UHT Milk

asturianaI grew up in the United States and had only ever drunk cold, pasteurized milk.  I love milk, I love breakfast cereal with milk, I love chocolate milk, I even used to make this weird concoction I called “maple” milk by mixing in maple syrup.  When I moved to Spain I noticed that most of the milk was not in the refrigerated section, but in cardboard box-like containers or plastic opaque bottles on the regular beverage shelf.  Most of the milk drunk in Spain is UHT (ultra high temperature) milk.  I had never had UHT milk…..I knew about Parmalat, the company that brought it to the US in the 1990s, but I had never tried any.  How bad could it be?

“Yuck. This tastes burnt!” I said.  “No wonder it’s in an opaque bottle, they don’t want us to see what it looks like.”  It looked like normal milk, but tasted like it had been cooked.  Incidentally, I found out, it’s kept in opaque bottles or cardboard boxes because light breaks down milk proteins, and it wouldn’t last as long on the shelf.

The official U.S. government definition of an ultra-pasteurized dairy product stipulates “such product shall have been thermally processed at or above 135° C (280° F) for at least 2 seconds, either before or after packaging, so as to produce a product which has an extended shelf life.”  This doesn’t sound like it could do too much damage (it’s only 2 seconds), but it does!

According to Wikipedia, UHT milk has a shelf life of 6 to 9 months (until opened). When the world’s foremost UHT milk processor, Parmalat, first introduced UHT milk to the U.S. market back in 1993, they hit a snag. Americans distrust milk that hasn’t been refrigerated. We like our milk cold, and UHT milk doesn’t need to be refrigerated.

So, what’s wrong with UHT processing?  The introduction to a 2005 study published in the Journal of Dairy Science highlighted the current problems with UHT processing from an industry point of view:

“Often, heat treatment causes milk-fat globule membrane proteins and whey proteins to unfold such that buried sulfhydryl (-SH-)groups, normally masked in the native protein, are exposed to the outer surfaces (Hoffmann and van Mill, 1997). In turn, these processes produce extreme cooked flavors, often attributed to changes in the sulfhydryl and disulfide content of the protein fraction (Swaisgood et al., 1987). Conventional pasteurization methods have long been in place and with the advent of UHT technology, the sterilization of fluid milk was achieved using higher temperature treatments for shorter periods. However, shelf-stable milk has met with limited acceptability by the consumer, especially in the United States, due in part to a high cooked flavor. Several attempts to improve the quality of UHT-treated milk products proved successful to varying degrees. Previously, Swaisgood and coworkers used immobilized sulfhydryl oxidase to reduce the thiol content of UHT-heated skim milk and described an improved flavor after enzymatic oxidation to form protein disulfide bonds (Swaisgood et al., 1987).Other studies have showed that altering UHT processing parameters, such as indirect vs. direct steam injection systems, cooling rates, and long-term storage conditions have a significant impact on sensory attributes (Browning et al., 2001). Most recently, epicatechin, a flavonoid compound, was added to UHT milk prior to heating, and the results revealed partial inhibition of thermally generated cooked aroma (Colahan-Sederstrom and Peterson, 2005).”

parmalat

So for decades, UHT processors have known that UHT processed milks results in a “high cooked flavor,” and they’ve done all kinds of experimenting to get rid of the nasty taste and smell (even resorting to adding flavonoid compounds to the milk to try to negate the off-flavor).  Okay, so it tastes funny compared to normal milk. And maybe it smells funny too. But what makes UHT processing any worse than regular old pasteurization?  According to Lee Dexter, microbiologist and owner of White Egret Farm goat dairy in Austin, Texas, “ultra-pasteurization is an extremely harmful process to inflict on the fragile components of milk.” Dexter explains that milk proteins are complex, three-dimensional molecules. They are broken down and digested when special enzymes fit into them like a key into a lock. Rapid heat treatments like pasteurization, and especially ultra-pasteurization, actually flatten the molecules so the enzymes cannot fit any more. If such proteins pass into the bloodstream (a frequent occurrence in those suffering from “leaky gut,” a condition that can be brought on by drinking processed commercial milk), the body perceives them as foreign proteins and mounts an immune response. That means a chronically overstressed immune system and much less energy available for growth and repair.  Now I know why I never felt completely well when I lived in Spain.

No wonder more and more people are starting to think of themselves as intolerant to casein (the protein found in milk). Not only do pasteurization and UHT processing kill off the enzymes present in milk needed to digest the casein, the casein itself is altered to the point of being indigestible!  This is a new kind of “intolerance” to milk.  Lactose be damned, casein intolerance is taking over!

The main reason that UHT milk annoys me is that it has a destroyed flavor.  Growing up with regular, old pasteurized milk, I was used to a “raw” milk flavor.  The UHT milk just tastes like it’s been processed.  It tastes “cooked!”  Thank goodness most of the milk you find in Singapore is fresh milk that has been regularly pasteurized.  It feels just like home!

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