Changes of anthocyanins, anthocyanidins, and antioxidant activity in bilberry extract during dry heating

Document Type

Article

Publication Date

8-1-2008

Abstract

Thermal stability of 10 anthocyanins found in a bilberry extract was studied at different heating temperatures and times. Degradation of the 10 anthocyanins, delphinidin, cyanidin, petunidin, peonidin, and malvidin derivatives with different conjugated sugars, followed 1st-order reaction kinetics at heating temperatures 80, 100, and 125°C. Though the degradation rate constants of anthocyanins were not significantly different from each other at the same heating temperature, they increased drastically when heating temperature was increased to 125°C. At that temperature, the half-lives for all anthocyanins were less than 8 min. The degradation rate constants followed the Arrhenius equation. The trend of lower activation energy of the anthocyanins with arabinoside than with galactoside or glucoside was observed. These conjugated sugars were cleaved from the anthocyanins to produce their corresponding anthocyanidins or aglycones during heating. The production of anthocyanidins increased constantly and was converted from approximately 30% of the degraded anthocyanins when heated at 100°C for up to 30 min. At 125°C, the increase of anthocyanidins lasted for 10 min, after which the degradation rate of anthocyanidins exceeded the production rate. Antioxidant activities of the heated extracts were estimated by measuring DPPH (2, 2′-diphenyl-1-picrylhydrazyl) free radical scavenging activity. The extracts heated at 80°C for 30 min, 100°C for 10 and 20 min, and 125°C for 10 min had higher free radical scavenging capability than unheated extract. © 2008 Institute of Food Technologists®.

Publication Source (Journal or Book title)

Journal of Food Science

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