A taste of bio – chemistry
Vegetable oils are tryglicerides extracted from a plant.
Tryglicerides are bio – chemical compounds that occurs in nature. They are formed by combining glycerol with three molecules of fatty acids. Depending on the oil source you obtain different tryglicerides.
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Here is an example of unsaturated fat triglyceride compound. On the left there are glycerol molecules, on the right there are three different molecules of fatty acids: in this case we have, starting from the top, palmitic acid, oleic acid and alpha-linoleic acid.
When the fatty acids are not attached to other molecules they are known as “free” fatty acids. The measure of these broken bounds in triglyceride compounds is FFA parameter. The measurement is possible through the Free Fatty Acids Test.
The acid content in biofuels
The acid content of fats and oils is given by the quantity of free fatty acids deriving from the hydrolytic rancidity of triglycerides. In short, FFA measure the level of degradation of the fats.
Recently the FFA parameter is used more and more to detect the conditions of vegetable oils used as biofuels, that produce green power. Why? Because acidity is dangerous for engines and boilers in which the oils are inserted and can cause damages.
How to determine Free Fatty Acids parameter?
The reference method to determine FFA is titration. It requests an equipped lab, specific facilities and professionals. Acidometer is another method, simpler but low sensitive and low accurate.
More than one instrument of the CDR FOODLAB® line offer an alternative: a reference method compliant FFA test that do not request labs, skilled staff or specific glassware. The method is always the same: very easy to realize, in fact the testing time is 1 minute per test, high sensitive and accurate, proved by a correlation with AOCS Official Method (Ca 5a-40).
It works thanks to a colorimetric reading at 630 nm that offer the proportional concentration of acid in the sample. Free fatty acids of the sample, at pH minor than 7.0, react with a chromogenous compound and decrease its color. The decreasing of color expresses the percentage of acid. The kind of acid depends on the kind of matrix. The most common used biofuels are palm oil, rapeseed oil, sunflower oil, soybean oil, fried oil or waste oil.
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