Determination of oxalic acid in vegetables

Abstract

Oxalate is a common constituent of plants, and several species, including some crop plants, accumulate high levels of this C2 dicarboxylic acid anion. Depending upon species, oxalate accumulates primarily as soluble oxalate, insoluble calcium oxalate, or a combination of these two forms. From an agricultural point of view, oxalate is of concern because of health-related hazards due to high oxalate levels in food and animal feed (Libert and Franceschi 1987). Reviews on oxalate in plants by Oke (1969) (nutritive aspects), Hodgkinson (1977), and Franceschi and Horner (1980) (calcium oxalate in plants) have appeared. Several other works have been reported on antinutritive effects and toxicity of dietary oxalate (Grott 1942; Wittwer et al. 1947; Oke 1969; James 1970; Sing et al. 1972; Chadwick et al. 1973; Hodgkinson 1978; Swartzman et al. 1978; van Campen and Welch 1980; Gillooly et al. 1983; Kelsay 1981, 1985).