NUTRITIONAL VALUE OF HEAT TREATED WHOLE SOYBEANS

Abstract

The heat treatment of whole soybeans was investigated, with consideration for oven temperature, process time and the initial moisture content of the beans, with a view to optimizing the removal of the toxic factors and enhancing the feed utilization of the soybean. Two purified diets equal in both crude protein level and classical metabolizable energy level were used. One of the diets consisted of ground whole soybeans (both heat treated and raw), whereas the other diet, containing commercial soybean meal as the only source of protein, provided the control for the tests. Male, White Leghorn cockerel chicks were selected on a weight basis and randomized in battery pens. The experimental treatments were assigned at random to pens and the chicks were provided feed and water ad libitum. Three experiments were conducted using soybeans with initial moisture of 10, 12.5 and 16% and heat treatment for 10, 5 and 3 minutes in a still-air oven within a temperature range of 149–246 C. Certain combinations of time and temperature not only promoted weight gains and feed efficiencies superior to those of the commercial diet, but also resulted in minimal pancreatic hypertrophy. The data obtained reaffirmed that a critical quantity of heat is required to deactivate the toxic factors and to ensure maximum nutritive availability.