Characterization of aroma profiles and aroma-active compounds in high-salt and low-salt shrimp paste by molecular sensory science

Flavor characteristics of raw shrimp, high-salt and low-salt shrimp paste were evaluated and compared by sensory analysis, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In addition, aroma profiles and aroma-active compounds in these three samples were analyzed by solvent-assisted flavor evaporation-gas chromatography-olfactometry-mass spectrometry (SAFE-GC-O-MS). Results of sensory evaluation revealed that these three samples showed significant differences in sensitivity to the W2W, W2S, W1S and W1W sensors of the electronic nose (p < 0.05), which represent organic sulfides, alkane aromatic compounds, short chain alkanes, and sulfides, respectively. Assessment of sensory parameters indicated tha high-salt shrimp paste had a strong roasted and meaty aroma, while low-salt shrimp paste showed an umami aroma more similar to raw shrimp. A total of 118 volatile compounds were identified using the three afore-mentioned gas chromatography methods. Among them, 37 aroma-active compounds were detected by GC-O. High-salt shrimp was shown to contain more acids, aldehydes and heterocyclic compounds, which resembled cheese, roasted and meaty aromas. In contrast, low-salt shrimp paste contained more esters, which was similar to the umami aroma profile of raw shrimp. Interestingly, pyrazines were only produced in fermented shrimp paste samples, suggesting that they were produced during the fermentation process and they may contribute unique roasted and meaty aromas, which were important for the overall aroma characteristics of shrimp paste.