Ultrasound-assisted enzymatic digestion for efficient extraction of proteins from quinoa
Chao Yang, Wenyu Liu, Xijin Zhu, Xuejian Zhang, Yuming Wei, Jie Huang, Farong Yang, Farong Yang, Fumin Yang, Fumin Yang
Abstract
This study aimed to investigate the potential synergistic impact of ultrasound and enzyme on the extraction of quinoa protein, to enhance its extraction yield and modify its functional properties. The highest protein extraction rate (26.72 %) was achieved under the following conditions: power, 400 W; time, 210 min; pH, 10.0; temperature, 50 °C; and amount of alkaline proteinase, 1.668 kat. The ultrasound process, due to its elevated shear, mechanical energy, and cavitation, enhanced the solubility of the substrate, rendering it more easily accessible to the enzyme. Consequently, this acceleration of the chemical reaction resulted in an improved protein yield. The optimized conditions of ultrasound-assisted enzymatic treatment effectively induced alterations in the structure of quinoa protein. The findings from the analysis of surface hydrophobicity, particle sizes, sulfhydryl content, fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy collectively demonstrated the unfolding of protein molecules and the exposure of hydrophobic and sulfhydryl groups following treatment. Additionally, compared to single ultrasound and non-ultrasound procedures, the protein produced by this process had higher solubility (86.40 %), higher emulsifying activity (100.44 m2/g), better foaming capacity (122.45 %), superior water/oil-binding capacity. Hence, the ultrasound-assisted enzymatic method exhibits potential as a suitable technique for enhancing both the quantity and quality of quinoa protein. Furthermore, this study contributes to the establishment of a theoretical framework for the incorporation of quinoa protein within the realm of food processing.