Synergistic Green Valorization of Lemon and Apple Pomace for Ecofriendly Detoxification of Heavy Metals in Oryza sativa Rice Grain

Heavy metal contamination in rice, a staple food in northern Iran, poses significant health risks to consumers. This study aimed to evaluate the effectiveness of natural biosorbent, combination of apple pomace and lemon peel powders, in reducing heavy metal concentrations in rice grain ( Oryza sativa ) consumed in northern Iran. Rice grain samples were collected from Guilan and Mazandaran provinces, and heavy metal analyses were conducted by inductively coupled plasma mass spectrometry (ICP‐MS). Various pretreatment strategies were applied, including rinsing, soaking in 2% saline solution for 1 and 2 h, and incorporating biosorbents at different concentrations (0%, 1%, 2%, 3%, 5%, 10%, and 15%). Samples were then cooked using two methods: Kateh (traditional Iranian method) and draining (general method) to investigate the effect of biosorbent effect on heavy metal decontamination. The results showed the presence of lead (Pb), nickel (Ni), and cadmium (Cd) in rice grain sample, at levels of 2.918, 31.722, and 0.204 mg/kg, respectively. Both rinsing and salt soaking significantly reduced heavy metal levels in raw rice grain ( p < 0.05). Increasing the biosorbent concentration led to greater reductions, with the most substantial decrease observed at 15% biosorbent. Postcooking analysis indicated that both cooking methods further reduced metal concentrations; however, the Kateh method demonstrated superior efficacy, likely due to extended contact time and retention of the cooking medium. Notably, using 5% biosorbent in the Kateh cooking method yielded the most effective in reduction of Pb, Ni and Cd to 0.016, 0.159, and 0.031 mg/kg without any difference in the sensory acceptance. These findings suggest a promising, low‐cost, and practical approach for mitigating heavy metal contamination in rice grain through household‐level interventions.