Characterization and stability of bioactive compounds from soybean meal

•We investigated soybean cake bioactive compounds and their stability.•High moisture thermal processing of cakes may improve its functional value.•Solvent but not storage conditions influenced soybean cake extracts stability.•Dry extracts are suitable for performing long-term in vivo studies.

In the present study we characterized soybeans and soybean meals, which is the high protein co-product of soybean oil extraction, produced at industrial or laboratory scale. Additionally, for the purpose of future metabolic and bioactivity in vivo studies, we conducted, for the first time, a 6-month stability study of soybean meal dry extracts. Soybean meal extracts were obtained either by ethanol or a ternary solvent mixture composed of water, ethanol and ethyl acetate (40:40:20). Soybean meals presented 43% higher protein content, from 29% to 101% higher bioactive compounds contents and 52% higher antioxidant capacity than soybeans. High moisture thermal procedure employed during soybean meal processing led to a 13-fold increase in aglycone isoflavones contents, which could affect the bioavailability of isoflavones in this residue. In addition to a 29-fold higher extraction yield, bioactive compounds showed higher stability in ternary solvent mixture extracts in comparison to ethanol, independently of the sample or storage conditions. We concluded that dry soybean meal extracts are suitable materials for performing long-term in vivo studies, as these extracts were stable when stored at room temperature unprotected from light for 180 days.