College of Food and Biochemical Engineering, Guangxi Science & Technology Normal University, Laibin 546199, China.
Molecules. 2024 Jun 2;29(11):2613. doi: 10.3390/molecules29112613.
Recovering valuable active substances from the by-products of agricultural processing is a crucial concern for scientific researchers. This paper focuses on the enrichment of soybean trypsin inhibitor (STI) from soybean whey wastewater using either ammonium sulfate salting or ethanol precipitation, and discusses their physicochemical properties. The results show that at a 60% ethanol content, the yield of STI was 3.983 mg/mL, whereas the yield was 3.833 mg/mL at 60% ammonium sulfate saturation. The inhibitory activity of STI obtained by ammonium sulfate salting out (A-STI) was higher than that obtained by ethanol precipitation (E-STI). A-STI exhibited better solubility than E-STI at specific temperatures and pH levels, as confirmed by turbidity and surface hydrophobicity measurements. Thermal characterization revealed that both A-STI and E-STI showed thermal transition temperatures above 90 °C. Scanning electron microscopy demonstrated that A-STI had a smooth surface with fewer pores, while E-STI had a rough surface with more pores. In conclusion, there was no significant difference in the yield of A-STI and E-STI ( < 0.05); however, the physicochemical properties of A-STI were superior to those of E-STI, making it more suitable for further processing and utilization. This study provides a theoretical reference for the enrichment of STI from soybean whey wastewater.
从农产品加工副产物中回收有价值的活性物质是科学研究人员关注的焦点。本文主要研究了利用硫酸铵盐析或乙醇沉淀从大豆乳清废水中富集大豆胰蛋白酶抑制剂（STI）的方法，并对其理化性质进行了讨论。结果表明，在 60%乙醇含量下，STI 的产率为 3.983mg/mL，而在 60%硫酸铵饱和度下，STI 的产率为 3.833mg/mL。硫酸铵盐析（A-STI）得到的 STI 的抑制活性高于乙醇沉淀（E-STI）得到的 STI。通过浊度和表面疏水性测量证实，A-STI 在特定温度和 pH 值下的溶解度优于 E-STI。热特性表明，A-STI 和 E-STI 的热转变温度均高于 90°C。扫描电子显微镜表明，A-STI 表面光滑，孔隙较少，而 E-STI 表面粗糙，孔隙较多。综上所述，A-STI 和 E-STI 的产率无显著差异（<0.05）；然而，A-STI 的理化性质优于 E-STI，更适合进一步加工和利用。本研究为从大豆乳清废水中富集 STI 提供了理论参考。
