Cyclic voltammetric analysis of antioxidant activity in citrus fruits from Southeast Asia

The aims of this work were principally two-fold: first, to show that cyclic voltammetry is a simple, cheap and practical method for determining antioxidants in citrus fruit juices; second, to evaluate vitamin C in four species of citrus fruits. Two are known world wide, the lemon, Citrus limon (L.) Burm.f., and the lime, Citrus aurantiifolia (Christm.) Swingle, and two are principally but not exclusively found in Southeast Asia where they are of economic importance, the sweet lime, known in Malay as limau manis and the musk lime, limau kasturi. Juices from all the citrus fruits contained antioxidants with the principal one being equivalent to vitamin C at concentrations of 1.3 mM in limau manis, 1.4 mM in limau kasturi, 1.5 mM in limau kapas and 1.8 mM in lemon. It was also evident that the citrus fruit juices contained one or two additional antioxidants, although their presence was variable. The use of differentiated recording gave greater resolution of the additional antioxidants.