Studying the oxidation and the antiradical activity of betalain from beetroot

Abstract

Betalains, the pigments responsible for the colour of beetroots, and peroxidases coexist in the same tissue but are compartmentalised. Beetroot storage and/or processing breaks down the compartments, resulting in betalain oxidation and colour loss. This can be observed using two simple techniques (centrifugation and spectrophotometry). The in vitro oxidation of betalains by the H₂0₂/peroxidase system clearly demonstrates the fate of these pigments when beetroots are degraded in vivo during postharvest storage and /or industrial processing. The health giving properties of fresh vegetables directly depends on phenolic compounds and the antioxidant capacity that they have, since these compounds act as free radical scavengers preventing activated oxygen species from oxidising biological tissues. Therefore the measurement of antioxidant capacity reveals much about the nutritional value of vegetables: the greater their antiradical activity, the greater their capacity for scavenging free radicals. This paper is intended for biochemistry and food technology students with a knowledge of spectrometry and centrifugation techniques, who wish to deepen their knowledge of the important alterations that occur in the organoleptic characteristics of fresh fruit and vegetables.