采用超滤法回收水解液中的蛋白质,在单因素试验的基础上,通过Box-Behnken响应面法试验设计建立了操作压力、溶液质量分数、溶液pH值对膜通量影响的模型.研究结果表明,各因素对膜通量的影响由大到小依次为溶液质量分数、操作压力、溶液pH值.经优化得到的最佳工艺参数为:操作压力0.20 MPa、溶液质量分数5.60％、溶液pH值8.50.在此条件下超滤膜通量为7.02 L/(m2·h),回收物中蛋白质质量分数增至88.63％,红外光谱显示构成大豆蛋白的各官能团特征峰明显,高效液相色谱结果显示超滤对水解液中低聚糖类物质的脱除效果较好,所回收蛋白在功能特性上溶解性得到提升,且在酸性pH值范围内有明显改善,而乳化活性指数和乳化稳定性指数有所降低.超滤法回收水解液蛋白可实现同步浓缩与杂质分离,为水解液的增值利用提供了可行方法.%Enzyme-assisted aqueous extraction processing (EAEP) has long been considered as a promising alternative to traditional solvent oil extraction,which has gained increasing attention recently.After EAEP of soybeans,three distinct layers are formed:cream,skim and residual fraction.The skim fraction contains substantial amount of protein as well as oil,sugar and other impurities.In order to recover value from this liquid fraction,ultrafiltration was employed for protein concentration and isolation.To investigate the interrelationship between operating parameters and membrane flux,BoxBehnken response surface methodology was introduced.The results indicated that the three factors'effects on membrane flux followed the decreasing order as:solution mass fraction,transmembrane pressure and solution pH value.The improved regression model was fitted with determination coefficient of 0.997 5 and optimal factors were as follows:operative pressure of 0.20 MPa,solution mass fraction of 5.60％,and solution pH value of 8.50.The permeate flux under above conditions was 7.02 L/(m2·h) and protein purity was increased to 88.63％.The infrared spectrum and HPLC analysis showed evidently characteristic peaks of functional groups in soybean protein and remarkable low levels of undigestible oligosaccharides.Besides,the protein extracted from EAEP showed improved solubilities especially at acidic pH value,but it slightly decreased emulsifying activity index and emulsifying stability index.Further improvement can be achieved if industrial fractionation unit was employed and process optimization was conducted.A complete cost-effectiveness analysis would also need to be done to estimate the economic viability of this application.
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