The effect of thermal treatment of whole soybean flour on the conversion of isoflavones and inactivation of trypsin inhibitors.

The soybean (Glycine Max. (L) Merrill) is a leguminous which originated from China and has been cultivated in this country for around five thousand years. It was considered for centuries the staple food of the countries of East Asia. In the West, its introduction was made experimentally in the Europe in 15th century. In the USA the first reports of cultivation of soybean date from 1765. Unlike East Asia, the USA soybean was initially cultivated as forage plant being used as a source of edible oil starting at 1915. A major technological progress for the use of soybean meal as protein source in nutrition was made in 1917, when Osborne and Mendel demonstrated that unheated soybean meal presents nutritional quality lower than that of heated soybean meal. Thus, the finding of the nutritional value of soybean meal as a feed for animal nutrition, coupled with growing demand for vegetable oils allowed the deployment of many industries for the processing of soybeans in the USA (Muller, 1981). In Brazil, the introduction of soybeans occurred in Bahia state, in 1882 (Bonetti, 1981). But the first statistics showing the use of soybean for grain production are from 1941. In this same year, the first soybean processing industry in the country was installed in Rio Grande do Sul (Teixeira, 2003). However, only from the 1960, soybean crop became important in the country, initially in the South where it showed better adaptation because of the similarity with regions of cultivation in southern United States. From the 70's, the soybean crop has evolved significantly in the cultivation states, not only in the south, but also in the middle western of Brazil. With the development of new cultivars adapted to different agro-climatic regions of the country, Brazil has become the second largest soybean producer in the world. Advances in new technologies for increased acceptability of soy proteins as human food occurred as result of protein deficiency worldwide, after the World War II. Since the 1950’s, USA and Canadian public research institutions worked on the development of soybean cultivars for human food use for export, mainly to Japan. In 1999, there were 16 breeding programs in public institutions working on soybean for human consumption (food-type). By

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Nutritional and Bioactive Compounds of Soybean: Benefits on Human Health

Soybeans present commercial and nutritional importance, but they contain some components that decrease the availability of some nutrients. Germination has a positive effect on the increase of the nutritional quality of the grain due to the changes that occur in the process because of the difference in vegetable kind, variety of seed, and the germination conditions. The objective of this research was to analyze soybean grains before and after 48 hours germination. Centesimal composition, tripsin inhibitor, phytic acid, tannins, total phenolics, availability and amount of in vitro iron, in vitro protein digestibility and antioxidant activity analysis by DPPH and ABTS were performed. The germination process altered the chemical composition of the grain and the iron and protein availability. The results showed that germination reduced tannins, available carbohydrates, and the antioxidant activities by DPPH and ABTS methods. The germination process increased the moisture, lipid, protein, soluble fiber, in vitro protein digestibility, and total phenolics of the grain. Germination did not alter significantly the content of ash, insoluble fiber, amount of iron and its availability, phytic acid, and tripsin inhibitor. Although germination time was low, changes occurred in the grain composition promoting increase in the nutritional quality.

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Alterações químicas em grãos de soja com a germinação

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.

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Influência do processamento na qualidade proteica de novos cultivares de soja destinados à alimentação humana

Soybean sprouts are vegetables for direct consumption obtained from germinated grains, which have been used for centuries in Eastern countries. Their nutritional characteristics and ease of production have attracted the attention of consumers from Western countries. Small seeds with high germinating power and vigour are inherent qualities for shoot production. At the Brazilian Agricultural Research Corporation - Embrapa, these characteristics have been considered in the genetic breeding program to obtain special soybean cultivars for human consumption. The aim of this study was to produce and characterize the quality of soybean sprouts from the genetic lines BRM09-10505, BRM10-60599 and PF133002, in comparison with the cultivar BRS 216, which was developed for use as sprouts and natto. Trays placed in a growth chamber (25 °C and 99% relative humidity) were used for produce the sprouts. The protein, lipid, ash, isoflavones, Kunitz trypsin inhibitor and phytic acid contents were analysed in the seeds and sprouts. The length and weight of the sprouts were also determined. Seeds of the line BRM09-10505 showed 95% germinating power followed by BRS 216 (93%) and the other lines (88% on average). Germination, by mobilizing chemical compounds, increased the protein (8.96%) and isoflavone (56.00%) contents, and reduced the concentrations of the Kunitz trypsin inhibitor (26.91%) and phytic acid (13.78%). The cultivar BRS 216 presented the highest protein content in the seeds (41.96 g.100 g-1) and sprouts (47.70 g.100 g-1). The line BRM09-10505 had the highest trypsin inhibitor content in the seeds (27.56 mg IT g-1) and in the sprouts (19.62 mg IT g-1); the highest total isoflavone contents in the seeds (340.10 mg.100g -1) and in the sprouts (406.38 mg.100 g-1); and the lowest phytic acid content in the sprouts (1.13 g. 100 g-1). After four days of germination, the length and weight of the sprouts were, respectively, 8.03 cm and 214.36 g for line BRM09-10505 and 7.31 cm and 140.93 g for BRS 216. Of the lines tested, BRM09-10505 showed good potential for sprout production.

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Brotos de linhagens genéticas de soja: avaliação das propriedades físico-químicas

A soja (Glycine max (L.) Merrill) e uma das leguminosas mais estudadas, em virtude de sua intensa utilizacao como fonte de oleo comestivel e proteina para alimentacao humana e animal. A presenca de inibidores de tripsina na soja limita sua utilizacao, tornando necessario o processamento termico para melhorar sua qualidade nutricional. Entretanto, o processamento termico excessivo ou inadequado pode reduzir a qualidade da proteina. Neste trabalho, foram utilizados cultivares de soja BR-36, com atividade normal de inibidores de tripsina, e cultivares BRM 95-5297 e BRM 95-5262, com baixas atividades de inibidores de tripsina. As farinhas com 10 e 16% de umidade foram aquecidas em banho a 95°C, com cinco intervalos (15, 25, 50, 75 e 100 minutos) de retencao; em seguida, foram determinados os respectivos parâmetros cineticos de inativacao de inibidores de tripsina e de insolubilizacao de proteinas. A partir da cinetica de primeira ordem para inativacao de IT e insolubilizacao de proteinas, observou-se que as constantes de velocidade de reacao de inibidores de tripsina aumentaram, com consequente reducao no tempo de processamento termico dos cultivares de soja BRM 95-5297 e BRM 95-5262 quando comparados ao cultivar BR-36. O acrescimo de 6% de umidade nas farinhas tambem aumentou as constantes de velocidade de inativacao de inibidores de tripsina e de insolubilizacao de proteinas.

https://www.rbz.org.br/wp-content/uploads/articles_xml/1516-3598-rbz-S1516-35982005000500028/1516-3598-rbz-S1516-35982005000500028.pdf

Edna Mayumi Yuahasi Miura

Papers

Cinética de inativação de inibidores de tripsina e de insolubilização de proteínas de diferentes cultivares de soja