High‐pressure processing at increased temperatures provides enhanced removal of indigenous microbial contamination in beet/carrot juice without damaging the bioactive components

Abstract

SummaryIn this study, an optimised high hydrostatic pressure process (600 MPa, 15 min, 55 and 65 °C) caused elimination of microbial levels in beetroot/carrot juice (80:20 v/v, pH 4.0) after 28 days of storage (4 °C) (psychrotrophic bacteria, yeast and mould counts below the limit of detection = 0 log cfu mL−1). Room temperature (20 °C) was insufficient for the complete elimination of psychrotrophic bacteria (0.9–2.0 log cfu mL−1 after 7–28 days of storage). No significant (P < 0.05) changes in the polyphenol content were observed (1.11 ± 0.13 in control vs. 1.13 ± 0.13 mg gallic acid mL−1 in samples treated at 65 °C). No significant (P < 0.05) changes in the antioxidant, antiradical activity and biological properties of the high‐pressure processing (HPP)‐treated juice were observed in the studies involving CCD 841 CoTr and HT29 cell lines. The HPLC‐MS analysis confirmed increase in isobetalain, decarboxybetalain and betalain content (by 100%, 14% and 10%) and loss of vulgaxanthin I (by 65%) after HPP at 65 °C. The innovative character of this paper stems from the comprehensive quality assessment (especially experiments involving cell lines) of high‐quality, safe beetroot–carrot juice that retains a major part of its bioactive compounds.