Structural changes of triacylglycerol and diacylglycerol fractions during olive drupe ripening

Triacylglycerols [TAG] and diacylglycerols [DAG], significant acylglycerol fractions of olive oil, were studied in order to determine the fatty acid distribution among the sn- positions of their carbon back bone at different stages of drupe ripening. The fatty acid composition of the sterically numbered positions of the TAG fractions of differently ripened samples were evaluated by a procedure based on the use of diacylglycerolkinase. The three isomeric DAG classes sn-1,2-, sn-2,3- and sn-1,3- were separated by normal phase-high performance liquid chromatography; their abundance, relative ratios and fatty acid composition were then determined by high resolution gas chromatography. The purpose of the study was to verify if this information would provide a better understanding of olive characteristics that would be pertinent to the determination of the best harvesting times to obtain the best oil yield and quality as well as to study the correlations between the parameters of these DAG classes and the product characteristics (such as preservation conditions).