Potential of high-pressure processing and high-temperature/short-time thermal processing on microbial, physicochemical and sensory assurance of clear cucumber juice

Abstract

Clear cucumber juice, clarified by ultra-filtration (UF), was treated by high-pressure processing (HPP, 500 MPa/5 min) and high-temperature/short-time thermal processing (HTST, 110 °C/8.6 s), and stored at 4 °C. UF significantly decreased total aerobic bacteria (TAB) and yeasts and molds (Y&M) in the juice by 1.35 ± 0.11 and 1.94 ± 0.02 log cycles, respectively, increased juice clarity to 99.85 ± 0.07%, and did not change pH, titrable acidity (TA) and four key aroma compounds of (Z)-6-nonenal, (E,Z)-2,6-nonadienal, (E)-2-nonenal, and (E,Z)-3,6-nonadien-1-ol. Following the UF, TAB and Y&M in the juice were reduced by HPP or HTST to be < 1 log cycle, and showed no outgrowth after refrigerated storage of 20 days. HPP-treated juice showed less total color change, higher clarity and retained more key aroma compounds than HTST-treated juice. Moreover, sensory evaluation suggested that HPP-treated juice always showed higher scores for overall acceptability than HTST-treated juice. The combination of HPP and refrigeration could be used as an alternative to produce high quality clear cucumber juice with a shelf-life of 20 days. Industrial relevance Consumption of fresh vegetable juices, as a low-sugar and calorie alternative to fruit juices, is becoming increasingly popular. The objective of this work is to use ultra-filtration membrane to develop clear cucumber juice, which are not commercially available on the market in China. And further to explore the possibility of high pressure processing (HPP) plus refrigeration on quality assurance of clear cucumber juice. Findings of this study could help processors commercialize this technology in developing clear fruit and vegetable juices using non-thermal processing to replace current thermal processing.