Establishment of an aqueous method for extracting soybean oils assisted by adding free oil

Abstract

Concern for the environment, safety and costs has promoted the development of the method for extracting soybean oil by an aqueous process. An advanced aqueous extraction of soybean oil assisted by adding free oil was established in this study, which recovered 81% of the oil from soybeans with 20.73% crude oil content and produced a de-oiled residue with 4.7% residual oil. The acid or peroxide value of the recovered oil met the Chinese national standard for first class refined oil, which was lower than that produced by solvent extraction or high temperature pressing. No wastewater was produced during the aqueous extraction of oil. The removal of the oil by the addition of oil and a small amount of water generated a residue (solids) containing all the protein, which represents 2/3 of the revenue in the soybean process. The protein-rich residue can be further processed to produce a protein isolate with high purity (e.g. > 90%) by using a higher amount of water. It can also be used as a nutritious ingredient or raw material for the production of many food products, among other applications.