Raw milk is rich in nutrients—the primary reason why is it one of the highly perishable food items. To give you an idea, raw milk in the refrigerator may only last for only several days (7 to 10 days). Without subjecting it to high heat, raw milk may contain harmful microorganisms, particularly pathogenic bacteria. Pathogens such as Salmonella, E. Coli, and Campylobacter are commonly found in raw milk. Drinking contaminated milk may cause serious illness or even death.

For this reason, raw milk is tightly regulated anywhere in the world. In the United Kingdom (UK), consumers can only purchase raw milk directly from registered milk farms, direct online sales, and farmers at registered farmers’ markets. Scotland has completely banned the sale of raw milk. In the United States, the Food and Drug Administration (FDA) has prohibited the interstate sale of raw milk since 1987. Today, raw milk comes from highly hygienic farms where infections are rare, due in large part of the laws that exist.

Raw milk is meant for immediate consumption. But what about milk unrefrigerated on the shelf and in the refrigerator at the supermarket?

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Heat treatment makes it possible for milk to be stored this way. Heat destroys the pathogenic bacteria that may be present in the milk, extending its shelf life. This more shelf life stable form of milk is what the most of us consume. But if you frequent your local supermarket for your dairy supplies, you might have noticed that milk usually comes in two forms according to heat treatment: UHT (Ultra High Temperature) milk and pasteurized milk. But what exactly are the differences between UHT and pasteurized milk?

Let’s find out.

UHT vs Pasteurized milk

Basically, both forms of milk have been heat treated in a process called pasteurization. By definition, pasteurization is the partial sterilization of a product In order for it to be safe for human consumption. This process was named after the French scientist, Louis Pasteur, after he discovered that microorganisms are responsible for the souring of alcohol. By heating the beverage and then quickly cooling it destroy the bacteria and thus extending its shelf life. Today, many food items go through pasteurization including syrups, juices, eggs, beer, and milk.

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In dairy milks, there are basically three levels of processing—raw milk, pasteurized, and ultra-heat treated (UHT) milk.

Pasteurized milk is milk treated to a high temperature of 162°F (72°C) for 15 seconds. This heat is sufficient to eliminate the pathogens that may be present in the milk. While the duration of the treatment makes it possible to preserve the flavor, it starts to decline after several days. Under proper refrigeration, pasteurized milk can last for up to 3 weeks.

However, it is advisable to consume pasteurized milk before its expiration date written on the label. In the US, the storage temperature for raw and pasteurized milk must be maintained to 45°F (7°C) or lower.

UHT milk, on the other hand, is more shelf-life stable than pasteurized milk. UHT-treated milk is milk that has undergone a high temperature of 284°F (140°C) for 4 seconds. This destroys virtually all the microbes, spoilage enzymes, and unfortunately, the good bacteria (probiotics). And since UHT uses a temperature twice as high as that of pasteurized milk, UHT does not necessarily have to be heated for quite as long. UHT milk sealed in an aseptic packaging can last for up to 6 months or longer even if stored without refrigeration. This answers why milk on the supermarket shelf does not easily go bad.

Are these two better than raw milk?

It depends. Quality-wise, nothing beats raw milk. It it full of flavor, richer, and more creamy. Because it does not undergo any heat treatment, it retains its components, especially proteins, making it ideal for cheese processing. Studies have also revealed that raw milk contains more bioavailable nutrients, probiotics, as well as beneficial enzymes.

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Obviously, the only downside of raw milk is its perishability. Raw milk is highly perishable—It lasts only 7 to 10 days. Plus, it starts losing flavor after one day. So if you are going for raw milk, make sure it is consumed immediately.

While heat treatment allows milk to be stored safely for longer period, it is worth noting that heat alters the quality of milk, especially the nutrients and taste. This is especially true for UHT milk. The temperature it uses denatures the active protein, which degrades further during storage. Moreover, the calcium becomes insoluble. This means our body will have a harder time absorbing the bone-strengthening mineral after heat treatment.

Another disadvantage of UHT is milk is its altered taste. The ultra-high temperature affects the sugars in the milk, prompting caramelization to occur, reducing the creaminess, and giving the milk a burnt taste. When talking about convenience, UHT milk is a clear choice as it can reach distant places without spoiling. (UHT milk, by the way, is the most dominant form of milk in Asia.)

But if you have a fridge at home and are wary of the safety of raw milk, it is better to go for pasteurized milk. Its shelf life is long enough, and its quality is comparable to that of fresh raw milk.

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