Chlorella vulgaris Protein Isolate Effectively Protects Lacticaseibacillus rhamnosus GG Viability During processing, Storage, and In vitro Digestion

This study examined the protective effect of Chlorella vulgaris protein isolate (CPI) on the biological activity of Lacticaseibacillus rhamnosus GG (LGG) during lyophilisation, storage, and in vitro digestion. Prior to lyophilisation, probiotic hydrogels were either fermented to pH 4.5 (CF) or left untreated (CNT). The microstructure, physicochemical, and thermal properties of the resulting probiotic powders were analysed, along with LGG adhesion to an in vitro intestinal epithelium model. Embedment in CPI-based matrices provided effective lyoprotection, with CNT offering greater stability than CF. Elevated storage temperatures and relative humidity (RH) accelerated LGG inactivation, particularly in CF. While a sufficient proportion of LGG survived the harsh conditions during in vitro digestion, pre-fermentation had a negligible impact. Additionally, a satisfactory level of LGG adhesion to the intestinal mucus layer was observed. Overall, CPI exhibits strong stabilizing properties for LGG viability and represents a promising plant-based alternative to dairy proteins for probiotic food formulations.