Background Litopenaeus vannamei is highly valued for its rich nutritional profile and delicious taste. Drying is one of the primary processing methods for shrimp; however, traditional constant-temperature drying has notable limitations. Low-temperature drying often fails to develop desirable flavors, while high-temperature drying tends to cause texture hardening and other quality defects, thereby restricting the overall quality improvement of the product.

Objective This study aimed to investigate the effects of different variable-temperature drying conditions on the quality of semi-dried seasoned roasted shrimp, identify the optimal drying process, and develop a product with excellent color, texture, and flavor, thereby providing technical references for the development of semi-dried aquatic products.

Methods Using L. vannamei as the raw material, the semi-dried seasoned roasted shrimp were processed using a combined low-temperature and high-temperature drying approach. The effects of three drying conditions (60 ℃−2 h/160 ℃−20 min, 60 ℃−2 h/180 ℃−20 min, 60 ℃−2 h/200 ℃−10 min) on color, texture (hardness and shear force), shrinkage rate, volatile compounds, taste characteristics, flavor nucleotides, and overall sensory quality of semi-dried seasoned roasted shrimp were systematically evaluated.

Results Compared with fresh shrimp (Raw), the moisture content (MC) and water activity (A_w) of the semi-dried roasted shrimp decreased significantly (P<0.05), while the shrinkage rate, hardness, and shear force increased significantly (P<0.05). The texture, color, and flavor were also significantly enhanced. Among the different drying conditions, the semi-dried seasoned roasted shrimp treated at 160 ℃ and 180 ℃ for 20 min exhibited closely resembled textural properties and flavor profiles. The semi-dried seasoned roasted shrimp treated at 180 ℃ for 20 min exhibited the most prominent volatile flavor and taste profile. It was primarily characterized by pyrazine volatile compounds, such as 2, 5-dimethylpyrazine, 3-ethyl-2, 5-dimethylpyrazine, and 2-ethyl-5-methylpyrazine, which contributed meaty, roasted, and nutty aromas. Additionally, it possessed high contents of inosine monophosphate (IMP) and adenosine monophosphate (AMP) (601.54 and 287.69 mg/100 g, respectively), along with high umami and richness response values, and received the highest sensory score (16.10).

Conclusion For the variable-temperature drying process, the optimal condition was determined to be drying at 60 ℃ for 2 h combined with drying at 180 ℃ for 20 min. This protocol enabled the production of semi-dried seasoned roasted shrimp with desirable texture and enhanced flavor.