FOOD SCIENCE ›› 2020, Vol. 41 ›› Issue (1): 68-73.doi: 10.7506/spkx1002-6630-20181112-134

• Basic Research • Previous Articles     Next Articles

Correction for the Determination of in Vitro Digestibility of Grain Proteins

LIU Yanmei, ZHOU Xueyong, FU Rongxia, Angadi Honnursab RAJASAB, XIAO Jianzhong   

  1. (1. Tianjin Engineering and Technology Research Center of Agricultural Products Processing, College of Food Science and Bioengineering, Tianjin Agriculture University, Tianjin 300384, China; 2. Faculty of Science & Technology, Gulbarga University, Gulbarga 585308, India; 3. Tianjin Heima Industry and Trade Limited Company, Tianjin 301711, China)
  • Online:2020-01-15 Published:2020-01-19

Abstract: The procedures with and without the addition of trichloroacetic acid (TCA) to determine the in vitro digestibility of cereal proteins are currently available in the literature, both of which feature unregulated deduction of background. The aim of this study was to verify the effect of TCA on the determination of the in vitro digestibility of grain proteins. Four kinds of grains (rice, corn, millet and quinoa) were hydrolyzed by pepsin and trypsin through a two-step procedure. Comparative experiments with and without TCA addition before filtration of the hydrolysates were carried out. Results showed that the protein digestibility values determined by direct filtration without TCA addition were 2.85%, 3.42%, 15.97% and 18.74% higher than those with TCA addition for the four hydrolysates, respectively. However, the values from the latter method decreased by 3.39%, 2.92%, 2.15% and 1.78%, respectively when the background values of pepsin and pepsin were not deducted. Based on these experimental results, a modified formula for the accurate determination of grain protein digestibility by TCA precipitation was proposed. Therefore, it is recommended to add TCA to the protein hydrolysates in the determination of grain protein digestibility in vitro and simultaneously to deduct correctly the blank control values of pepsin and trypsin.

Key words: grain protein, protein precipitator, trichloroacetic acid, digestibility of protein

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