

“Some people are concerned that low fat products have added sugar in and that can appear to be the case -- when you’ve taken the fat out it looks like there’s more sugar left, but it’s just that naturally occurring sugar: the lactose.”Skim milk can be used in recipes calling for milk, though it may not provide enough creaminess in recipes using more than 2 cups (500 mL), or in those that specifically call for 1%, 2% or whole milk. It is available in cartons, bags and jugs.

Lactose-free milk

“This milk is suitable for people who are lactose intolerant. “The lactose in this milk has been removed, making it more easily digested for those with lactose intolerance.”

Avoiding dairy?

“The most important thing you need to ensure is that your new milk alternative is fortified with calcium, the nutritional panel and in the table where it says calcium, make sure there is at least 100mg for every 100ml of liquid.”

As the calcium is added in the form of calcium carbonate powder, Parker has one tip to ensure you're getting the most from the calcium.

“With the dairy-free milks the added calcium sinks to the bottom of the milk, so before you have it, shake the bottle up to make sure you’re getting the calcium in there.

Parker also advises to be wary of the sugar content.

“Be careful of dairy-free milks that have added sweeteners -- plenty of brands include sugar, honey and other sweeteners to improve the taste of the products. If this is a concern, opt for unsweetened varieties.

Rice and oat milk

Rice and oat milk are naturally sweet and are more palatable non-dairy milk options, but are not the best options in terms of nutrition.

“Probably the most questionable ones for me are the rice and oat milk. “There’s so much added sugar to it and they are so low in protein -- it’s essentially just sugary water with very little actual rice or oats.”

“Rice milk is good for people who have a lot of allergies because it’s the most hypoallergenic but, more generally, if you’re going to try dairy-free milk I would stick to the soy milk.”

Soy milk

“Soy milk is a good dairy-free option,. “It’s got a bit more of the good fats and has a higher protein content, so it’s going to help you to feel full which is what you want.”

Parker recommends looking for one with a high calcium content and, if you are concerned about sugar, opt for the unsweetened ones.

Almond milk

Almond milk is one of the most popular dairy-free milks. However, while it is high in vitamin E and low in fat, it's lower in protein than milk and, again, can be high in sugar.

Those who are environmentally conscious may also like to choose a different non-dairy milk. As Sarah Wilson discussed, it takes five litres to grow one almond and come with a large carbon footprint as almonds are usually imported to Australia.

The process of making almond milk also produces a lot of food waste, as the leftover pulp extracted from the almonds is often tossed away.

Flavoured milk

Although delicious, flavoured milk is not the recommended milk choice -- however, it’s better than some sugary drink options.

“Obviously I wouldn’t recommend going out and having chocolate milk, but if you are going to have a sweet drink, flavoured milk is probably going to be better than soft drink because at least it’s got some protein and vitamin A and B12.

Chocolate milk provides all the good nutrition of white milk and the same 16 nutrients. A deliciously satisfying drink, its ingredients are basically fresh milk, cocoa and sugar.

Store-bought chocolate milks are usually made with 1% milk and contain no more sugar than unsweetened apple juice.

Buttermilk

Buttermilk is fresh milk with an added bacterial culture (similar to yogurt) that gives it a tangy flavour and thick, rich texture. Buttermilk adds tenderness to baked goods, and a light, tangy flavour to soups and salads.

Raw Milk

The term “raw milk” refers to milk that has not been pasteurized. It is mandatory for all milk sold in Canada to be pasteurized to preserve the safety of the product.

Raw milk may contain bacteria that can cause serious illnesses, such as tuberculosis. Pasteurization destroys 100% of pathogenic bacteria, yeast and mould and 95% to 99% of other bacteria.

Some people believe that raw milk is healthier and easier to digest because of the “active” enzymes that it contains. These enzymes are thought to be deactivated by pasteurization, thereby making it more difficult for the body to digest pasteurized milk. However, just like pasteurization, the acid environment of the stomach also destroys certain enzymes. But rest assured: these enzymes are not required for digestion, and raw milk is not easier to digest than pasteurized milk.

You can find a number of raw milk cheeses on the market. Although manufactured according to strict guidelines, these cheeses may pose a risk particularly for pregnant women, seniors who suffer from chronic diseases, or people with weakened immune systems. Health Canada also states that soft or semi-soft raw milk cheeses, such as Brie, Camembert or Blue cheese, are more at risk of being contaminated with Listeria monocytogenes, a bacteria that can cause a serious illness called listeriosis.

Calcium Fortified Milk Beverage: Regular milk to which calcium is added, in addition to its natural calcium. While regular milk is a tasty and nutritious choice, calcium fortified milk beverages can help people meet their calcium requirements if their intake is inadequate.

Filtered Milk: Regular milk passed through fine filters to remove most microorganisms, making it seem creamier.

Lactose-Free Milk: Regular milk that has been processed to break down lactose (sugar) in milk to help people with lactose intolerance to easily digest milk.

Milk with DHA: Milk that comes from cows that are fed a conventional diet that has been enriched with DHA, a type of Omega-3 fat, from natural sources. This enriched diet allows cows to produce milk that is naturally higher in DHA (docosahexaenoic acid), which supports the normal development of the brain, eyes and nerves.

Omega-3 Milk Beverage: Regular milk with added ingredients, such as flax oil, which add Omega-3 polyunsaturated fatty acids.

Organic Milk: Milk from cows that are fed crops that are organically grown. Regular and organic milk are equally safe and nutritious.

Prebiotic Fibre Milk Beverage: Regular milk with prebiotic fibre added. Prebiotic fibre promotes and enhances the activity of beneficial bacteria that naturally inhabit our digestive tracts and help us to digest foods and keep our bodies healthy by controlling harmful bacteria and other microorganisms.

Probiotic Milk Beverage: Regular milk with added probiotic culture (bacteria that have an effect on health).

Evaporated Milk: About 60% of the water is evaporated from fresh skim, 2% or whole milk. The high temperature needed to sterilize the milk causes a browning reaction to occur, giving this milk a slightly darker colour. Evaporated milk is sealed into cans and is heat tolerant, making it excellent for baked goods and slow-cooker recipes.

Sweetened Condensed Milk: Made commercially by condensing milk to one third of its original volume and then adding sugar. Sweetened condensed milk is very thick and sweet and is available in cans. It is most often used in sweet baked goods; it is not interchangeable with other types of milk.

Powdered Milk (Skim or Whole Milk Powder): Partly evaporated milk is heated and dried instantly. Powdered milk is made from whole or skim milk and is available in bags and in bulk. There are instant and regular formulas. Once the package is opened, it should be used within one month.

UHT Milk: Sterilized milk that has been heat-treated at an ultra-high temperature (138 to 158°C). Once it has cooled down, the milk is poured into a sterilized package without air contact, usually a Tetra Pak type box. Unopened, UHT milk keeps for several months at room temperature. Once opened, it must be refrigerated and consumed within 3 days.

Different Types of Milk: Which One Is The Best? Full fat, low fat, skim, lactose-free, soy, rice, almond, oat -- with such an array of dairy and non-dairy milk products available, shopping for the right milk can be a confusing and difficult task.

The best milks

“As a general guide, opt for skim milk as this contains the least amount of saturated fat and also contains higher levels of calcium and protein, which is an extra nutritional bonus,” Parker said. “Try Pauls Physical No Fat with a whopping 174mg of calcium and 4.1 grams of protein per 100ml.”

For non-dairy milks, Parker's choice is soy milk due to it higher protein content.

“Try Vitasoy Calci-Plus which has 160mg calcium and 3.2 grams of protein per 100ml,” Parker said.

Milk Products





Sources
@ Webster's New World Dictionary of Culinary Arts by Steven Labensky, Gaye G.Ingram, Sarah R. Labensky
@ https://www.dairygoodness.ca/milk/the-history-of-milk
@ https://milk.procon.org/view.resource.php?resourceID=000658