Pasteurization: What's the Big Deal?

Fortune favors the prepared mind. ~Louis Pasteur

Watching Rachel Alexander win the Preakness was inspirational. No doubt horse racing has its animal abuse issues, but thoroughbreds are still breathtaking athletes. 

I was fortunate to spend a little time traveling in Mongolia, where horses are still the major mode of transportation on the steppe. Horses are revered there, and I shared some airaq (fermented mare's milk) with my hosts. (Fermentation adds good microbes to food, but today's topic is about eliminating microbes with pasteurization). Dairy is a major part of the nomadic summer diet, and I would help the family milk some of the animals. Then we would haul the milk back in buckets and heat it on the stove for tea. I never noticed anyone drinking raw milk. I didn't think about it then, but I think we were home-pasteurizing the milk.

Milk is weird - humans are the only animals that drink milk from other animals. However, it is a good source of calcium, so there are a lot of milk drinkers. The vast majority of milk in the U.S. is pasteurized, which has become a subject of debate. In addition to milk, many other beverages and foods are pasteurized - orange juice, beer, wine, almonds, etc.

So what is pasteurization and why is it an issue? 

Pasteurization kills dangerous microorganisms to sterilize food and drink. To pasteurize, you heat the substance below boiling for several minutes. This now seemingly simple science was discovered by Louis Pasteur, the father of microbiology, in the 1800's.

Pasteurizing allows food to be shipped further distances, and increases its shelf life. Not many of us live next to a farm, and shipping and handling allows microorganisms to enter and grow in unpasteurized food. Pasteurization has saved millions of lives - that is why raw milk is illegal in many states.

So why is there an anti-pasteurization movement? Pasteurization doesn't discriminate in its microbe killing - it kills good microbes in addition to pathogens. People argue that if food is fresh and handled well, the risk of contamination, illness and death is insignificant. Pasteurizing food is processing food, and killing off beneficial microbes and enzymes significantly reduces the nutritional value.

This may be true, but not all of us have the physical or financial access to clean unpasteurized foods. So we just need to know what we're buying. There are many different levels of pasteurization. Using milk as an example:

• Vat/batch pasteurization (low and slow) requires 145F/63C for 30 minutes
• High temperature short term pasteurization (HTST) requires 161F/72C for 15 seconds
• Ultra pasteurization (UP) requires 191F/89C for 1 seconds 
• Ultra high temperature sterilization (UHT) requires 280F/138C for 2 seconds   

The higher up the scale you go, the more microbes are killed. That's why UHT can sit on the shelf for months. Most milk in the U.S. is HTST, and many foods are UP. Check the labels. There is an argument that the low and slow method is more nutritionally beneficial since it kills pathogens without altering milk protein as much as higher temperature pasteurization.

What to do - Thinking about Pasteurization

1. Buy whole foods! If you are choosing pasteurized foods (e.g. milk, juice, almonds), think about the tradeoff between safety, nutrition and value.
2. Safety first. It's the most important thing. If you don't have the time and funds to research nonpasteurized options, don't even think about it and buy pasteurized. If you have the inclination to seek out raw, then do your research.
3. Read the labels. More pasteurized foods may have less nutritional value (they are more processed, after all), but they are also likely to be cheaper and have a longer shelf life before spoiling. Consider your wallet. If you are buying these foods, you are doing a great job anyway, no matter how pasteurized the food is. Food is heated and cooked anyway.

What I ate: 1/4 lb. papaya, 14 oz. green juice, 1 cup Good Earth tea, mixed greens + roasted beets + blue cheese + snow peas + kamut salad, 1 banana, 1 apple, 8 squares dark chocolate, 1 coffee, 1.5 oz. macadamia nuts, 3 oz. cheddar cheese, 1/2 lb. sauteed halibut + spinach, 1 hot chocolate, 40 ounces water.

Exercise: 1 hour yoga