Characteristics and use of okara, the soybean residue from soy milk production--a review.

Large quantities of okara produced annually pose a significant disposal problem. It contains mostly crude fiber composed of cellulose, hemicellulose, and lignin, about 25% protein, 10-15% oil, but little starch or simple carbohydrates. It is a suitable dietary additive in biscuits and snacks because it reduces calorie intake and increases dietary fiber. The high-quality protein fraction has good water holding and emulsifying qualities and contains a peptide with anti-hypertension effects. The pectic polysaccharides fraction is suitable for thickening acid milk products. Okara fermented with Actinomucor elegans (meitauza), Aspergillus oryzae (koji), Neurospora intermedia (ontjom), and Rhizopus oligosporus (tempe), on consumption, reduces cholesterol level and contains substances that counteract dietary free radicals. Unique and useful products produced by Bacillus subtilis and Penicillium simplicissimum on okara include surfactin and iturin A (fungicidal), okaramines A, B, D-F (D is insecticidal), an oleanane triterpene, and two dihydroquinolinones (one toxic for Artemia salina). Okara has been used as silkworm food and in the production of ceramics.