Loman Abdullah Al, Islam S M Mahfuzul, Li Qian, Ju Lu-Kwang
Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325-3906, USA.
Bioprocess Biosyst Eng. 2016 Oct;39(10):1501-14. doi: 10.1007/s00449-016-1626-5. Epub 2016 May 20.
Soybean carbohydrate is often found to limit the use of protein in soy flour as food and animal feed due to its indigestibility to monogastric animal. In the current study, an enzymatic process was developed to produce not only soy protein concentrate and soy protein isolate without indigestible carbohydrate but also soluble reducing sugar as potential fermentation feedstock. For increasing protein content in the product and maximizing protein recovery, the process was optimized to include the following steps: hydrolysis of soy flour using an Aspergillus niger enzyme system; separation of the solid and liquid by centrifugation (10 min at 7500×g); an optional step of washing to remove entrapped hydrolysate from the protein-rich wet solid stream by ethanol (at an ethanol-to-wet-solid ratio (v/w) of 10, resulting in a liquid phase of approximately 60 % ethanol); and a final precipitation of residual protein from the sugar-rich liquid stream by heat treatment (30 min at 95 °C). Starting from 100 g soy flour, this process would produce approximately 54 g soy protein concentrate with 70 % protein (or, including the optional solid wash, 43 g with 80 % protein), 9 g soy protein isolate with 89 % protein, and 280 ml syrup of 60 g/l reducing sugar. The amino acid composition of the soy protein concentrate produced was comparable to that of the starting soy flour. Enzymes produced by three fungal species, A. niger, Trichoderma reesei, and Aspergillus aculeatus, were also evaluated for effectiveness to use in this process.
由于单胃动物难以消化大豆碳水化合物，大豆碳水化合物常被认为会限制大豆粉作为食品和动物饲料时蛋白质的利用。在本研究中，开发了一种酶法工艺，不仅可生产不含难消化碳水化合物的大豆浓缩蛋白和大豆分离蛋白，还能生产作为潜在发酵原料的可溶性还原糖。为提高产品中的蛋白质含量并使蛋白质回收率最大化，该工艺经过优化，包括以下步骤：使用黑曲霉酶系统水解大豆粉；通过离心（7500×g 离心 10 分钟）分离固液；一个可选步骤，用乙醇（乙醇与湿固体的比例（v/w）为 10，得到约 60%乙醇的液相）从富含蛋白质的湿固体流中洗涤去除截留的水解产物；以及通过热处理（95°C 处理 30 分钟）从富含糖的液体流中最终沉淀残留蛋白质。从 100 克大豆粉开始，该工艺可生产约 54 克蛋白质含量为 70%的大豆浓缩蛋白（或者，包括可选的固体洗涤步骤，则为 43 克蛋白质含量为 80%的大豆浓缩蛋白）、9 克蛋白质含量为 89%的大豆分离蛋白以及 280 毫升还原糖含量为 60 克/升的糖浆。所生产的大豆浓缩蛋白的氨基酸组成与起始大豆粉相当。还评估了黑曲霉、里氏木霉和棘孢曲霉这三种真菌产生的酶在该工艺中的有效性。
