MOSH &MOAH remediation strategies and analytical challenges

Due to the lipophilic and ubiquitous nature of mineral oil hydrocarbons, vegetable fats, and oils are particularly prone to their contamination. Therefore, remediation strategies are fundamental to ensure the safety of this food commodity. Refining, composed of different key steps, among which deodorization and bleaching play an important role in contaminants removal, has been investigated in this regard.

Deodorization has previously shown the ability to remove MOAH < C25 in vegetable fats and oils, but little discussion was present regarding the removed structures. In this study, the use of GC×GC-TOFMS/FID supported the elucidation of the removal process, simplifying the sample preparation and assuring more accurate results compared to a GC-FID system.

In particular, the impact of deodorization was systematically studied using an inscribed central composite design with time and temperature as variables (0.5-4h, 150-240°C), while pressure (3 mbar) and steam flow (1 g water/100 g oil per hour) were kept constant. Response surfaces plotting the MOAH loss according to time and temperature were built for different MOAH fractions. The latter were defined based on the number of aromatic rings ( >3 or ≤3) and the C-fraction (C16-C20, C20-C24, C24-C35, C35-C40).

It resulted that from 200°C, compounds < C24, including weakly alkylated triaromatics, could be reduced below the limit of quantification, while at 230°C, it was possible to reduce >60% the C24-C35 fraction, including up to weakly alkylated pentaromatics.

Bleaching also seems to play an important role, and some preliminary results are discussed herein.