Obtaining an agronomic/environmental biostimulant by enzymatic hydrolysis of okara

Abstract

In the present work, an enzymatic process has been developed for the valorization of okara, through its conversion into an agronomic/environmental biostimulant product with high bioavailability and high content in C, N, P and K. Okara is an insoluble by-product resulting from the process of obtaining soy milk and tofu. Although it has a high nutritional value (proteins, fiber and lipids), where its composition of bioactive compounds such as isoflavones, vitamins and trace elements stands out, it presents problems of utilization due to its high water content, which makes it a very perishable and easily fermented product. All this makes it an ideal substrate for obtaining agronomic/environmental compounds. The process is based on the use of different hydrolytic enzymes, which lead to the solubilization and hydrolysis of organic (proteins and sugars) and inorganic (P and K) molecules. The enzymatic process designed consists of a sequential multi-enzymatic hydrolysis involving proteases, phytases and carbohydrolases. The enzymatic extract has been chemically characterized, highlighting its high content in peptides and free amino acids (soluble organic content composed of 64% of molecules <1 KDa, solubilization of 61% of total proteins), as well as in organic phosphate (solubilization of 79.1% of total P), K (solubilization of 86.6% of total K) and free glucose.