Contribution of Melanoidins to the Antioxidant Activity of Prunes

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.