Fast method for the determination of total fat and trans fatty-acids content in bakery products based on microwave-assisted Soxhlet extraction and medium infrared spectroscopy detection

A procedure based on focused microwave-assisted Soxhlet extraction (FMASE) has been tested to develop a rapid isolation of fat from bakery products, followed by a modification of the American Oil Chemists’ Society (AOCS) Recommended Practice Cd 14d-96 for determination of trans fatty-acids content. This last step is based on rapid attenuated total reflection (ATR) infrared (IR) spectroscopy. The proposed method was applied to 14 bakery samples. Validation was carried out by comparison with the Folch reference extraction method and the same determination step. Similar extraction efficiencies were obtained in addition to advantages of the FMASE method such as a drastic reduction of both the procedure time and sample handling—1 h versus 4 h—and less organic solvent was needed (75%–85% of it was recycled). This good agreement between the results provided, both by the FMASE method and reference method, demonstrates the usefulness of the former as routine method, as a way in the initiative of adding trans fat content to the label of processed foods, either by legislation or as quality index to be implemented in the near future.