Comparative study of high hydrostatic pressure and high temperature short time processing on quality of clear and cloudy Se-enriched kiwifruit juices

摘要

Selenium (Se) distribution was investigated and a comparative study was carried out into the effects of high hydrostatic pressure (HHP) and high temperature short time (HTST) treatments on quality for both clear and cloudy Se-enriched kiwifruit juice (clear-SKJ, cloudy-SKJ). Organic Se which accounted for 62.32% has a wider distribution than inorganic Se in kiwifruits and mainly comprising Se-protein and Se-polysaccharide. The process of separating kiwifruit pomace from juice caused significant decline in Se content with 43.07% and 49.04% in cloudy and clear juices respectively, and the sterilization process of HHP and HTST significantly decreased the Se contents from 50.46 +/- 0.42 mu g/kg to 39.63 +/- 0.51 mu g/kg and 37.93 +/- 0.08 mu g/kg in cloudy-SKJ, respectively. During the storage period, HTST- and HHP-processed juices showed no significant differences in total Se content, and similarly for certain chemical-physical qualities of total soluble solids, titratable acid, viscosity and pH. In addition, HHP (500 MPa/10 min) and HTST (110 degrees C/8.6 s) treatments inactivated yeasts and molds (Y&M) completely and sustained total aerobic bacteria (TAB) counts below 2.0 Log(10) CFU/mL which guaranteed the microbiological safety in clear-SKJ during storage at 4 degrees C and 25 degrees C for 42 days, but TAB counts were detected & 2.0 Log(10) CFU/mL which demonstrated a shorter shelf life in cloudy-SKI under the same storage conditions. Moreover, the HHP-treated sample showed better quality characteristics compared with the HTST-treated sample during 42-day storage except for total phenols and the storage time at 4 degrees C was more conducive to the preservation of the juices after HHP and HTST treatments.