Sequential determination of FAMEs, total fat and free fat determination

The Nutrition Facts Label is nowadays fundamental for packaged foods and drinks. The U.S. Food and Drug Administration (FDA) has recently updated the information required on nutrition facts labels to better inform consumers on quality and nutritional parameters of products.
Together with total fat information, manufacturers must also declare the fatty acid composition on their packaging. For example, the EU regulation requires the declaration of the saturated, monounsaturated, and polyunsaturated content of foods. These requirements clearly increase the number of food samples that manufacturers and contract labs have to analyze.
Fatty acid analysis can be performed via gas chromatography, but this technique is not capable to analyze directly triglycerides of fatty acids. For this reason, a sample preparation which involves extraction and derivatization is needed prior to the GC quantification. This procedure is called Fatty Acid Methyl Esters (FAMEs) analysis which requires the formation of a moderately volatile and non-polar methyl ester of the target fatty acids, suitable for GC analysis.
Despite the various protocols available, all of them are time-consuming and limited in providing a fast and high-throughput solution to fit the growing needs of food producers and contract laboratories.
Microwave energy source has been widely applied both in elemental and molecular sample preparations to enhance and speed up reaction processes.

In this study, saturated, monounsaturated, and polyunsaturated acids were quantified via microwave assisted FAME procedure. Two innovative methods (A and B) were compared to certified reference material, FAPAS and IFIP samples, and to Reg UE 1833/2015 12/10/2015 GU UE L266 13/10/2015 method, for samples purchased at grocery stores.
Simultaneous hydrolysis and extraction followed by derivatization were performed in METHOD A enabling total fat determination at first, and subsequently, FAME analysis.
Microwave assisted extraction followed by derivatization was instead performed in METHOD B enabling free fat determination at first, and subsequently, FAME analysis.
Several food samples were tested ranging from seeds, legume soup, liver patè, rice, chips and several types of vegetal oils. The samples were selected to test different kinds of food matrices and to explore a wide range of fat values: saturated (0.18-14.40%), monounsaturated (0.37-64.70%) and polyunsaturated (0.98-58.85%). As reported in Figures 3-5, for all the ranges tested, the measured saturated (figure 3), monounsaturated (figure 4) and polyunsaturated (figure 5) fat contents were always in the acceptance range of the certified materials. Figures 3-5 show that both METHODs A and B are suitable for FAME determination ensuring accurate and precise data. Additional considerations should be pointed out on METHOD A, which involves a hydrolysis reaction, possibly a critical point for the final integrity of the FAME. As shown in Figures 3-5, microwave assisted hydrolysis, thanks to its fast reaction time, does not affect the FAME profile making this method the ideal solution for fat analysis. Despite the availability of several FAME determination protocols, the ETHOS X methods enhance fat determination by performing fast FAME preparations with the integrated possibility to determine total fat or free fat value with two available methods.