Anthocyanin-Based Natural Colorants: A New Source of Antiradical Activity for Foodstuff

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Abstract
The antiradical capacity (radical scavenger capacity, RSC) of anthocyanin-based fruit extracts prepared in the laboratory (black chokeberry, black-thorn, and strawberry) was studied by using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•). To determine their RSC, the second-order rate constant (k2) for the oxidation of these extracts by DPPH• was calculated. The value of k2 was compared to that used in the food industry as natural (α-tocopherol) or synthetic (butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA)) antioxidants, as well as for a commercial elderberry concentrate and a synthetic colorant (Ponceau 4R). The k2 values ((mg/mL)-1 s-1), in methanol at 25 °C, were 1.87, 0.7, 0.42, 0.2, 0.05, 0.03, and 0.008 for α-tocopherol, black chokeberry, BHA, black-thorn, BHT, strawberry, and elderberry, respectively. Ponceau 4R lacked RSC. Therefore, these natural colorants proved to be a combined source of color and RSC for food material. Keywords: Anthocyanins; colorants; radical scavenger; DPPH; kinetics