45F-19 |
Polyphenolic composition and antioxidant properties of pears |
A. DI MAURO, R. W. DURST, and R. E. WROLSTAD. Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331-6602 Pears are known to contain substantial levels of polyphenolics that may provide health benefits as dietary antioxidants. To better evaluate their nutritional properties, the polyphenolic composition of the edible portions of different cultivars is needed. Our objectives were to determine total phenolics, total anthocyanins, polyphenolic profiles (dihydrochalcones, flavan-3-ols, flavonols, anthocyanins, hydroxycinnamates), and antioxidant properties in extracts from six Pacific Northwest pear cultivars. We also wanted to compare their distribution in peel and flesh and the differences between two different maturity stages: unripe and optimum ripeness for human consumption. Anjou, Red Anjou, Bartlett, Comice, Gold Bosc, and Starkrimson pears were peeled, cored and the portions weighed. Peels and flesh were cryogenically milled and extracted with acetone and partitioned with chloroform. Total phenolics were determined by the Folin-Ciocalteau method. Monomeric anthocyanins were measured using the pH-differential method and quantification of phenolics and flavonoids, included anthocyanins, were achieved by HPLC with UV-visible diode-array detection. The antioxidant activities was determined by the Oxygen Radical Absorbing Capacity (ORAC) and Ferric Reducing Antioxidant Potential (FRAP) assays. Our results showed that total phenolics and antioxidant activities were highest in the peel. Among the six cultivars ripe Starkcrimson showed the highest content both in total phenolics (374 mg/100g GAE) and in monomeric anthocyanin (14 mg/100g). Anjou samples had the highest content of total phenolics in the flesh. Chlorogenic acid was the major polyphenolic compound in both peel and flesh for all cultivars (from 22% of total phenolics in Gold Bosc peel to 87% of total phenolics in Anjou flesh). Pears are high in polyphenolics, and a good source of dietary antioxidants. Since the peels are particularly rich in these compounds, processing wastes from canning and juice manufacture are potential sources for these phenolic antioxidants.
Session 45F, Fruit & Vegetable Products: Fruits (Fresh)
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