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Enzyme Processing of Soy Flour with Minimized Protein Loss
Author(s) -
Islam S. M. Mahfuzul,
Loman Abdullah A.,
Li Qian,
Ju LuKwang
Publication year - 2020
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1002/aocs.12396
Subject(s) - soy protein , chemistry , protease , proteolysis , enzyme , hydrolysate , chromatography , monosaccharide , neutral protease , food science , ionic strength , carbohydrate , proteolytic enzymes , biochemistry , hydrolysis , organic chemistry , aqueous solution
The enzymatic treatment of defatted soy flour (SF) to reduce indigestible carbohydrates can result in undesirable protein loss. Here protein loss was minimized with quantitation of the effects of ionic strength (IS), protease activity, and SF toasting. At the enzyme processing condition (25% w/v SF, 50 °C, pH 4.8, 48 hours), protein loss increased linearly with the IS in enzyme broths (EB); e.g., contacting untoasted SF with water or heat‐deactivated EB showed protein loss of 28% in water but up to 40% when IS was increased in the range of 0.04–0.19 M. Protein loss also increased with protease in EB (nondeactivated): after adjusted for IS‐related loss, approximately 10% and 25% additional protein loss occurred in EB of 73 and 490–557 U/(g SF) protease, respectively. SDS‐PAGE results showed that proteolysis was not extensive, mainly on β‐conglycinin α'/α and glycinin acidic 37‐kDa subunits; and most of the proteolytic products could be recovered by heat‐induced precipitation. SF toasting effects were studied, particularly at 2‐hours 160°C, with material balances, protein distributions, and monosaccharide yields in hydrolysates. Overall, protein loss was minimized to 5.2% and the conversion of carbohydrate to monomeric sugars increased to 89.2%.