Biovalorization of soybean residue (okara) via fermentation with Ganoderma lucidum and Lentinus edodes to attain products with high anti-osteoporotic effects.

Okara, despite being a soybean processing by-product, still holds many nutrients. Thus, considerable attention has been recently paid to its reuse. In this study, solid-state fermentation was performed using Ganoderma lucidum and Lentinus edodes. Antioxidant activity and bioactive compound levels in G. lucidum-fermented okara (GLFO) and L. edodes-fermented okara (LEFO) were assayed. Antiosteoporosis bioactivity was evaluated using an animal model. The results demonstrated that solid-state fermentation significantly improved the antioxidant activity and bioactive compound levels. Furthermore, GLFO and LEFO increased trabecular bone volume, although only the GLFO-treated group exhibited significantly improved trabecular separation compared with the bilateral ovariectomy-treated control group. GLFO-related outcomes were superior to those of LEFO. The results demonstrate that okara products are effective for treating postmenopausal osteoporosis in humans.