Today, more than at any time past, the role of edible oils and fats in the manufacture and preparation of various foods has become a major one. Consequently, the need for thorough testing of these substances has now become of equal importance. These materials vary widely in nature and include the relatively cheap cooking aids that are commonly used to fry snack foods, as well as high-end products such as extra virgin olive oil. In all cases, the quality of these products can have a profound effect on the taste and the quality of the foods that are cooked with them or to which they may have been added.

These substances are inherently labile and when exposed to moisture, oxygen or heat, they have a tendency to degrade. Often, the process of chemical degradation is accompanied by a parallel deterioration in their taste and so tests that are designed to detect the products of decomposition are an essential requirement within the industry.

One of the confirmatory signs that suggest edible oils and fats may have become denatured is a raised level of free fatty acids (FFA). Testing for the increased FFA levels that result from the hydrolysis of triglycerides is a simple matter that involves titration with a suitable alkali. In this procedure, the alkali is added slowly until a pH meter indicates that the mixture is neutral. Then, from the volume of alkali added, the percentage of free fatty acid present can be calculated and in this way, a technician can determine whether the sample falls within or beyond acceptable limits. The development of automated titration equipment has eliminated the need for manual analysis, both speeding up the screening process and improving its accuracy.

Water is a fairly common contaminant of these products and although it is clearly not toxic in nature, its presence in relatively low concentrations can cause them to become rancid and therefore unpalatable. In this instance too, the spoilage is the consequence of an unplanned chemical change. On this occasion, the degradation arises from the oxidation, by water molecules present, of the triglycerides which then form peroxides. The concentration of peroxides present is a measure of the degree of oxidation and, in the testing of edible oils and fats, this may be determined using a method known as the Karl Fischer titration.

Another task for the laboratory is to determine the proportion of unsaturated fats present in these products. Unsaturated fats are characterised by the presence of double bonds and these have the ability to bind with iodine. Determined by means of a complex titration, the higher the so-called iodine number, the higher the proportions of unsaturated molecules present in the sample.

All of these processes may be performed manually when they rely on the ability of a technician to judge the colour changes that signify the completion of the analysis. The result is a process that is time-consuming and whose results are prone to the subjectivity of the investigator. The introduction of technology that is able to automate each of these titrimetric procedures has resulted both in vastly improved turnaround times and greater accuracy. A specialist in this field, all the requirements for automated testing of edible oils and fats are available from us at IEPSA.

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