Analysis of water-soluble bioactive compounds in commonly consumed soymilk in China

Soybean, an important source of many bioactive compounds, is of interest because of the health benefits it confers. We compared the contents of different bioactive components, such as peptides, amino acids, isoflavones, saponins, and oligosaccharides, in five commonly used soymilk types in China, using an amino acid analyzer, high-performance liquid chromatography, and an ultraviolet spectrophotometer. The concentrations of almost all bioactive compounds, except for stachyose and raffinose, were significantly higher in homemade soymilk (HSM) samples than in ready-made soymilk (RSM) samples. HSM created using non-genetically modified soybeans contained the most amino acids (21.7%), water-soluble proteins (25.6%), peptides (11.90%), and water-soluble isoflavones (1175 mu g/mL). HSM made using genetically modified soybeans contained the most saponin (36.7 mg/mL). RSM samples contained the most stachyose and raffinose. These findings provide basic information for evaluating the function of soymilk with regard to its bioactive ingredients. (C) 2015 Elsevier Inc. All rights reserved.