The Journal of nutrition
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The Journal of nutrition · Jan 1992
Determining optimal heat treatment of soybeans by measuring available lysine chemically and biologically with rats to maximize protein utilization by ruminants.
Soybeans were heated in a forced air oven at 120 and 130 degrees C for 60 and 180 min, and at 140, 150 and 160 degrees C for 10, 30, 60, 90 and 120 min. Two types of measurements were used to determine optimal heat treatment of soybeans to maximize protein utilization by ruminants. One was to estimate the rate and extent of protein degradation in the rumen using an in vitro ruminal system. ⋯ As temperature increased, the time required to maximize post-ruminal available lysine decreased. The optimal heat treatment for soybeans heated in a forced air oven was: 140 degrees C for 120 min or greater, 150 degrees C for 60 min or 160 degrees C for 30 min. A loss of 15-22% of chemically determined available lysine was necessary to achieve the heat treatment that resulted in maximal post-ruminal available lysine.