Comparison of classical and alternative extraction methods for the quantitative extraction of fat from plain chocolate and the subsequent application to the detection of added foreign fats to plain chocolate formulations

Abstract

Three methods were compared for the quantitative extraction of fat from plain chocolate and cocoa products ranging from simple intermediary products such as cocoa butter, cocoa masses or liquors to market purchased chocolate samples. The classical method of extraction using an acid digestion followed by Soxhlet extraction was compared to two potentially alternative methods: microwave extraction and supercritical fluid extraction (SFE). The extracted intact triacylglycerols were then analysed directly by high temperature capillary gas chromatography (HT-GC). The results of extractions were compared by plotting the percentage areas of the three major triacylglycerols present one vs. the other. The results showed that the microwave extraction technique gave similar results to the more time-consuming classical extraction method. SFE gave results with higher standard deviations and a tendency to lower yields taking the acid digestion–Soxhlet method as the reference method. The minimal variations due to the methods did not impact the detection of foreign fats added to chocolate. However, the quantification of the foreign fats was impaired when using the SFE method compared to the other techniques due to the larger variations of replicate analyses of intact triacylglycerol profiles.