Challenging chemical and quality changes of supercritical Co2 dried apple during long-term storage

The aim of this study was to analyze the stability of sensory properties and secondary metabolites in supercritical-CO2 (scCO2) dried ‘Elstar’ apple cuts/snacks during twelve months of storage at ‘room’ temperature. Air-drying and freeze-drying were used as reference methods. ScCO2-dried apple packed in aluminum-polyethylene bags under nitrogen gas retained a high sensory and nutritional quality, and acceptance level until the end of the observed period. The overall acceptance scores of these apples after 6 and 12 months of storage remained in the range of neutral consumer attitude “neither like nor dislike”. Packaging under nitrogen gas preserved the content of flavonols (≥0.14 g/kg), dihydrochalcones (≥0.10 g/kg), hydroxycinnamic acids (≥0.18 g/kg), triterpenes (≥5.72 g/kg), and proanthocyanidins (≥0.08 g/kg) in dried apple irrespective of the drying method applied. The comparison with the conventional drying processes demonstrated that scCO2-drying represents a promising alternative technology for the production of dried apple snacks. The study was assisted by the evaluation of consumer attitudes towards dried fruit and drying technologies. Freeze-drying, air-drying and scCO2-drying were recognized by the tested consumers as trustful drying-processes, with expressed interests in buying scCO2-dried products if the technology was scientifically proven as excellent in preserving nutrients, color and taste of food products.