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Pasteurization of Summerhill Goat Milk

All About Pasteurization

At Summerhill Dairy, we seek to be as transparent as possible with customers about our operations and processes. So when someone last week asked us about our pasteurization process, we felt like a detailed explanation was warranted.

What is Pasteurization?

First, let’s define our terms. Pasteurization is a process by which foods are heated to a specified temperature for long enough to kill or deactivate harmful bacteria. Pasteurization does not significantly alter the nutritional composition or profile of goat milk (or any other milk), and nutrient losses from any pasteurization process are negligible. 

When milk is not pasteurized, it can contain harmful pathogens (such as Brucella, Campylobacter, Cryptosporidium, E. coli, Listeria, and Salmonella) — germs that can lead to sickness, hospitalization, or death. Between 2007 and 2012, the CDC linked dozens of foodborne outbreaks to non-pasteurized milk. Meanwhile, the FDA uses evidence from such outbreaks and numerous scientific studies to “clearly demonstrate the risk associated with drinking raw milk.” Not surprisingly, federal law mandates all milk distributed across state lines must be pasteurized.

At Summerhill, food quality and safety have always been our highest priority. Everyone should be able to enjoy the benefits of goat milk without having to worry about their health. We have always pasteurized our goat milk — and will continue to do so. Because we believe it’s simply the right thing to do.

Different kinds of pasteurization

All pasteurization involves some amount of heat applied for a certain length of time — followed by rapid cooling. But there are a few variations on this basic idea, and different methods of pasteurization can affect characteristics such as taste or shelf life. With that in mind, let’s take a deeper dive into the three main methods used for the commercial pasteurization of goat milk.

Vat Pasteurization / Low Temperature Long Time (LTLT)

Prior to moving our facility in Hanford, California, all of our goat milk was vat pasteurized — so we are quite familiar with this process. Generally considered the “original” way to pasteurize milk, vat pasteurization heats milk in a large tank to at least 145ºF for at least 30 minutes. This process generally requires a large boiler and large volumes of water to sustain a constant temperature. Vat Pasteurized goat milk can be cultured (turned into butter, cheese, yogurt, etc.), and the shelf life (when refrigerated) of vat pasteurized goat milk is roughly two to three weeks.

In recent years, vat pasteurization has become somewhat trendy. Many smaller milk processors have begun to use the term to make their products seem more “farm-fresh.” Some advocates of the LTLT method claim that the slightly lower temperatures used in vat pasteurization better preserve a milk’s “natural flavor.” However, science has been used to show that the significantly longer holding times lead to alterations in both protein structure and taste.

At Summerhill, we used vat pasteurization on our products for several years, and we don’t think it leads to a better or worse goat milk. In our opinion, vat pasteurized goat milk tastes almost exactly like the flash pasteurized milk we produce now, and we don’t think it was any easier (or any more difficult) to digest.

Flash Pasteurization / High Temperature Short Time (HTST)

Today, Summerhill Goat Dairy utilizes a process called flash pasteurization. The goat milk is heated to 161ºF for 15 seconds. In our opinion, flash pasteurized goat milk is nearly identical to vat pasteurized goat milk in most ways. Shelf life is comparable. Both forms of pasteurization allow goat milk to be cultured (so you can use it to make cheese, yogurt, and kefir.) And the taste is nearly identical. When we first moved to flash pasteurizing in 2010, we couldn’t tell the difference — and we drink goat milk every single day — and not a single customer told us that they noticed a change in taste or quality.

With that said, flash pasteurization does have a few important advantages over vat pasteurization — which is why we chose it when moving to our new creamery. Flash pasteurization takes only a fraction of the time of vat pasteurization (15 seconds vs. 30 minutes), so flash pasteurization uses significantly less energy. For a goat milk dairy and creamery that is powered by solar energy, energy consumption was a major consideration. We pride ourselves on running a lean, efficient operation, and flash pasteurization best aligned with our values.  

Flash pasteurization also uses much less water, which gives it another advantage over vat pasteurization. Summerhill is located in the heart of the Central San Joaquin Valley — arguably the richest agricultural region in the world — and taking water away from farmers that could be growing food doesn’t feel like the right thing to do when a better, more water-wise option existed. We seek to be good stewards of the resources entrusted to us, and flash pasteurization seems like the best choice for us.

Ultra Pasteurization

Lastly, we need to spend a few minutes looking at ultra pasteurization, another process used to make milk safe and shelf-stable. Ultra-pasteurized milk is heated to at least 280˚F for a minimum of two seconds. The process is fast and allows for an incredibly long shelf life (up to 45 days!)

But ultra pasteurization has some drawbacks that make the process not an option for us at this time. We simply can’t bring ourselves to intentionally damage the flavor of Summerhill Goat Milk that our customers have come to love.  And ultra pasteurization effectively destroys the enzymes in the milk that allow it to be cultured into other products, such as cheese, yogurt, and kefir. All of our customers who purchase Summerhill Goat Milk for that purpose would be unable to make their delicious homemade cultured products.  


We flash pasteurize our milk because we think this option makes the most sense for us. Summerhill Goat Milk tastes great, is safe to drink, and is comparatively easy on the environment. But we understand that other people might prioritize certain characteristics or attributes of goat milk differently than we do. This article wasn’t written to prove anyone right or wrong. It is simply an explanation of why we do things the way we do — and why we stand behind our products and processes.

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