June 8, 2023

Hardwood Paroxysm

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Olive oil and heavy metals can interact?

Our project is important because it was able to analyze the interaction between olive oil and heavy metals. We won the “Expo Sciences” event in Luxembourg (28 September – 1 October 2023) and were honored at FAST in the Italian selection for the European competition “Youth and Science 2023”. We have studied the decomposition of olive oil upon contact with some minerals. Triglycerides made up of glycerol and oleic acid are the most abundant fats in olive oil. In each of five wide-mouthed flasks we put a known amount of oil. In each of these four we have inserted metal sheets: copper, lead, zinc, aluminum. The fifth, without foil, is the reference. We covered the mouth of the flask with paper to leave an opening for air to circulate when it came into contact with the oil. We evaluated two parameters: acidity and iodine number to differentiate the oil in different situations. Current legislation categorizes an oil as extra virgin if its acidity is between 0.0 and 0.8 and is expressed as a percentage (%) of oleic acid. When the bottle is opened, the acidity of the oil is 0.31. Acidity measured after ten days shows a slight decrease with respect to the initial period and this may be due to the free carboxylic acids of the oil attacking the remaining oxide patina on the foil. Two and a half months after the start of the experiments, once this phenomenon is over, the acidity increases in all samples including the one that was in contact with air only. This seems to indicate that the metal does not have a catalytic effect in the lipid hydrolysis reaction leading to release of carboxylic fatty acids and increased acidity. In any case, the oil, based on this parameter, retains its ultra-virgin nature. The degree of unsaturation is represented by the iodine number, which is rather modest when compared to the value of soybean oil.

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