SOYBEAN AND HEALTH - University of Macau Library

386Soybean and Healthfood-processing by products, can be used in the tempe fermentation (Feng, 2006; Nout &Kiers, 2005).Fig. 3. Production process of soya bean tempe.The main process operations that differ according to the use of various substrates used intempe fermentation are the selection of optimum pre-treatments such as de-hulling,optimum soaking conditions or duration of boiling. The process of tempe manufacture fromsoya beans is shown in figure 3. The process starts with the de-hulling of the soya beans,which can be done manually by rubbing the seed coats from soaked soya beans, or bymechanical abrasion of dry beans. In the Netherlands, tempe manufacturers purchase dryde-hulled soya beans, ready for use. The soya beans are soaked for 6-24 h, in order to: (1)increase the moisture content of the beans, (2) to enable microbial activity in the soakingwater, (3) render the beans edible and (4) to extract naturally occurring antimicrobialsubstances (saponins) and bitter components.Some manufacturers add lactic or acetic acid or naturally acidified soaking water “backslop”(Nout et al., 1987) at the start of the soaking, to control microbial spoilage.Subsequently, the soaking water is discarded and the beans are cooked for 20-30 minutes infresh water. After cooking, the cooking water is discarded and the beans are spread out onperforated trays to remove free water, steam-off and achieve a rapid cooling. When workingat a large scale, basket centrifuges are used to remove the cooking water. The cooled soya