COMPOSITION, TOXIC AND ANTINUTRITIONAL FACTORS OF NEWLY DEVELOPED CULTIVARS OF BRAZILIAN SOYBEAN (GLYCINE-MAX)

Five different recently released Brazilian soybean cultivars (Bays, BR -10, Rio Balsas, Serido and Tropical) were compared for their proximat e analyses and presence of antinutritional or toxic factors. As expect ed, the seeds are rich in proteins, varying from 360.7 to 485.4 g kg(- 1) flour, and they also have a high amount of fat (from 183.0 to 215.3 g kg(-1) flour). Crude extracts from seeds of Bays, BR-10, Serido and Tropical were highly toxic to mice within 1-12 h, depending on the ad ministration route (intraperitoneal, intramuscular or subcutaneous) an d dose used while Rio Balsas was not. These acute effects were very si milar to those produced by the soytoxin, a neurotoxin that has been re cently purified from the commercial soybean sold in Brazil. The amount of trypsin inhibited in the presence of crude extracts ranged from 28 .5 to 62.5 g kg(-1) flour. Urease was also present and the seed lectin agglutinated preferentially rabbit erythrocytes. A heat treatment at 92 degrees C for 1 min destroyed completely the toxic activity while t he haemagglutinating and trypsin inhibitor activities were abolished w ithin 5 min. At these conditions urease was still active. Due to its h igh protein content, lack of soytoxin, and low levels of trypsin inhib itor, lectin, and urease it is suggested that Rio Balsas could be an a lternative for breeding programmes aimed to improve the nutritional qu ality of soybeans.