Application of supercritical carbon dioxide for the preservation of strawberry juice: Microbial and physicochemical quality, enzymatic activity and the degradation kinetics of anthocyanins during storage

摘要

Supercritical carbon dioxide (SCCD) was applied for strawberry juice preservation. SCCD under selected parameters was effective for microflora and enzyme inactivation. For storage studies samples preserved at 30 and 60 MPa, at 45 degrees C for 30 min were selected. Yeasts and moulds were not detected after SCCD treatment in these conditions, whereas TMC was similar to 1.7 log CFU/g. Polyphenol oxidases were inactivated, whereas peroxidases decreased by similar to 85%. SCCD treatment resulted in the hydrolysis of sucrose and similar to 30% losses of vitamin C, which was totally decomposed after the 4th week of storage. Anthocyanins were not affected by the SCCD process and the kinetic rate constant of degradation during storage ranged from 2.12 x 10(-2) to 3.10 x 10(-2) (days(-1)), and the half-time from 22.4 to 32.7 days, depending on the monomer and pressure applied. Overall, SCCD treatment seems to be a promising technique to obtain high quality strawberry juice as a safe alternative to non-pasteurized juices.