Effect of drying temperature on the bioactive compounds content of rose hips (Rosa canina L.)

Abstract

Dog rose (Rosa canina L.) is a beautiful ornamental plant that provides fruit with high biological value. To be available throughout the year, rose hips need to be conserved, such as dried and canned. For this reason, a study was undertaken to investigate the effects of drying as the most common method for preservation. Therefore, the influence of variation drying temperature (20, 35 and 68 °C) on the content of flavonoids, total polyphenols, ascorbic acid, carotenoids and antioxidant activity - determined using the free radical source DPPH (2,2-diphenyl-1-picrylhydrazyl) and a test measuring the measuring of compounds to reduce ferric ions Fe3+ (FRAP) - of rose hips was the main topic in this study. Drying decreased total polyphenols (from 38.06 mg g–1 by fresh fruits to 9.41 mg g–1 drying to 20 °C), ascorbic acid (from 2000.5 mg 100 g–1 by fresh fruits to 1308.2 mg 100 g–1 drying to 68 °C) and flavonoids, the latter only in those dried at 35 °C (0.54 mg g–1), but did not affect the antioxidant activity of DPPH (84.21–85.73%) and FRAP (2.99–3.41 mgTr g–1). The study also showed that the extraction time influenced the antioxidant activity level of fruit infusions for the first time. The antioxidant potential FRAP value increased systematically with extraction time, but the DPPH values of extracts obtained from dried rose hips were not affected by the extraction time. These results indicate that changes in the antioxidant activity of extracts may not be linear and that the choice of the time of evaluation of this activity may determine the results.