Chitinase-primed ultrasound enhances Saccharomyces cerevisiae cell-wall deconstruction and yeast-protein remodelling in two complementary model systems.

Yeast protein is a promising sustainable food ingredient. Still, its wider use in high-protein emulsified and aerated foods is constrained by incomplete recovery from yeast biomass and limited techno-functionality of yeast-protein ingredients. This study investigated whether chitin-associated wall architecture can be treated as a process-relevant structural constraint in yeast biomass and whether sequential chitinase→ultrasound treatment can independently remodel the structure and functionality of a yeast-protein ingredient. Two independent but complementary yeast-derived model systems were used: NY503 Saccharomyces cerevisiae biomass was employed to evaluate cell-wall deconstruction and protein recovery, while F80 yeast protein was used to assess structural, colloidal, and interfacial remodelling. F80 was not obtained from the NY503 soluble extract. Compared with the untreated control, sequential chitinase→ultrasound treatment increased soluble protein release from 3.40 to 30.38 mg/mL, total soluble solids from 3.3 to 14.0°Brix, and soluble yeast extract recovery from 33.55 to 137.15 mg/mL, while reducing cell viability from 7.55 to 2.05 log CFU/mL and residual pellet mass from 125.5 to 22.3 mg/mL. Residual chitin, normalized to the initial dry-biomass loading, decreased from 6.94 to 0.24 g GlcNAc equivalents/100 g initial dry biomass, and FTIR, compositional, kinetic, and SEM analyses confirmed extensive remodelling and fragmentation of the wall-rich residual fraction. In the independent F80 model, the same sequential treatment reorganized hydrogen bonding and protein-polysaccharide interactions, promoted β-sheet-enriched conformational remodelling, increased surface hydrophobicity and free sulfhydryl exposure, and reduced disulphide-linked aggregation. These molecular changes improved solubility from 34.50% to 62.03%, reduced particle size from 254.23 to 158.10 nm, and shifted ζ-potential from -18.83 to -26.30 mV. Consequently, emulsifying activity, emulsion stability, foaming ability, and foam stability increased to 91.27 m2/g, 37.43 min, 162.17%, and 98.60%, respectively. Together, these complementary models show that sequential chitinase→ultrasound processing can enhance protein recovery from intact yeast biomass and independently improve the colloidal and interfacial functionality of a yeast-protein ingredient.