Biotransformation approaches using solid-state fermentation and germination with high-intensity ultrasound to produce added-value hemp protein nanoaggregates

Hemp protein, with superior nutritional content and high digestibility, has attracted significant interest in recent years. However, like other plant protein sources, hemp protein has still suffered from underutilization in industrial applications due to its poor solubility attributes. To overcome this limitation, this study aimed to use biotechnological approaches such as germination (1, 3, 5 days) and solid-state fermentation using Lactobacillus plantarum and Bacillus subtilis to enhance the physicochemical, functional, and bioactive properties of hemp protein. The high-intensity ultrasound combined with these treatments for further modifications. The protein recovery in the defatted flour increased by 42% in germinated isolates compared to the untreated isolate. The primary structure changes were proven by degrading high molecular weight proteins to lower weights in SDS-PAGE. The secondary and tertiary structure changes of isolates were observed in FTIR, CD spectra, DSC, and free SH groups. While the particle sizes of isolates were reduced by 83%, solubility increased by 133% in fermented and ultrasonicated isolates. Water, oil absorption capacities and emulsion activities were increased by 103%, 194%, and 300%, respectively, in modified isolates compared to the untreated isolate. Total phenolic and antioxidant activities of isolates improved in germinated and fermented isolates. Fermentation, germination, and ultrasonication are promising, green, safe, alternative biomodification techniques that may effectively improve protein functionality. These clean-labeled proteins can also be used as bioactive agents in the food industry.