Determination Of Heavy Metals In Edible Palm Oil Adulterated With Plant Dye

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Different oil samples collected from Edo state, Enugu State and Abia State were produced using different methods. Oil from Abia State was produced by mechanical processing and adulterated with local additive red plant dye. While one from Benin was produced by extraction using N-Hexane, the fresh oil from Benin was produce by mechanical processing and the oil from Nsukka Enugu State was produced locally by mastication prior to cooking. The samples were analyzed for their relative density, saponification value, iodine value, acid value peroxide value and free fatty acid value. The values of the analyzed parameters were compared with each other. The result of the analysis shows that adulteration and method of production do not affect density of oils. The adulterant significantly increases the saponifiaction and iodine value of red palm oil and increases the color quality of red oil. This analysis was proceeded with determination of Arsenic, lead, Nickel, chromium and mercury in the oil samples which was done using Atomic absorption spectrometer (AAS) the edible oil was dissolved with N-Hexane followed by determination of As, Pb, Cr, Ni, and Hg with atomic absorption spectrometer and the result reveals that the concentration of Nickel was 2.62ppm, 2.78ppm, 0.36ppm and 0.78ppm for fresh Benin oil, fresh Nsukka oil, chemically extracted oil and Abia state adulterate oil respectively. Also chemically extracted oil from Benin and adulterated Abia oil has chromium 0.48ppm and 0.18ppm respectively while other parameters were below the detection limit of the atomic absorption spectrometer.




Palm oil is extracted from the pulp of the fruit of the palm Elaeis gulneensis. Palm oil, coconut oil and palm kernel oil are edible plant oil derived from fruits and seeds of palm trees respectively. (Okonkwo, 2010).

Palm oil should not be confused with palm kernel oil and coconut oil because palm oil is naturally reddish in color, due to its high content of beta-carotenes. It is semi solid at room temperature. Palm oil, palm kernel oil and coconut oil are three of the few highly saturated vegetable fat.

Palm oil is a common cooking ingredient in the tropical belt of Africa Nigeria, Malaysia, South East Asia and Parts of Brazil. Its increasing use in the commercial food industry in other part of the world is buoyed by its lower cost and high oxidative stability (saturation) of the refined product when used for frying (Cottrell, 1991).

Red palm oil is a highly nutritious food ingredient and its name is driven from its characteristic dark red color, which comes from carotenes and lycopene the same nutrients that gives tomatoes, carots, and other fruits and vegetables, their rich colors (Mensink, 1992).

Red palm oil contains at least 10 (ten) other carotenes along with tocopherols and tocotrienols (members of vitamine E) phytosterols and glicolipids (Benade, 2003).

According to Folklore, Nursing mother “By adding red palm oil into their food (diets) can double or triple the amount of vitamin A in breast milk in addition to all the carotene bodies”. (Tay et al, 2000).

Among all these nutritional important of palm oil it is found that there are traces of toxic heavy metals in red palm oil. (Syr-song-chen, 2003).

These heavy metals includes Arsenic, chromium among other metals. The study of arsenic in red oil in Taiwan, China reveals that the acceptable value of organic arsenic in edible red palm oil is 0.1ppm (Anon, 1993). No study has shown on other metals like copper, lead, mercury, Aluminum to name but a few on red edible oil.

Arsenic is a hazardous heavy metal; the malignant symptoms may appear even when trace arsenic is ingested. The toxicity of arsenic has been shown that it binds to enzymes which are inhibited functioning (Wang, 1989), the toxicity of arsenic depends on the forms of chemical compound. The trivalent arsenic shows high toxicity. It can be relatively retained in the tissue, but slows excretion. The organic arsenic complex which is commonly found in food are readily absorbed in the body and excreted through urination (Anon, 1993).



There has been an indiscriminate reported on the adulteration of red palm oil.

There has been an increase in the cancer cell growth among the people in Nigeria. (Syr-song-chen,2003)

There is a suspect that there are some traces of heavy metal in red oil or adulterated palm oil that constitute to the development of malignant growth in the body during the long tern consumption of food processed with such an oil.

In an attempt to maintain market value and obliterate poor quality, peddlers of palm oil are known to


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