Bioaccessibility of Heavy Metals in Raw and Processed Alternanthera sessilis and Centella asiatica: An In Vitro Study

Abstract

Heavy metals cause considerable hazards to food safety due to their long-term presence in the environment and their ability to accumulate within the food chain. Upon consumption, even small amounts of these metallic substances can have harmful effects on human health. The current investigation aimed to assess the in vitro bioaccessibility of Ni, Cd, Cr, Pb, and Cu in two commonly consumed green leafy vegetables in Sri Lanka, namely Alternanthera sessilis and Centella asiatica. Composite samples of A. sessilis and C. asiatica were randomly collected from the Western Province, Sri Lanka. The edible parts of each leafy vegetable sample were divided into three test portions of 200 g and subjected to the following treatments: Treatment 1 - raw sample, Treatment 2 - cooked sample, and Treatment 3 - stir-fried sample. The in vitro bioaccessibility of heavy metals in raw, cooked, and stir-fried samples was determined using a physiology-based extraction test (PBET). In contrast to overall concentrations of heavy metals in A. sessilis and C. asiatica, the bioaccessible fractions of metals were significantly lower for raw, stir-fried, and cooked samples (P<0.05). Moreover, significant differences were detected in metal concentrations between intestinal and gastric stages. The average bioaccessibility (%) of Cu was considerably greater in the intestinal stage, while Cr, Cd, Pb, and Ni were more elevated (P<0.05) in the gastric stage. Additionally, cooking and stir-frying reduced the bioaccessibility of metals compared to the raw samples.