Avalia??o bioquímico-nutricional de uma linhagem de soja livre do inibidor de tripsina Kunitz e de lectinas

摘要

Soybean seeds contain protein anti-nutritional factors, protease inhibitors, and lectins, which limit their use in human and animal nutrition. Aiming to reduce these factors in soybean seeds, a genotype devoid of Kunitz Trypsin Inhibitor (KTI) and Lectin (LEC) was developed by the Breeding Program for Soybean Quality of the Biotechnology Institute (BIOAGRO) of the Federal University of Vi?osa, Minas Gerais, Brazil. The present work aimed at the biochemical and nutritional characterization of this soybean genotype. The protein nutritional quality and intestinal morphological alterations were determined in Wistar rats fed with diets based on soy flour and casein. The trypsin inhibitory activity in normal genotype KTI+LEC+ was approximately 2.8 times greater than that of the KTI-LEC- genotype. The PER, NPR, and NPU values obtained after thermal treatment were better for the commercial variety than those of the KTI-LEC- genotype. The protein digestibility of the KTI-LEC- soybean was higher than that of the commercial genotype KTI+LEC+. The digestibility values in animals fed with thermally treated KTI-LEC- soybean flour was close to that observed in animals fed with casein. The animals fed with thermally treated KTI+LEC+ soybean flour also presented higher levels of morphological alterations in their intestinal vilosities when compared to those fed with KTI-LEC- soybean flour. It can be concluded that the genetic elimination of KTI and LEC positively impacted soybean protein digestibility, however, there was no improvement on its nutritional value.