Oxalate content of purslane leaves and the effect of combining them with yoghurt or coconut products

Abstract

The total oxalate of purslane ( Portulaca oleracea L.) leaves grown in a green house was 1072.7 ± 23.2 mg/100 g dry matter (DM) while the level was 1234.1 ± 37.5 for leaves grown in shaded light in the same greenhouse. Lightly cooking the leaves grown in full and shaded light had no effect on soluble or insoluble content of the leaf tissue. Overall, leaves grown in shaded light contained higher levels of insoluble oxalates leading to an increased amount of total calcium within the leaves being bound to oxalate compared to the levels in the leaves grown in full light in the greenhouse. Addition of yoghurt, coconut milk or coconut cream to the raw leaves had the effect of reducing the overall oxalate content of the mixture by simple dilution. However, the addition of yoghurt to raw purslane leaves significantly reduced the soluble oxalate content of the mixture. The soluble oxalate content of the raw leaves was 53.0% which reduced to 10.7% when yoghurt was added to the leaves. Addition of coconut milk or coconut cream to fresh purslane leaves, while they both gave the mixture an acceptable taste, had no effect on reducing the percentage soluble oxalate content of the mixture.