Reduction in Phytic Acid Levels in Soybeans During Tempeh Production, Storage and Frying

Tempeh was prepared from Delmar variety soybeans inoculated with the traditional Indonesian inoculum (usar) and two pure culture strains of the mould Rhizopus oligosporus (BTU3K1 and CT11K2). The preparatory treatments during tempeh production decreased the phytic acid content (% dry weight) of soybeans, except for the fist soaking which significantly increased the phytic acid content. The phytic acid content of soaked soybeans was halved during tempeh fermentation and was further reduced when tempeh was stored for 72 hr at 5° and at 30°C. Deep fat frying of tempeh in peanut oil further halved the phytic acid content. Less than 10% of the phytic acid remained after tempeh fermentation, storage and frying.