Preparation of rapeseed protein by enzymatic hydrolysis assisted alkaline water extraction and its nutritional value in comparison with rapeseed meal and soybean protein concentrate

The global shortage of soybean protein resources necessitates the development of alternative and sustainable plant protein sources. Rapeseed is the second largest crop planted in the world. However, rapeseed protein (RP) is mainly used as animal feed; further research is required to explore its potential as a human food protein source. This experiment was conducted to develop a novel method to prepare RP from rapeseed meal (RSM), analyze its physicochemical properties, and evaluate its nutritional value as a human food protein source. RSM and soybean protein concentrate (SPC) were used for comparisons. Compared to RSM and SPC, RP exhibited higher protein solubility, protein dispersibility, and acid–soluble protein, sweetness, saltiness, umami materials, and lower crude fiber and protein molecular weight. Meanwhile, RP demonstrated superior oil holding capacity, swelling capacity, and higher contents of reducing sugar and soluble sugar compared to SPC ( P < 0.05). The α–helix content and the ratio of α–helix/β–sheet in RP were lower than those in SPC ( P < 0.05). RP also showed higher in vitro and in vivo protein digestibility than RSM and was comparable to SPC. Furthermore, RP contained the rich bioactive peptides that are associated with angiotensin–converting enzyme inhibitory activity and anti–oxidant properties. In conclusion, RP is a relatively high–quality new sustainable protein source with significant potential for development and utilization value in human food. However, the preparation method of RP must be further optimized to provide higher purity RP and provide liquid RP, thereby reducing costs. • A novel technology for the preparation of rapeseed protein (RP) was developed. • RP exhibited higher crude protein, protein solubility and digestibility. • RP demonstrated superior physicochemical properties on food. • RP contained rich bioactive peptides. • RP can as a sustainable source of protein in human diets.