文摘
Fresh bayberries (Myrica rubra Sieb. et Zucc.) were processed into juice at an industrialized scalewith four treatments: control, SO2 addition, pasteurization of the crushed pulp, and blanching beforefruit crushing. Changes in anthocyanin pigments and polyphenolics (hydrobenzoic acids and flavonolglycosides) were monitored during processing. Centrifuged juice yield ranged from 73 to 78% (w/w),but only 12-27% of the anthocyanins and 20-32% of the polyphenolics were recovered in theultrahigh-temperature (UHT) juices. Fifty-two to 58% of anthocyanins and 30-35% of polyphenolicswere present in the centrifuged cakes. The initial processing steps of blanching, crushing,pasteurization, and depectinization caused a great loss of total and individual polyphenolics. Totalmonomeric anthocyanins were significantly higher (p < 0.05) in pasteurization- and blanching-treatedsamples than those in the SO2 treated samples, whereas those in the SO2-treated sample weresignificantly higher (p < 0.05) than those in the control juice. Overall polyphenolic levels weresignificantly higher (p < 0.05) in pasteurization- and blanching-treated samples than in the SO2-treated and control samples after each processing step. Important changes occurred in thepolyphenolic profile with a 50-150% of hydroxybenzoic acids increase due to the free gallic acidfrom the flavonol glycoside-gallates during the initial processing steps. Flavonol deoxyhexosides weremore stable than the flavonol hexosides during bayberry juice processing.Keywords: Bayberry; Myrica rubra Sieb. et Zucc.; polyphenolics; anthocyanins; SO2; pulp pasteurization; blanching; juice processing