Impact of atmospheric cold plasma on digestibility, structural integrity, functional properties, and safety of protein isolate from Chlorella vulgaris

Microalgae are an emerging, nutrient-rich and sustainable protein source to meet the growing global demand. However, their food applications have been impeded by several factors, like inferior functional properties and presence of allergens and anti-nutritional factors, etc. In this study, atmospheric cold plasma (ACP) generated at different input voltages (140, 160, and 200 V ) was applied to treat protein isolated from Chlorella vulgaris for 5, 10 and 20 min, and its effects on structural changes, protein digestibility, allergenicity, and functional properties were evaluated. Moderate ACP treatments (140 V -20 min and 160 V -5 min) were found to be the optimum conditions as they increased the content of essential amino acids and resulted in the highest level of protein digestibility (0.99–1). However, increasing the treatment intensity could cause protein degradation and reduce its digestibility. The treatment of 200 V -5 min unfolded protein structure and modified amino acid side chains, resulting in increased protein surface hydrophobicity from 215 to 228 a.u. Additionally, proper ACP treatments enhanced protein's water holding capacity by 11%, emulsifying activity by 27%, and foaming expansion by 12%, decrease its antinutritional factors, including trypsin inhibitors, tannins, and phytic acid by 57%, 36% and 66%, respectively, and reduced its predicted allergenic potential by 51%. These findings proved ACP as an effective technology to facilitate the development of new, safe, and nutritious ingredients for the food and nutraceutical industries.