Abstract:

Three process conditions (namely, ethanol concentration, solid/liquid ratio and length of extraction time) for the ultrasonic-aided extraction of polyphenols from seabuckthorn leaves were optimized using orthogonal array design on the basis of single factor investigations. Along with this, the extracted polyphenols were added to freshly prepared apple juice in order to evaluate their fresh-keeping effect on fruit juice. The optimal ultrasonic-aided extraction conditions were found to be: ethanol concentration 60%, length of extraction time 25 min and solid/liquid ratio 1:16. The polyphenol yield obtained under such conditions was 7.385 mg/g. The extracted polyphenols added at a level of 0.10% had a significant fresh-keeping effect on apple juice.

Key words: polyphenol, ultrasonic, extraction, preservation fresh-keeping