Effects of supercritical carbon dioxide and thermal treatment on the inulin chemical stability and functional properties of prebiotic-enriched apple juice

Inulin-enriched apple juice was subjected to supercritical CO₂ processing under different pressure levels (10, 15, and 20 MPa at 35 °C, 10 min and a 67% CO₂ volume ratio) and to conventional thermal treatment (95 °C/1 min). Physicochemical properties (pH, soluble solid content, ζ-potential, particle size distribution and rheological behavior), organic acid (citric and malic) content, and phenolic compounds (UHPLC-ESI-MS/MS) were evaluated; moreover, antioxidant activity assays (DPPH and TEAC) as well as sugar content and fructo-oligosaccharide analyses (HPAEC-PAD) were performed. The increase in pressure levels reduced the particle size suspended in the functional juice. Supercritical processing was able to preserve all compounds responsible for the functional properties of the beverage as well as the natural nutritional components such as sorbitol, glucose, fructose and sucrose. The emerging technology did not reduce the antioxidant activity of the juice samples, thus maintaining their functionality. The inulin chemical profile was not altered by the supercritical CO₂ processing, while in the thermally treated sample, there was a breakdown of the inulin chain into units of short-chain fructo-oligosaccharides. Overall, supercritical technology may be an interesting option for inulin-enriched apple juice processing.