Odor-active compounds contributing to the characteristic aroma of shrimp cooked whole, including shells and viscera

Shrimps and prawns are known to generate a characteristic and pleasant aroma when cooked whole, including their shells and viscera. This study investigated this characteristic aroma of whole-roasted shrimp using Argentine red shrimp (Pleoticus muelleri). Shrimps were roasted in an oven, and the aroma changed upon the usage of whole shrimp. The aroma attributes of “roasted” and “rich” were significantly improved. We performed an analysis of volatile compounds to identify the contributors to roasted and rich aromas and identified 17 odor-active compounds. Heterocyclic compounds including pyrazines, thiazolines, and thiazoles were major contributors to the aroma of whole roasted shrimp. In aroma extract dilution analysis, 2,6-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, 2-acetyl-2-thiazoline, methional, 2-acetylthiazole, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine, and indole were detected with higher flavor dilution factors than were other odor-active compounds. Furthermore, sensory evaluation analysis confirmed that pyrazines contributed to the roasted aroma, and thiazolines and thiazoles contributed to both the roasted and rich aromas. In conclusion, pyrazines, thiazolines, and thiazoles derived from shrimp shells or viscera were the major contributors to the characteristic aroma of whole roasted shrimp and strongly influenced the aroma impression of shrimp dishes.