Effects of Thawing Methods on Eating Quality of Salted Crab

In order to investigate the effects of different thawing methods on the eating quality of frozen salted crab and further to select the best thawing method, this study compared and analyzed the thawing curves using five thawing methods including low temperature thawing, room temperature thawing, running water thawing, ultrasonic thawing and pulsed magnetic field assisted thawing, and tested the quality attributes of the thawed samples by sensory evaluation and electronic tongue. Besides, the contents of proteins and their degradation products as well as flavor nucleotides were measured. The results showed that ultrasonic and pulsed magnetic field assisted thawing were the most time-saving (10.4 and 26.2 min, respectively), and low temperature thawing was the most time-consuming (312.6 min). The sensory scores for color, texture and odor of crab meat thawed by pulsed magnetic field were the highest, and the sensory score for taste of crab meat thawed by ultrasonic was the highest. The results of electronic tongue showed that the quality of salted crab meat treated by low temperature thawing, pulsed magnetic field assisted thawing and ultrasonic thawing was closer to each other, but significantly different from that of salted crab meat treated by running water thawing and room temperature thawing. The moisture content of salted crab meat thawed by ultrasound was the highest (84.37%), while the proteolysis index of salted crab meat thawed by pulsed magnetic field was the lowest (13.83%), and salted crab meat thawed by flowing water had the lowest moisture content (77.36%) and the highest proteolysis index (16.64%). The total free amino acid content of low-temperature thawed salted crab meat was the highest (2885.78 mg/100 g). The contents of glutamate, glycine and alanine in salted crab meat thawed by pulsed magnetic field and ultrasonic were similar (97.50 vs 92.30 mg/100 g, 665.80 vs 642.40 mg/100 g, and 487.20 vs 490.50 mg/100 g, respectively, which were significantly higher than those of salted crab thawed by the other three methods. The different thawing methods had significant effects on flavor nucleotides in salted crab meat. Higher contents of flavor nucleotides were detected in salted crab meat thawed by ultrasound and pulsed magnetic field, with the highest equivalent umami concentration (EUC) being found in pulsed magnetic field thawed crab meat (44.38 g/100 g). Therefore, pulsed magnetic field thawing was the most suitable thawing method for frozen salted crab.