Influence of Autoclaving Soybean Proteins on Liberation of Aspartic and Glutamic Acids and Lysine by Several Digestion Proceduresa

摘要

SUMMARYPart of the lysine was destroyed when soybean meal or isolated soybean protein mixed with sucrose was autoclaved 4 hr at 121°C. Little or no loss occurred when isolated proteins were autoclaved by themselves.In vitrodigestion with trypsin and erepsin liberated less lysine from the autoclaved than from the unheated soybean proteins if they did not contain the trypsin inhibitor.Partial hydrolysis with hydrochloric acid liberated more aspartie and glutamic acids and lysine from unheated than from heated soybean proteins.Hydrolysis with concentrated hydrochloric acid for 7 days at 40°C andin vitrodigestion with trypsin and erepsin liberated similar amounts of lysine (except for the proteins containing trypsin inhibitors), but acid hydrolysis liberated more aspartic and glutamic acids that did enzymatic hydrolysis.The data support the hypothesis that autoclaving soybean protein formed lysine‐aspartic acid and lysine‐glutamic acid linkages that were resistant to mild hydro