Quality Characteristics of Squeezed Yuzu (Citrus junos) Juice Subjected to Commercial Sterilization Technologies

Abstract

The objective of this study was to find the optimal commercial sterilization technology for squeezed yuzu (Citrus junos) juice by analyzing microbes, antioxidant activity, and physicochemical properties after commercial sterilization [LTLT (low temperature long time) at 60°C for 30 min, HTST (high temperature short time) at 75°C for 1 min, and HPP (high pressure processing) at 500 MPa for 3 min]. Juices were stored for 84 days at 4°C after sterilization, during which no microbes were detected. Juice pH was not a significant difference regardless of treatments, but significant differences were observed in °Brix and color values between HTST and LTLT treatments and HPP treatment due to the conversion of pectin into reducing sugars and carotenoid pigment changes during thermal treatments. HPP treatment resulted in 90% and 10% higher DPPH radical scavenging activity and total phenol contents, respectively, compared to HTST treatment, which was attributed to the destruction of phenol and vitamin C during thermal treatment. This study shows that HPP was the most effective sterilization technology because it effectively maintained antioxidant activity and physicochemical properties and extended the shelf life of squeezed yuzu juice. Furthermore, our results suggest HPP should be considered the sterilization technology of choice in the juice industry.