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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Research Project #447330

Research Project: Enhancing Soybean Meal Protein Quality Assessment: A Gastric Fluid Approach

Location: Plant Genetics Research

Project Number: 5070-21000-044-034-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2024
End Date: Sep 30, 2025

Objective:
Several studies have shown the negative effect of trypsin inhibitor (TI) on the growth performance of monogastric animals. These studies have led to the general conclusion that the lower TI in animal feed the better the growth performance. With USB funding, we have measured the trypsin inhibitor activity (TIA) and Bowman-Birk inhibitor activity (BBIA) of several hundred soybean meal (SBM) samples. Our research has shown that, despite the easy detection of both TI and BBI protein in the majority of commercial SBM samples, these proteins had very little protease inhibitor activity presumably due to heat treatment. Thus, one would want to reevaluate the notion that protease inhibitors are to blame for subpar animal performance given the extremely low levels of inhibitor activity found in these samples. SBM is subjected to heat treatment to destroy protease inhibitors. Overheating, a common problem with roasting, reduces protein quality. The objective of this proposal is to determine whether variations in heating have influenced the protein solubility and digestibility of commercial SBM samples.

Approach:
Potassium hydroxide solubility test is acknowledged as an important technique for evaluating the protein quality of SBM for animal feed. With USB funding, we have identified several commercial SBM samples that show variation in trypsin and chymotrypsin inhibitor activity. These samples along with SBM samples that have been subjected to varying processing temperatures and various processing methods will be obtained from feed processors, we will determine the KOH-protein solubility of these SBM samples. Briefly, 1.5 grams will be extracted with 75 ml of 0.2% KOH solution for 20 min on a magnetic stir plate. This slurry will be subjected to centrifugation and the nitrogen content in the resulting supernatant and the original SBM sample will be determined by Kjeldahl method. The nitrogen values will be multiplied by 6.25 to yield crude protein and protein solubility will be calculated as a percentage of the total in the original SBM sample. We believe that this procedure can be significantly improved by simplifying and eliminating unnecessary steps inherent in this method. Hence, during the initial phase of this study we will conduct experiments to simplify the previously published procedure.