Protein recovery from enzyme‐assisted aqueous extraction of soybean

Abstract

Enzyme-assisted aqueous oil extraction from soybean is a "green" alternative to hexane extraction that must realize potential revenues from a value-added protein co-product. Three technologies were investigated to recover protein from the skim fraction of an aqueous extraction process. Ultrafiltration achieved overall protein yields between 60% and 64%, with solids protein content of 70%, and was effective in reducing stachyose content, with fluxes between 4 and 10 L/m(2) hr. Protein content was limited because of high retention of lipids and the loss of polypeptides below 13.6 kDa. Isoelectric precipitation was effective in recovering the minimally hydrolyzed proteins of skim, with a protein content of 70%, again limited by lipid content. However, protein recovery was only 30% because of the greater solubility of the hydrolyzed proteins. Recovery by the alternative of protein capture on dextran-grafted agarose quaternary-amine expanded bed adsorption resins decreased with decreasing polypeptide molecular weight. Proteins with molecular mass greater than 30 kDa exhibited slow adsorption rates. Expanded bed adsorption was most effective for recovery of proteins with molecular weight between 30 and 12 kDa. Overall, adsorption protein yields were between 14% and 17%.

Soy protein recovery in a solvent‐free process using continuous liquid–solid circulating fluidized bed ion exchanger

“…The two eluant types investigated in this study were NaCl and KI. From previous literature and manufacturers' suggestions, NaCl was the eluant type of choice 2, 11, 12…”

“…SPC contain no less than 70% and SPI contain no less than 90% protein on a dry basis, although they may be marketed on an as‐is basis. A multitude of different molecular properties are expressed by SPI that is comprised a multifaceted mixture of proteins that range in size from 200 to 600 kDa 2…”

Extracting Protein from Antarctic Krill (Euphausia superba)

“…ISP technology has been applied broadly to many products because of its convenience, simplicity, the high quality of recovered proteins, A c c e p t e d M a n u s c r i p t 3 low-cost and high protein recovery yield [8,9,10] , and has been applied more widely in food biotechnology field in recent years [2,6,11,12] . For Antarctic krill, the published protein recovery yield using ISP process is low at about 59% of total available protein [7] .…”

Recovery of high value‐added protein from enzyme‐assisted aqueous extraction (EAE) of soybeans by dead‐end ultrafiltration

“…It was estimated that almost 27 L of SF was produced for every liter of soybean oil extracted (Yao, Wang, & Wang, 2011). However, since the solubility of hydrolyzed protein was significantly enhanced at acidic pH, isoelectric precipitation only resulted in a total protein recovery of 30% in extracting skim protein from EAE of soybeans (Campbell & Glatz, 2010). Conventional methods for high-purity soybean protein extraction are mainly based on their low solubility at average isoelectric point (pH 4.5) (Alibhai, Mondor, Moresoli, Ippersiel, & Lamarche, 2006).…”

“…However, to our knowledge, only two studies have previously utilized UF to recover skim protein from EAE of soybeans (Campbell & Glatz, 2010;de Moura, Campbell, de Almeida, Glatz, & Johnson, 2011), and only Protex 6L was applied for enzymatic hydrolysis. However, information on the performance of UF to recover skim protein extracted with different proteases is still unknown.…”