Saving Milk

— Written By Debbie Stroud
en Español / em Português

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One of my favorite childhood movies was Heidi. There are many versions but I’ve only seen the one made in 1968. The scene when Klara gets her legs back is the best. Was her ability to walk again was due to the powers of fresh mountain air, her special friendship with Heidi, or was it the goat milk? After watching that movie as a child, I thought goat milk was magic. When I had the opportunity to try some as an adult, I loved it just as long as it didn’t come from nanny goats kept too close to billy goats; that milk tastes just like the billy goats smell… bad!

Milk holds a special place in the hearts and stomachs of many societies all over the world. This white fluid produced in the mammary glands of mammals is consumed by humans in a variety of forms: sheep, camel, goat, cow, yak, buffalo, horse, and reindeer.

While goat’s milk is the most popular milk consumed in the world, over 6 billion people in the world consume cow’s milk. India comes in as the top cow’s milk drinker in the world, consuming a whopping 77.7 million metric tons per year.

The United States has a population one-fourth of India’s but we consume more than a third of their total consumption, which comes out at 264 cups per person. We like milk. There was a time when we drank even more. Milk intake has been dropping in the U.S; in a 1978 survey 76% of adolescents reported drinking milk, by 2006 that percentage had dropped to less than 50% and it has continued to decline. In 1975, as a nation we consumed 247 pounds or 462 cups of milk per person; today’s consumption of 264 cups indicates a 57% decline.

In the past, lack of refrigeration led to the development of methods to preserve milk. Fermentation can convert milk into cheese, yogurt, and other similar foods. These types of foods can be made at home; yogurt is one of the quickest and easiest ways to ferment milk. Lactic acid bacteria are a group of microbes used to ferment dairy products. These microbes consume the sugars in the milk and produce acid, the acid preserves the milk by inhibiting food spoilage bacteria, this also changes the flavor and texture of the milk.

Milk is special because it is the perfect blend for baby animals to grow; but it is also the perfect environment for bacteria to grow. There are dozens of spoilage and foodborne illness-causing microbes associated with milk, this is why fresh milk is refrigerated, fermented, or pasteurized.

The process of pasteurization involves heating the milk to a high temperature (165ºF)  for a short amount of time (15 seconds). Pasteurized milk is still perishable, and needs to be refrigerated and used within 2-3 weeks. There are other forms of pasteurization that help milk last longer:

UHT or Ultra High-Temperature Pasteurization involves heating the milk to 280ºF for 1 – 2 seconds. This milk is still perishable and requires refrigeration, but has a 1 to 2-month shelf life, once it is opened it needs to be used like fresh milk. There are many varieties available in the refrigerated section of supermarkets.

UHT + Aseptic Packaging milk involves heating the milk to 280ºF for 2 seconds but with the added step of packaging it in a sterile (aseptic) carton, this extends the shelf life for 6 months or until you open it. You will find this type of milk in cartons or boxes on supermarket shelves because it requires no refrigeration.

Canned or evaporated milk is made by removing 60% of the water from fresh milk by evaporation. The milk is evaporated by simmering (not boiling) over heat until the desired amount of water is removed. Sweetened condensed milk is evaporated milk to which sugar has been added. The milk is then homogenized (an emulsification step so the fat does not separate), canned, and processed utilizing a retort. A retort is a pressure vessel used in food manufacturing to commercially sterilize the food after it has been placed into the container and hermetically (airtight) sealed. This extends the shelf life up to one year.

Dry (powdered) milk takes up little space and reconstitutes well. It is also preserved by evaporation. The process is fascinating – the milk is first evaporated to 50% milk solids. The concentrated milk is then sprayed onto a hot metal wall and the remaining water evaporates (almost instantly) leaving the milk powder to drop to the floor of the drying chamber. This extends the shelf life to 18 months.

Raw or unpasteurized milk can be contaminated with foodborne illness-causing microorganisms such as Brucella, Campylobacter, Cryptosporidium, E. coli, Listeria, and Salmonella and this is the shortlist, there are others. While it is possible to get foodborne illness from foods other than raw milk, this happens to be one of the riskier ways of getting sick. And just because you have consumed raw milk in the past and have not gotten ill, it does not make you immune to getting ill in the future. Those at greatest risk are the very young, older adults, pregnant women, and people with weakened immune systems. Foodborne illness outbreaks associated with consuming raw milk have occurred whether the animals were grain or grass feed, organic or non-organic. The most common source of reported foodborne illness associated with dairy products was due to the consumption of raw milk according to this 2013 study.

Pasteurized and dried milk can also cause foodborne illnesses if good manufacturing practices have not been followed and cross-contamination has occurred. Foodborne illnesses due to Salmonella have been associated with dried milk here in the US and in Europe. A comparison (1997) of the food safety of pasteurized and raw milk products was done and it was found that while approximately 1% of the US population drinks raw milk, it has caused 56% of the foodborne illness outbreaks associated with dairy.

Even though you can buy shelf-stable milk products in the store, home canning as a preservation method will result in a risky food.

Most fruits, vegetables, meat, fish, and poultry are can be safely canned at home. These items will require using either a boiling water or pressure canning processing method, depending entirely on the selected food. See the National Center for Home Food Preservation for more information.

Milk, as well as other dairy products, are not recommended for home canning because they are low acid, the fat they contain can insulate and protect spores from a foodborne illness-causing bacteria associated with home canning – Clostridium botulinum -from destruction during processing. When C. botulinum spores become vegetative, cells they can grow produce the deadly toxin that causes botulism poisoning. Canning dairy products themselves or adding them to other canned foods (such as when making soup) is not recommended.

When the proteins in milk are over-heated they drop out of the protein, fat, sugar, and water mixture, the milk separates; much like if you evenly mixed egg whites with water and then heated it, the whites would separate from the water and no amount of mixing would combine them again. The temperature necessary to heat and hold the milk at home for safe shelf-stability would cause this protein separation. Additionally, the sugars in the milk would cook, significantly altering color and taste (think about heating sugar to make caramel). The resulting turn out would be of very poor quality.

Other than adding a small amount of butter (margarine can also be used) to jams and/or jellies to reduce foaming no safe processing methods have ever been developed for home-canned milk or foods where milk or other dairy product have been added; even if you have seen recommendations online.

Is should also be noted that there are no tested recipes for at-home dehydrated milk since home equipment cannot dry milk fast enough to result in safe and high-quality food.

But as mentioned earlier, fermenting milk to make cheese and/or yogurt can be done safely at home and when a tested method is followed you can expect excellent quality.

Twenty years ago, the FAO (Food and Agriculture Organization) established World Milk Day, which is celebrated annually on June 1. They wanted to “recognize the importance of milk as a global food and celebrate the dairy sector. Dairy supports the livelihoods of 1 billion people and the focus this year (2020) was on the benefits of dairy in relation to health and nutrition, affordability, accessibility, and the commitment to feeding communities.

Here is one of my favorite greetings from World Milk Day – “Thankful for dairy farmers who make my favorite foods possible! Yogurt, coffee cream, cheese, ice cream!” I completely agree with this, even if I have to switch out the ice cream for frozen yogurt. Cheers to saving milk.