Enzyme‐Assisted Aqueous Extraction of Oil and Protein from Soybeans and Cream De‐emulsification

Abstract

The effects of two commercial endoproteases (Protex 6L and Protex 7L, Genencor Division of Danisco, Rochester, NY, USA) on the oil and protein extraction yields from extruded soybean flakes during enzyme-assisted aqueous extraction processing (EAEP) were evaluated. Oil and protein were distributed in three fractions generated by the EAEP: cream + free oil, skim and insolubles. Protex 6L was more effective for extracting free oil, protein and total solids than Protex 7L. Oil and protein extraction yields of 96 and 85%, respectively, were obtained using 0.5% Protex 6L. Enzymatic and pH treatments were evaluated to de-emulsify the oil-rich cream. Cream de-emulsification generated three fractions: free oil, an intermediate residual cream layer and an oil-lean second skim. Total cream de-emulsification was obtained when using 2.5% Protex 6L and pH 4.5. The extrusion treatment was particularly important for reducing trypsin inhibitor activity (TIA) in the protein-rich skim fraction. TIA reductions of 69 and 45% were obtained for EAEP skim (the predominant protein fraction) from extruded flakes and ground flakes, respectively. Protex 6L gave higher degrees of protein hydrolysis (most of the polypeptides being between 1,000 and 10,000 Da) than Protex 7L. Raffinose was not detected in the skim, while stachyose was eliminated by a-galactosidase treatment.

Mechanisms of Aqueous Extraction of Soybean Oil

“…It is not obvious based on these images why the addition of protease results in the increased release of oil. In the extruded material, however, the effect of protease is more pronounced, increasing yield from 68% to between 88% and 96% (1,8). Likewise, the extracted residual is drastically altered by the addition of protease ( Figure 4D).…”

“…AEP uses water as an extraction medium, dissolving soluble cellular materials and allowing the release of oil into the bulk liquid phase, from which the oil can be recovered by centrifugation resulting in a cream emulsion which can be broken to recover free oil (1)(2)(3). Approximately 10-15% of the oil released from the solid fraction also remains in the aqueous fraction as an emulsion stable toward creaming (1). Because of the immiscible nature of the oil/water system, the poorly understood mechanisms of oil release are intrinsically different than those from hexane extraction processes.…”

“…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.…”

A novel process for the aqueous extraction of oil from <i>Camellia oleifera</i> seed and its antioxidant activity

“…Moreover, the emission of volatile n-hexane into the atmosphere contributes to the formation of ozone. In light of these considerations, the vegetable oil industry is actively looking for an alternative process (Fang et al, 2009;Moura et al, 2008;.…”

Aqueous Extraction and Nutraceuticals Content of Oil Using Industrial Enzymes from Microwave Puffing-pretreated <i>Camellia oleifera</i> Seed Powder

“…Enzyme-assisted aqueous extraction processing (EAEP) of extruded flakes yielded the highest oil yield, which were 96% for soybean (De Moura, et al, 2008;Wu, et al, 2009). Aqueous enzymatic process assisted by microwave extraction of oil from yellow horn seed kernels yielded the maximal oil yield of 55.8% under optimal conditions ).…”