Enzymatic activity, browning, physiochemical and phenolic evaluation of fruit juices subjected to high pressure-CO₂ processing at different temperatures

Abstract

The traditional thermal processing of the fruit juices exhibited several disadvantages related to nutrients and quality loss. Thus, in order to get the full nutritional characteristics, there is a need to investigate the processing techniques which can maintain the quality of fruit juices. In this study the effect of high pressure carbon dioxide (HP-CO₂) at different temperatures (20, 30, 40, 50, 60 and 70 ºC), an emerging juice processing treatment was investigated on the physiochemical properties, enzymatic activity and phenolic profile of peach, apple and pear juices. For comparison, the juices were also subjected to the thermal treatment at the same temperatures. Results showed that HP-CO₂ caused significantly higher decline in pH, total soluble solids (TSS) and increase total color difference (ΔE) value then thermally treated juices. Because of having lower pH and other factors, comparing to thermal treatment, the HP-CO₂ treated juices exhibited significantly lower relative enzymatic activity which caused lower relative browning degree of the juices. The phenolic compounds were slightly decline by HP-CO₂ treatments. Generally, increase in temperature resulted in decrease in pH, TSS, enzymatic activity and increase in ΔE value. It is concluded that HP-CO₂ juice processing technique can be used effectively for processing the fruit juices with quality attributes.