Functional characterisation of traditional Andean freeze-sun dried potato derivatives, Chuño and Tunta: Resistant starch, probiotic fermentation, and production of SCFA and GABA as bioactive metabolites

Chuño (black) and tunta (white) are two ancient potato derivatives traditionally produced in the high-altitude Andean region through a natural freezing, pressing, washing, and sun-drying process that preserves the tubers for long-term storage. The present study investigates the resistant starch (RS) content, antioxidant capacity, and bioactive metabolites produced by fermentation with probiotic bacteria. The RS content in dry matter chuño (52.63 g/100 g) and tunta (46.39 g/100 g) was found to be higher than that in native potatoes (36.66 g/100 g). The fermentation with Lacticaseibacillus rhamnosus, Lacticaseibacillus casei, Levilactobacillus brevis, and Propionibacterium freudenreichii resulted in the production of γ-aminobutyric acid (GABA) and short-chain fatty acids (SCFAs). Fermented chuño produced higher levels of SCFA and GABA. These properties provide an additional functional property to chuño, which also has an interesting amino acid profile and protein content. These findings establish a foundation for incorporating Andean potato derivatives into functional food formulations.