Effects of Processing Treatments on the Bioactive Compounds of Campbell Grape Juice

It is well known that phenolic compounds and flavonoids have a lot of health benefits. Most current heat treatments especially those that are using too high temperature and longer period of processing produce juice with unacceptable analytical and sensory properties. Thus, microwave heating, ultrasonication and blanching before grape juice processing were employed in this study. Each juice sample was subjected to total phenolics, total flavonoid, total anthocyanin and % radical scavenging activity analysis. Analysis of Variance and Duncan’s multiple range tests were performed using the SAS program. The concentration of total phenolics, total flavonoids, total anthocyanin and % radical scavenging activity of the grape juices treated with microwave heating and ultrasonication increased significantly with increasing treatment time notably at 5 min treatment. It can be noted that all the bioactive contents and % radical scavenging activity were higher in non- cold stabilized grape juice than in cold stabilized juices. However, blanching whole grapes for longer period of time before processing resulted in the decrease of all bioactive compounds and % radical scavenging activity both in non-cold stabilized and cold stabilized juice especially at 5 min blanching period. It was also showed that 1 min blanching is more effective in increasing the bioactive compounds of the grape juice as compared to other treatment time.

Keywords: Campbell grape, Grape juice, Total phenolics, Flavonoid, Anthocyanin, Antioxidant