Analyzing the Flavor Compounds in Chinese Traditional Fermented Shrimp Pastes by HS-SPME-GC/MS and Electronic Nose

Shrimp paste is a type of condiments with high nutritional value.However,the flavors of shrimp paste,particularly the non-uniformity flavors,have limited its application in food processing.In order to identify the characteristic flavor compounds in Chinese traditional shrimp pastes,five kinds of typical commercial products were evaluated in this study.The differences in the volatile composition of the five products were investigated.Solid phase micro-extraction method was employed to extract the volatile compounds.GC-MS and electronic nose were applied to identify the compounds,and the data were analyzed using principal component analysis(PCA).A total of 62 volatile compounds were identified,including 8 alcohols,7 aldehydes,3 ketones,7 ethers,7 acids,3 esters,6 hydrocarbons,12 pyrazines,2 phenols,and 7 other compounds.The typical volatile compounds contributing to the flavor of shrimp paste were found as follows:dimethyl disulfide,dimethyl tetrasulfide,dimethyl trisulfide,2,3,5-trimethyl-6-ethyl pyrazine,ethyl-2,5-dimethyl-pyrazine,phenol and indole.Propanoic acid,butanoic acid,furans,and 2-hydroxy-3-pentanone caused unpleasant odors,such as pungent and rancid odors.Principal component analysis showed that the content of volatile compounds varied depending on the processing conditions and shrimp species.These results indicated that the combinations of multiple analysis and identification methods could make up the limitations of a single method,enhance the accuracy of identification,and provide useful information for sensory research and product development.

Application of electronic nose and GC-MS for detection of strawberries with vibrational damage

Objectives: This study evaluated the potential of using electronic nose (e-nose) technology to non- destructively detect strawberry fruits with vibrational damage based on their volatile substances (VOCs). Materials and methods: Four groups of strawberries with different durations of vibrations (0, 0.5, 1, and 2 h) were prepared, and their e-nose signals were collected at 0, 1, 2, and 3 days after vibration treatment. Results: The results showed that when the samples from all four sampling days during storage were used for modelling, both the levels of vibrational damage and the day after the damage happened were accurately predicted. The best models had residual prediction deviation values of 2.984 and 5.478. The discrimination models for damaged strawberries also obtained good classification results, with an average correct answer rate of calibration and prediction of 99.24%. When the samples from each sampling day or vibration time were used for modelling, better results were obtained, but these models were not suitable for an actual situation. The gas chromatography-mass spectrophotometry results showed that the VOCs of the strawberries varied after experiencing vibrations, which was the basis for e-nose detection. Limitations: The changes in VOCs released by other forces should be studied in the future. Conclusions: The above results showed the potential use of e-nose technology to detect strawberries that have suffered vibrational damage.