Protein digestibility and bromatological characterization of soybean genotypes with absence or presence of the trypsin inhibitor Kunitz and lipoxygenases.

摘要: The chemical composition and protein digestibility of 4 soyabean flour varieties with or without the trypsin inhibitor Kunitz (KTI) and lipoxygenases (LOX) and unprocessed or processed at 120°C for 9, 12, 15 and 18 minutes were determined. The chemical contents of the 4 varieties were: ash, 5.86-5.95%; protein, 42.49-44.07%; lipids, 23.53-25.30%; and carbohydrates, 14.65-17.33%. The trypsin inhibitor activity varied from 900 to 1300 mg/g of protein. It was roughly decreased at 120°C. The time needed to completely inactivate the inhibitors in varieties with and without KTI were 18 and 9 minutes, respectively. The in vivo protein digestibility varied from 79.02 to 83.17%. The protein efficiency ratio and net protein ratio of the processed soyabean flour were 1.83-2.75 and 3.03-4.08, respectively. The difference in protein digestibility between flours with KTI processed for 18 minutes and those without KTI processed for …