Metabolome profiling and sensory analysis revealed the seafood flavor enhancement in the treated biomass powder of golden Auxenochlorella pyrenoidosa mutant strain by high-pressure homogenization

As a novel resource of algae-based alternatives protein, the golden biomass of Auxenochlorella pyrenoidosa mutant (CX41 strain) was prepared by fermentation in shake flasks, following high-pressure homogenization (HPH) for cell disruption. The preferred parameters were obtained with 50 % (wet w/v, wet weight/volume) of CX41 biomass under 950 bars for HPH treatment in a single pass. Surprisingly, the enhanced pleasant flavor was observed in CX41 powder after HPH treatment (HPH-CX41). Electronic tongue and odor sensory analyses revealed significant increases of 15.22 % for the umami and 27.59 % for shredded squid odor in HPH-CX41 than that of CX41 powder. Profiling of non-volatiles verified significant increase of free amino acids content in HPH-CX41 powder. The amino acids and oligopeptides like glutamic acid and arginine-leucine increased by 4.56 and 16.07 folds respectively, resulting in a significant increase in umami. Analysis of volatiles and their relative odor activities indicated that the dominant odor in both powders was roasted, attributed to furans and pyrazines like 2-methyl-3-furanthiol, 5-methyl-2-furanmethanethiol, and 2, 3-diethyl-5-methyl-pyrazine. Their increased contents in HPH-CX41 powder resulted in an increased roasted intensity. The relative odor activity value (rOAV) of 2-pentyl-furan, with pleasant aroma of squid, significantly increased, leading to the enhanced seafood flavor of HPH-CX41 powder. This is the first report to investigate the metabolite basis of flavor enhancement in Auxenochlorella pyrenoidosa biomass powder by HPH technology, providing a potential application of HPH-CX41 powder as novel high-protein and flavoring agent in microalgae-based seafood substitutes.