Ultrasonication Treatment Effect on Anthocyanins, Color, Microorganisms and Enzyme Inactivation of Mulberry (M oraceae nigra ) Juice

Abstract

This study determined the effect of ultrasonication on anthocyanins, microorganisms, color parameters, polyphenol oxidase and peroxidase activities of mulberry juice. There was more than 4 log10 reduction of total plate count, yeast and mould populations. Ultrasound was found to have significantly (P < 0.05) reduced the amount of anthocyanins, with sample treated at 24 kHz for 30 min, retaining the highest percentage (94.40 ± 0.56%). Relatively, ultrasonication reduced polyphenol oxidase activity to a greater extent as compared with peroxidase activity. Maximum inactivation of polyphenol oxidase activity (45.04%) was achieved at 22 kHz for 10 min. Color brightness was significantly (P < 0.05) increased, as well as the hue and chroma for most of the samples in comparison with the control. The sample treated at 24 kHz for 20 min had the highest values for brightness, hue, chroma and total color difference, respectively as 6.8 ± 0.01, 150.96 ± 1.70, 9.02 ± 0.08 and 9.12 ± 0.13, making it the most conspicuous. Practical Applications The study demonstrated the use of ultrasound to produce a fresh-like mulberry juice that can serve as a functional food product as essential phytochemicals were preserved, particularly anthocyanins, which have been demonstrated to have therapeutic properties.