Polyphenolic content and color of seedless and seeded shade dried Chinese raisins

Abstract

29 grape cultivars, of seeded and seedless raisins from black, reddish-brown and yellowish-green grape varieties were examined to determine the relationship between grape color, seeded status and raisin phenolic content. The raisins were analyzed for phenolic profile, total phenolic (TP) and flavonoid contents (TF), and antioxidant activities (DPPH, ABTS and FRAP). We found that despite the perception that dark colored raisins, contain higher levels of polyphenolic antioxidants, only seedless raisins from black grapes were higher in TP. Black raisins exhibited significant higher values of TP and FRAP activity than reddish-brown and yellowish-green raisins. The values of TP, TF, DPPH, ABTS, and FRAP capacities for seeded raisins were higher than those of seedless samples. Raisins could be classified into three groups and some raisins differing in seed-bearing status or color were grouped together, indicating the antioxidant properties of raisins were not only determined by raisin color, but also by their seed-bearing status.