Comparison of high hydrostatic pressure and high temperature short time processing on quality of purple sweet potato nectar

High hydrostatic pressure (HHP) (400 MPa/10 min, 500 MPa/5 min, 600 MPa/2.5 min) and high temperature short time (HTST) (110 degrees C/8.6 s) processing of purple sweet potato nectar (PSPN) were comparatively evaluated by examining their impacts on microorganisms, total phenols and anthocyanins, antioxidant capacity, color and shelf life prediction during 12 weeks of storage at 4 and 25 degrees C. Yeasts and molds (Y&M) were not detected, and the counts of total aerobic bacteria (TAB) were less than 1.59 log(10)CFU/mL during storage at 4 and 25 degrees C. All quality parameters investigated experienced no significantly different impacts between the two pasteurization techniques, except anthocyanins and antioxidant activity degradation during storage at 25 degrees C, where the decrease was dependent on the specific treatments that were applied. The samples stored at 4 degrees C showed better quality and longer shelf life when compared with those stored at 25 degrees C. A longer shelf life was observed in HHP-treated samples compared to HTST-treated ones. Industrial relevance: This research paper presents a fair comparison of HHP and HTST processed purple sweet potato nectar, which could provide information of storage stability in microorganisms, specific known nutrients, undesired changes and other quality-related aspects. The available data are provided for the evaluation and application of HHP or HTST in the juice industry, and criteria for commercial production of high quality purple sweet potato nectar with safety requirements could be established. (C) 2012 Elsevier Ltd. All rights reserved.