OBJECTIVE: The aim of this study was to evaluate the effect of processing on the protein quality of new soybean cultivars intended for human food. METHODS: The diets were prepared from the cultivars Embrapa 48, BRS 213, BRS 155 and UFVTN 105. They were heat-treated in a vacuum oven at 130ºC and 150°C, with subsequent removal or not of the hull for the production of soybean meals. A biological assay was done to determine the protein efficiency ratio, net protein ratio and true protein digestibility. RESULTS: Soybean meals had lower protein efficiency ratio, net protein ratio and digestibility than casein. Whole soybean meals treated at 150ºC had a better protein quality index than refined soybean meals heat-treated at 130ºC. The protein efficiency ratio and net protein ratio of Embrapa 48 and BRS 155 cultivars were higher (p<0.05) than the other ones. The UFVTN 105 cultivar had the highest digestibility (p<0.05) when treated at 130ºC. Among the cultivars heat-treated at 150ºC, the BRS 213 and BRS 155 cultivars had the lowest digestibility (p<0.05). Protein digestibility of the cultivar with low trypsin inhibitor content (BRS 155) was not better than that of the conventional Embrapa-48 cultivar. CONCLUSION: Heating and removal or not of the hull affected the protein quality of the new soybean cultivars intended for human food. Whole soybean meals heat-treated at 150ºC for 30 minutes presented the best results. Heating improved the protein quality of the conventional soybean meals. Their protein quality was similar to that of the cultivars without trypsin inhibitor and better than that of the cultivars without lipoxygenases.
Feeding; Digestibility; Food handling; Protein quality; Soybean
