The less heat applied, the better for protein quality. Another factor is how much sugar the supplement contains. When protein and sugar are heated, the Maillard reaction occurs—a chemical version of caramelization, which breaks food down during cooking even as the cooking adds flavor—and the amino acids are damaged. One of the more reactive amino acids under those conditions is the essential amino lysine. When the Maillard reaction damages lysine, it produces a chemical called furosine, and high levels of furosine in a supplement indicate damaged protein. That can lead to reduced protein value and digestibility.
A recent study looked at what happens when various commercial milk-based protein supplements commonly used by athletes are processed. Nineteen ingredients and 13 sports supplements from around the world were analyzed, and the researchers looked at the amount of furosine in each product.
Soy contained the least, mainly because soy isn’t a rich source of lysine. Of the milk proteins tested, casein had the least furosine because casein is processed less than whey. That’s especially true of micellar casein, which is naturally derived and the highest quality available. Whey protein isolate (WPI), which is higher in protein and lower in sugar than whey protein concentrate, had less furosine than WPC. That’s because WPC contains more lactose (6 to 8 percent) than WPI (less than 1 percent). The lactose content makes the protein more subject to the Maillard reaction, leading to amino acid damage.
What does all of that mean for you, the consumer? Stick with higher-quality protein that features whey protein isolates as the primary whey ingredient. WPI contains an average 86.8 percent protein (higher quality forms are over 90% protein due to the lack of lactose and fat content) compared to the 29 to 89 percent found in WPC, although most WPC used in protein supplements average 70-80% protein..The higher lactose and fat content of WPC makes it a filler protein, which saves the manufacturer money but may result in the premature degradation of the product. Note that a high level of furosine reduces the availability of the other proteins, leading to poorer nutritional effect.You should also be aware that because of the recent wholesale cost rise in whey proteins, many companies are substituting WPC instead of the higher quality WPI. But they are not indicating this on the label, and have not reduced the cost of the products, despite paying less for raw material. Isn't that nice?
Henares-Rufian, J.A., et al. (2006). Assessing nutritional quality of milk-based sport supplements as determined by furosine. Food Chemistry. 101:573-78.
©,2012, Jerry Brainum.Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
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