Q While cooking my St. Patrick's Day corned beef, I noticed a large amount of foam that formed on top of the boiling liquid. What causes this?
A That foam is made of proteins released from the cooking meat, says Jeff Sindelar, a meat scientist in the UW-Madison Meat Laboratory.
Meat is about 15 to 17 percent protein and contains three different types: sarcoplasmic protein, which is water-soluble and gives meat its characteristic red (fresh), pink (cured), brown (old) or purple (vacuum-packaged) color; myofibrillar protein, which forms the contractile fibers of meat and gives it its texture; and stromal protein, which makes up collagen and other connective tissues.
The foaming effect is caused by the water-soluble proteins and may be especially noticeable when cooking a product like corned beef or pastrami that is "enhanced" with a spiced or flavored solution.
"During cooking at high heat, some of that water comes back out of the meat and with the water is a small amount of sarcoplasmic protein. At high temperatures that protein denatures and assumes a foamy, frothy appearance," Sindelar explains.
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