Alpha-amylase-assisted extraction of protein concentrates from Raphanus sativus L. leaves

This research focused on the preparation of radish leaf protein concentrates (RLPC) by applying enzyme-assisted extraction, where alpha-amylase, protease, and xylanase were employed for the same. The alpha-amylase-assisted extraction showed maximum extraction yield (10.22%) and protein content (66.93%). Therefore, this method was optimized using response surface methodology where optimized conditions of extraction temperature (42.8 degrees C), amylase concentration (18,446 U), and extraction time (4.44 h) resulted in an extraction yield of 9.56% and protein content of 89.41% in the extracted RLPC. Fractionation of the protein concentrate demonstrated the maximum presence of glutelins followed by prolamine, albumins, and globulins. The apparent molecular weights of the RLPC and its isolated fractions ranged between 35 and 92 kDa. The RLPC showed a high in vitro protein digestibility (92.17%), considerable antioxidant activity (DPPH, FRAP, ABTS), and desirable structural and functional properties (water and oil holding capacity, emulsion capacity and stability, least gelation concentration, etc.). Threonine, methionine, and tryptophan were found to be the most abundant amino acids present in the RLPC. The microbial load of the stored RLPC was observed to be in acceptable range during 6 weeks of storage under ambient and refrigerated temperature conditions. Conclusively, alpha-amylase-extracted RLPC serves as a potential alternative edible plant-based protein fortification source for various food formulations.

Automated summary

This research focused on the preparation of radish leaf protein concentrates (RLPC) using enzyme-assisted extraction. The optimized extraction method showed high protein content and desirable functional properties. The RLPC exhibits excellent antioxidant activity and can serve as a potential alternative protein source for various food formulations.