Effect of extraction method on chemical, volatile composition and antioxidant properties of pomegranate juice

摘要

The study investigated chemical, volatile composition and bioactive compounds extracted from different fruit fractions of pomegranate (Punica granatum L.) cv. Wonderful. Juice variants evaluated included juice extracted without crushing the seeds using a juice extractor (arils), juice extracted by crushing the seeds using a blender (arils plus seed), juice extracted by pressing a whole fruit using a squeezer (whole fruit) and juice extracted from halved fruit using a commercial hand press juicer (halved fruit). There were no significant differences (P > 0.05) in total soluble solids (degrees Brix) content in pomegranate juice obtained from different fruit fractions. Juice extracted from halved fruit had higher titratable acidity (1.78 mg citric acid/100 mL), lower pH content (1.58) and juice yield (28.01%). The lowest citric acid content was observed in blended juice (18.96 g/L) and high juice colour (2.69). Fructose content did not vary in all extraction methods. Catechin and epicatechin were the most dominant flavonoids whereas gallic acid was the dominant phenolic acid identified in all extraction methods. The total phenolics, tannins, flavonoids and anthocyanin content in the investigated juice ranged from 138.36 to 289.94 mg gallic acid equivalent/100 mL, 120.00 to 267.10 mg gallic acid equivalent/100 mL, 23.35 to 50.39 mg catechin equivalent/100 mL, and 10.96 to 13.91 mg cyanidin 3-glucoside equivalent/100 mL crude juice, respectively. Furthermore, halved fruit juice had high radical scavenging activity and ferric reducing antioxidant power. The most abundant volatile compounds were ethyl acetate (21.35-31.45%) and 3-octanone (8.12-18.74%) in all the juice variants. Principal component analysis (PCA) also revealed that the chemical, volatile and bioactive compounds separated the investigated juice extraction method. The results of the study provide information on the importance of methods of extraction on the quality of pomegranate juice. (C) 2015 SAAB. Published by Elsevier B.V. All rights reserved.