This study was carried out in order to check for the influence of drying parameters on the phenolic compounds and antioxidant activity on two apricot cultivars (Pelese and Cafona) using two sets of air drying temperatures: (1) air temperature at 55°C; (2) air temperature at 75°C. Whole fresh and dried fruits were assessed for: phenolics, ascorbic acid, antioxidant activity and redox potential (all parameters were calculated on a dry matter basis). Analysis of data shows that the decrease in chlorogenic and neochlorogenic acid in Cafona cultivar is higher at the lower drying temperature. Catechin showed the same behaviour of hydroxycinnamic acids in both cultivars, while the decrease in the other compounds was significantly more marked in the sample dried at 75°C. The antioxidant activity increased significantly in Cafona fruits and this increase was confirmed by a diminution of the redox potential.

No abstract

Prunes, obtained by drying certain cultivars of plums, have greater antioxidant activity than most other fruits and vegetables. Recent research has attributed only a minor part of this antioxidant activity to phenolic compounds, and it has been hypothesized that most of the antioxidant activity is caused by unknown or new products created during processing. In this study, the relationship between the antioxidant properties of prunes and their phenolic compound and brown products content has been investigated. The latter is a result of the nonenzymatic browning reaction. The results show that most of the antioxidant activity of fresh plums is caused by the polyphenolic fraction. The prunes, obtained by drying at 60 and 85C, despite the significant decrease in polyphenols, showed an increase in antioxidant activity. This was mostly because of the nonenzymatic browning reaction products, mostly low molecular weight compounds, whereas polyphenols contributed only to 23% of the total value. PRACTICAL APPLICATIONS Results of this research could have direct or indirect applications. First of all, results give evidence of the best drying conditions related to the nutritional profile of the prunes. Results related to the antioxidant activity of melanoidin compounds can, moreover, stimulate medical researcher to test if melanoidin extracts are really in vivo or ex vivo antioxidants, and in that case, producers of functional foods or food ingredients can be encouraged to try to isolate and characterize the compounds responsible for increased antioxidant activity.

No abstract