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Effect of Moisture Content and Cooking Time on Soybean Meal Urease Index, Trypsin Inhibitor Content, and Broiler Growth

1980; Elsevier BV; Volume: 59; Issue: 10 Linguagem: Inglês

10.3382/ps.0592300

1525-3171

J.L. McNAUGHTON, F.N. REECE,

Protein Hydrolysis and Bioactive Peptides

Soybean meal (SBM) was solvent-extracted at a commercial processing plant and subjected to added moisture and cooking time treatments. Results in Experiments 1 and 2 indicated that regardless of cooking time, the addition of either 10 or 25% moisture to raw SBM prior to either autoclaving or dry heating decreased urease index. Results in Experiments 3 and 4 indicated that when raw SBM contained either 0, 4, 8, 12, or 16% added moisture and autoclaved at 120 C in sealed containers from 0 to 135 min with 15-min intervals, urease and trypsin inhibitor contents decreased with either increasing added moisture or cooking time. With 16% moisture, either 30 or 45 min of cooking time was required to decrease urease index and trypsin inhibitor contents, respectively, to an acceptable level. Raw SBM autoclaved with less than 12% moisture contained urease and trypsin inhibitor contents considered excessive, regardless of cooking time. Raw SBM autoclaved for either 60 min at 12% or 30 min at 16% moisture showed lysine degradation when compared to SBM autoclaved for shorter periods of time. Increasing moisture and cooking resulted in decreased trypsin inhibitor and urease contents, increased broiler growth, improved feed efficiency, and decreased pancreas hypertrophy. Trypsin inhibitor was found in Experiment 5 to be a more reliable criterion for determining processing adequacy than was urease index. These data indicate that both SBM moisture and cooking time affected urease, trypsin inhibitor contents, and broiler growth, and that urease and trypsin inhibitor destruction during heat treatment immediately precedes lysine degradation.