Effect of drying temperatures on the phenolic composition and antioxidant activity of pears of Rocha variety (Pyrus communis L.)

The interest about phenolic compounds and antioxidant activity has been increasing in recent years, mainly due to their beneficial effects on human health, focusing on many different food products. In this way, and since pears are an important source of dietary intake of phenolic compounds with antioxidant activity, this work was done to evaluate the phenolic content and antioxidant activity of pears of cv. Rocha from five different locations and submitted to drying at different temperatures (40 and 60 degrees C). Although the amounts of phenolic compounds are not very much influenced by drying, the antioxidant capacity does suffer a very marked decrease with drying at both temperatures, when compared to that of the fresh pears. The HPLC analysis of the phenolic extracts allowed identifying some phenolic compounds present in the pears, such as arbutin, gallic acid, chlorogenic acid, syringic acid, protocatechuic acid, catechin and epicatechin. From the results obtained in this study it was concluded that the greatest variations occurred in the peel of the pears, as compared to the corresponding pulps. Furthermore, it was possible to observe that while total phenols and ortho-diphenols do not seem to be very affected by drying, the antioxidant capacity suffers a great decrease with drying, being this effect more pronounced when the drying temperature is increased.