Free fatty acids and hexanal monitoring in cheese by HS-SPME-GC-MS: evaluation of food packaging efficiency

Introduction: This study sought to develop a quantitative HS-SPME-GC-MS method to monitor simultaneously the evolution of short and medium chain free fatty acids and hexanal during cheese storage. Indeed, food storage is associated with the production of these markers whose amounts determine the taste and the spoilage level of cheese [1,2]. Methods: Hexanal, butanoic, isovaleric, hexanoic, octanoic and decanoic acids were analyzed by optimizing the GC-MS conditions in SIM mode. Moreover, different salting-out agents (NaCl, Na2SO4, NaH2PO4 and Na2CO3) and SPME-fibers (100 µm PDMS, 75 µm CAR/PDMS, 50/30 µm DVB/CAR/PDMS and 85 µm PA) were compared to improve their extractions. Results: The 75 µm CAR/PDMS fiber and the use of NaH2PO4 as salting-out agent resulted to be the best conditions for analytes extraction. Once validated, the GC-MS method was applied on Grana Padano (GP)and fresh asiago (FA) cheeses to compare the efficacy of two packaging systems: a polycoupled packaging named Ideabrill® and a HDPE film. A progressive increase of hexanal and FFAs during storage confirmed thier adequacy as cheese deterioration markers. All along storage, the concentrations of these markers became higher in the HDPE film. After 12 weeks of study for GP and 4 weeks for FA, the Ideabrill® packaging allowed a lower increment of FFAs (11.6-fold increase for GP and 5.9 for FA) in comparison with the HDPE film (21.5-fold increase for GP and 7.4 for FA) The amounts of hexanal were also lower in the Ideabrill® packaging (0.58 against 1.04 mg/kg in GP and 0.38 against 0.55 mg/kg in FA). Conclusions: By slowing down the increment of FFAs and hexanal, the Ideabrill® packaging has proved to be more effective than a common HDPE film in the preservation of the cheeses studied. This method can represent an important solution in the food industry sector, which requires the optimization of fast and performing analytical methods for shelf life studies, quality control or active packaging development. References 1. McSweeney, P. L. H., & Sousa, M. J. Lait; 80 (3), 293-324 (2000). 2. Mannion, D. T., Furey, A., & Kilcawley, K. N. International Journal of Dairy Technology. 69 (1), 1-12 (2016).