Focused microwave-assisted Soxhlet extraction: a convincing alternative for total fat isolation from bakery products

An approach for automated fast extraction of the fat content in bakery products based on focused microwave-assisted Soxhlet extraction (FMASE) and gravimetric determination is proposed. The main factors affecting the extraction efficiency—namely, power of irradiation, number of cycles and irradiation time—were optimized using experimental design methodology. The proposed method was applied to six samples, which were classified in two groups—namely, snacks and cookies. The results obtained agree with those provided by the AOAC 920.39 reference extraction method. No significant differences in the extraction efficiency of the fat content in bakery samples using FMASE versus the official method were found. Moreover, a drastic reduction in both the extraction time (60 and 35 min versus 16 and 8 h, respectively, for the two above commented groups) and sample handling are achieved with similar precision (expressed as repeatability and within-laboratory reproducibility standard deviation) to that provided by the AOAC 920.39 method. In addition, the proposed method is cleaner than the reference method as 75–80% of the extractant is recycled.