Comparison of supercritical CO₂ drying with Hot Air and Freeze Drying for Shrimp preservation

Supercritical CO₂ drying is a promising nonthermal method for preserving seafood while enhancing its safety and shelf life. This study aimed to develop a low-temperature drying process using supercritical CO₂ (CO₂) and compare the resulting shrimps with those dried by hot air (60°C) (AC) and freeze-drying (L) over a 4-month shelf life. Physical properties, including water activity, weight change, shape, texture, pH, and color, were evaluated monthly. Moreover, after the first month of storage, a panel of 80 consumers (53% women) evaluated the rehydrated products after rehydration, in comparison with a reference defrosted sample (SC). The aim was to investigate the impact of drying methods on shrimp’s overall acceptability and sensory profile as assessed through a CATA questionnaire focusing on visual, olfactory, and tactile attributes. Texture analysis revealed that CO₂-dried shrimp exhibited greater hardness and structural integrity across all time points, while freeze-dried shrimp demonstrated significantly higher springiness in the second month (1.54±1.11). AC samples generally had lower structural stability. By the end of the shelf life, CO₂-dried shrimp remained the firmest (hardness 8566±2568.35), though springiness showed no significant differences among samples. Regarding sensory results, the drying method significantly influenced consumer perception and acceptability of shrimp. The L and SC samples received the highest liking score (6.75 and 6.64, respectively on a 9-point categorical scale) while CO₂ and AC were the least appreciated (3.30 and 3.64 scores). In terms of sensory attributes, the analysis highlighted clear differences in visual, olfactory, and textural qualities depending on the preservation method: the L and SC shrimp were described as pink, fleshy, and having a fresh fishy odor; the CO₂-dried shrimp were perceived as rough and fibrous, with ferrous and putrid notes; and AC-dried shrimp were described as dry, with a rancid, smoky odor. To conclude, CO₂ drying preserved shrimps’ hardness but led to lower sensory acceptance, whereas freeze-dried shrimps maintained better texture and appeal, making it a preferable method for quality retention.