ABSTRACTChemical composition and protein value of a tempeh‐related food using lupine as substrate was determined. Bitter lupine grits were slowly degraded as compared to sweet lupine, pointing out the inhibitory action of lupine alkaloids. Any fungal degradation of the latter could be determined. Sweet lupine tempeh was further characterized. Water‐soluble substances increased during the first 17 hr and then only slight changes occurred. The lipid fraction was preferentially metabolized by the fungus, reaching almost 50% loss after 45 hr fermentation. Linolenic and erucic acids were particularly degraded. No significant increase of the NPR values or protein digestibility of fermented lupine were observed. Preliminary results of sensory evaluation of deep‐fat fried lupine tempeh were promising.