Effects of Different Harvest Seasons on the Physicochemical Properties and Volatile Flavor Compounds of Hot-air Drying Abalone Haliotis discus hannai and H. discus hannai ♀× H. fulgens ♂

To investigate the effects of different harvesting seasons on dried abalone (Haliotis discus hannai, DD) and hybrid abalone (Haliotis discus hannai ♀×H. fulgens ♂, DF), samples were harvested in autumn 2022 and spring 2023 for hot-air drying processing. Comprehensive analysis was conducted to evaluate nutritional composition, amino acid, and fatty acid profiles. The rehydration rate and post-rehydration textural properties were systematically assessed. Volatile flavor compounds were analyzed using HS-SPME-GC-MS. Results demonstrated that autumn dried abalone exhibited significantly higher collagen content (6.79%~8.45%), α-linolenic acid (0.77%~0.98%), and arachidonic acid (14.57%~14.85%) (P<0.05), whereas spring groups showed elevated taurine levels (13.16~16.20 mg/g) and DHA proportions (1.17%~1.28%) (P<0.05). Both autumn and spring DD dried abalone had higher carbohydrate (37.92~46.90 mg/g) and Phe (6.72~7.15 mg/g) content compared to DF dried abalone (P<0.05). Rehydration experiments showed that the rehydration rate of DD dried abalone leveled off after 48 hours, while DF dried abalone continued to increase, with no significant seasonal effect on the rehydration rate (P>0.05). Textural analysis identified spring dried abalone had higher adhesiveness (1.45~1.59 gf×sec) and resilience (0.32~0.40) compared to autumn dried abalone (P<0.05). HS-SPME-GC-MS identified a total of 22 important volatile compounds, spring dried abalone had higher aldehyde concentrations (1652.92~1704.37 μg/g) with heptanal (367.53~610.92 μg/g) and nonanal (439.25~486.85 μg/g) being the predominant compounds. In addition, 2-decanone, a ketone compound, was specifically detected in spring dried abalone (61.77~81.65 μg/g). In contrast, the total amount of alcohols in autumn dried abalone (3730.04~3757.51 μg/g) was significantly higher than in spring, with 1-octen-3-ol (2210.80~2260.24 μg/g) being the highest among all compounds (P<0.05). Odor activity value (OAV) analysis indicated that compounds such as 1-octen-3-ol, trans-2-octen-1-ol, nonanal, and heptanal had high OAV values and were the key flavor compounds in dried abalone. In conclusion, there are differences in the nutritional composition and rehydration rate between DD and DF dried abalone, with dried abalone from spring harvests showing superior texture and flavor characteristics.