Quantification of TMA in fishery products by direct sample analysis with high resolution mass spectrometry

Development of a screening method to rapidly discriminate extravirgin olive oil from other edible vegetable oil by means of direct sample analysis with high resolution mass spectrometry

Extra virgin olive oil is the highest quality olive oil mainly due to its beneficial constituents and nutritional properties. However, olive oil adulteration is a common fraudulent practice by deliberate mislabelling of less expensive oil categories and admixing expensive olive oils with low oils. To protect consumers from such commercial frauds, an easy and fast method to detect the real composition of oil is needed. For this study we used direct sampling analysis (DSA) coupled with a high-resolution mass spectrometer (AxION2 TOF Perkin Elmer) to analyse the fatty acid composition of three types of edible oil: extra virgin olive oil, refined olive oil and seed oil (EVOO, ROO, and SO respectively) to find a marker that could distinguish between them. Good precision in repeatability and reproducibility (RSD% < 15%) was obtained. The fatty acid ratio between the oleic acid/oleic acid dimer was able to distinguish EVOO from the other two types of oil, while the ratio between linoleic and oleic acid was found to discriminate refined oil from seed oil. The development of an easy, fast and cost-effective method can help to limit commercial frauds, increase the number of controlled samples, and enhance food control along the commercial chain.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05063-y.

A Systematic AQbD Approach for Optimization of the Most Influential Experimental Parameters on Analysis of Fish Spoilage-Related Volatile Amines

The volatile amines trimethylamine (TMA) and dimethylamine (DMA) could be used as important spoilage indices for seafood products, assisting in the determination of the rejection period. In the present study, a systematic analytical duality-by-design (AQbD) approach was used as a powerful strategy to optimize the most important experimental parameters of headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) conditions for the quantification of TMA and DMA in Sparus aurata. This optimization enabled the selection of the best points in the method operable design region for HS-SPME extraction (30 min; 35 °C; NaOH 15 M and NaCl 35%, w/v) and GC-MS analysis (80 °C; gradient 50 °C/min; flow rate 1 mL/min and splitless mode). The rejection day, estimated through the TMA concentration (>12 mg/100 g, at days 9–10), was compared with sensory (quality index method: day 7–8), physical (Torrymeter: day 8–9), and microbial (day 9–10) analysis, corroborating the suitability of the proposed approach for estimating the period for which they will retain an acceptable level of eating quality from a safety and sensory perspective.

Quantitative Analysis of Cold Stress Inducing Lipidomic Changes in Shewanella putrefaciens Using UHPLC-ESI-MS/MS

Shewanella putrefaciens is a well-known specific spoilage organism (SSO) and cold-tolerant microorganism in refrigerated fresh marine fish. Cold-adapted mechanism includes increased fluidity of lipid membranes by the ability to finely adjust lipids composition. In the present study, the lipid profile of S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C was explored using ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) to discuss the effect of lipid composition on cold-adapted tolerance. Lipidomic analysis detected a total of 27 lipid classes and 606 lipid molecular species in S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C. S. putrefaciens cultivated at 30 °C (SP-30) had significantly higher content of glycerolipids, sphingolipids, saccharolipids, and fatty acids compared with that at 0 °C (SP-0); however, the lower content of phospholipids (13.97%) was also found in SP-30. PE (30:0), PE (15:0/15:0), PE (31:0), PA (33:1), PE (32:1), PE (33:1), PE (25:0), PC (22:0), PE (29:0), PE (34:1), dMePE (15:0/16:1), PE (31:1), dMePE (15:1/15:0), PG (34:2), and PC (11:0/11:0) were identified as the most abundant lipid molecular species in S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C. The increase of PG content contributes to the construction of membrane lipid bilayer and successfully maintains membrane integrity under cold stress. S. putrefaciens cultivated at low temperature significantly increased the total unsaturated liquid contents but decreased the content of saturated liquid contents.

Development of a Novel Method for Rapid Discrimination between Wild and Farmed Sea Bream

A simple method based on direct sampling analysis, coupled with a time of flight mass spectrometer, was developed to discriminate between wild and farmed sea bream on the basis of the docosahexaenoic and arachidonic fatty acid ratio. Good precision in repeatability and reproducibility (relative standard deviation < 15%) was obtained. The fatty acid ratios of the two types of fish were statistically significant (Student's t < 0.001). The use of a simple, rapid, and cost-effective tool could aid in the detection of commercial fish fraud, increase the number of controlled samples, and strengthen control along the entire commercial chain.