The combined application of extrusion and enzymatic technology for extraction of soybean oil

Abstract

This paper desctibes a new technological process for soybean oil extraction. The process deals with the combined effect of thermoplastic extrusion of beans and the subsequent action of hydrolytic and proteolytic enzymes in aqueous medium to recover the oil, thus, avoiding solvent application. The thermoplastic extrusion is hndamental for the process, because it facilitates the action of enzymes in oil containing cells, reduces the non-hydratable phosphatides and promotes protein denaturation by reducing the emulsion stability and thus enhancing the oil extraction. The main parameters affecting the oil yield are: the temperature and diameter of the die in the extrusion process, the dilution, the concentration of enzymes and the incubation time of the enzymatic treatment.'Ihe highest yield was obtained under the following conditions: extrusion of beans at 9OoC and exit die of 6 mm, enzymatic incubation time of 6 h, extruded soylwater dilution ratio 1:lO and concentration of enzyme 6%. With these conditions 88% of the oil were obtained after centrifugation. Moreover, the aqueous enzymatic extraction is easier than solvent extraction, and leads to high value products: a solvent-free meal more suitable for human consumption, a protein hydrolysate that can be used as ingredient for liquid foods and an oil of better quality. The non-hydrolyzed meal contains ca 25% of original soybean protein and the residual oil. The protein hydrolysate in the liquid phase contains ca 75% of the total protein in the original grain with a molecular weight below 20 kDa.

Flaking and extrusion as mechanical treatments for enzyme‐assisted aqueous extraction of oil from soybeans

“…Oil and protein extraction recoveries for 0.5% Multifect Neutral over the control increased by 29 and 48%, respectively. Our 88% oil extraction recovery with protease was similar to values reported by Freitas et al (20) from unflaked, dehulled soybeans following extrusion and enzyme-assisted AEP by using a cellulase and a protease, although we used acid hydrolysis determination of total fat and they used a free fat determination, in which we have less confidence (see later discussion about bound and free fat). Comparison of the amounts of enzyme required or incubation period is not meaningful given the variation between the studies in extrusion conditions, starting material, and enzyme activity and concentration used.…”

Separating Oil from Aqueous Extraction Fractions of Soybean

“…We have shown that enzyme-assisted AEP of extruded full-fat soy flakes achieves nearly 90% oil extraction from insoluble solids [6]. Other reports on EAEP of extruded substrates include whole soybeans [8] and sunflower kernels [9]. These reports and those of our own indicate that extrusion is key to increasing oil recovery by rupturing cell walls, denaturing protein, and facilitating protease action on denatured protein including oleosin.…”

Mechanisms of Aqueous Extraction of Soybean Oil

“…The use of protease and cellulase enzymes has also had significant effects on oil extraction yield from soy flours and extrudates in processes referred to as enzyme-assisted aqueous extraction processing (EAEP) (1,6,8,9). In soy, there is an association between protein solubility and oil extraction.…”