Fate of oligosaccharides during production of soya bean tempe

The concentrations of the flatulence and possibly prebiotic oligosaccharides, stachyose and raffinose, as well as sucrose, glucose and fructose, were monitored during the preparation of bacteria-free tempe made with Rhizopus oligosporus NRRL 2710. The initial soya beans contained (g [kg dry matter]−1): stachyose, 30; raffinose, 11; sucrose, 57, glucose, <0.1, and fructose, <0.1. Losses of oligosaccharides during preparation of tempe were due to leaching during the hydration (100°C for 30 min), washing (60°C) and cooking stages (121°C for 10 min). The losses were (g [kg dry initial soya bean]−1): hydration 45; dehulling and washing, 14, and cooking, 24. Concentrations remaining in the cooked cotyledons were (g [kg dry weight]−1): stachyose, 7.0; raffinose, 2.1; sucrose, 7.2; glucose, 1.8, and fructose, 0.9, representing 17% (w/w) of the stachyose, 15% of the raffinose and 13% of the sucrose+glucose+fructose in the initial soya beans. Within the errors of measurement, concentrations of stachyose, raffinose and sucrose did not change during the fermentation but concentrations of glucose and fructose were reduced to 0.2 and 0.3 g (kg dry weight)−1, respectively. The results are discussed in relation to controlling the concentrations of oligosaccharides in tempe.