Document Type : Complete scientific research article
Authors
1
MSc graduate, Department of Food Hygiene, Faculty of Veterinary Medicine، Shahid Chamran University of Ahvaz، Ahvaz، Iran
2
Associate Professor, Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz، Ahvaz،Iran
3
Professor, Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz، Ahvaz، Iran.
4
Ph.D. in Analytical Chemistry, Chemistry Department, College of Science, Shahid Chamran University of Ahvaz، Ahvaz، Iran.
Abstract
Abstract
Background and Objective: Sesame seeds (Sesamum indicum L.) and tahini are rich sources of various mineral elements, and their consumption is recommended in the diet. However, these products may also become contaminated with heavy metals through specific agricultural or industrial processes. Considering the high nutritional value and widespread consumption of sesame seed and tahini, either raw or as ingredients in various food products, this study aimed to investigate the effects of different processing stages of sesame seed and its conversion into tahini on the contents of essential minerals and heavy metals.
Materials and Methods: Samples were collected from various stages of sesame seed processing into tahini, including raw sesame seed, washed raw sesame seed, hulled sesame seed, roasted sesame seed, and Tahini. After sample preparation and ashing, the concentrations of heavy metals—arsenic (As), mercury (Hg), cadmium (Cd), aluminum (Al), and lead (Pb)—and essential minerals—sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), molybdenum (Mo), cobalt (Co), chromium (Cr), and nickel (Ni)—were determined using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP–OES). The statistical analysis was performed using one-way analysis of variance (ANOVA), and mean comparisons were conducted using Tukey’s test at a 95% confidence level with Minitab software.
Results: Both sesame seed and tahini contained considerable levels of essential macro-minerals (Na, K, Ca, Mg) and trace elements (Fe, Zn, Cu, Mn, Mo, Co, Cr, Ni). The various processing stages had different effects on the mineral composition. Overall, the contents of K, Mn, Cr, Mo, Ni, and As significantly decreased after washing (P < 0.05). Similarly, levels of K, Mg, Ca, Mn, Cr, Co, Ni, and Mo significantly decreased following dehulling compared with raw sesame seed (P < 0.05). Roasting of dehulled seeds caused a non-significant increase in Na, Cu, Cr, Mo, Ni, and Co contents (P > 0.05). In the final tahini product, Na, Zn, Fe, and Cu levels were significantly higher than in raw sesame seed (P < 0.05), while Ca, Mg, Mn, Cr, Co, and Mo contents were significantly lower (P < 0.05). Among the heavy metals, only As and Pb were detected in raw sesame seed; Cd, Hg, and Al were not detected in any samples. Washing significantly reduced As and Pb levels (P < 0.05). Dehulling had no significant effect on As content, whereas Pb content slightly increased without statistical significance (P > 0.05). Grinding and tahini production caused a significant increase in Pb concentration (P < 0.05), whereas As levels in both tahini and roasted sesame seed were significantly lower than in the raw seeds (P < 0.05).
Conclusion: The findings indicate that sesame seed and tahini are rich sources of essential minerals and can contribute to dietary mineral intake. Washing sesame seeds before consumption is recommended to reduce heavy metal contamination, particularly Pb and As. Nevertheless, due to potential contamination risks, moderate consumption of dehulled sesame seeds and tahini should be considered in daily diets. It is further recommended that tahini producers use sesame seeds with minimal heavy metal contamination and employ proper processing equipment to ensure the safety of this popular food product.
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