EVALUATION OF ANTIOXIDANT PROPERTIES AND COLOR STRUCTURE FOR SOME NATURAL CONCENTRATES FROM BERRIES AND GARDEN FRUITS

Abstract

In this paper it was determined the antioxidant properties – evaluated by FRAP and DPPH methods, total polyphenols content, monomeric anthocyanins amount and color structure for natural concentrates obtained from berries (bilberry, gooseberry, raspberry, blackberry) and garden fruits (cherry and strawberry). The antioxidant capacity determined by FRAP method was presented the values between 149.5-444.38 mM Fe2+/L and in the case of DPPH assay the obtained values was situated in the range 10.97-40.60%. Polyphenols content from analysed concentrates was situated in the range 86.57-217.60 mM gallic acid/L and the amounts of monomeric anthocyanins it was found in the range 8.47•103-23.58•103 mg/L calculated as cyanidin-3-glucoside. In the case of color structure analysis, it was determinate the fraction of color due to monomeric anthocyanins, copigmented anthocyanins and polymeric pigments. For all analyzed concentrates, the monomeric anthocyanins represent the main fraction which contribute to the final color of products. For concentrates obtained from garden fruits the percent of color due to monomeric anthocyanins is 59-66%, comparativelly with the case of natural concentrates from berries (68.41-77.55%). Copigmented anthocyanins and polymeric pigments contribute in small measure to the natural concentrates color.