快速鉴别冰鲜和解冻石斑鱼的研究

Nondestructive Physical Methods Differentiates Unfrozen from Frozen-thawed Grouper(Epinephelus drummondhayi)

运用伏安法测定不同频率下冰鲜和解冻石斑鱼的阻抗,当电流频率从1kHz增大到16kHz时,冰鲜和解冻石斑鱼的阻抗均随频率的增大而减小。冰鲜1、3、5、7天石斑鱼的阻抗相对变化值(Q)值分别为40.0%、30.7%、25.0%、21.9%;而在-20℃冷冻2天解冻后第一天的石斑鱼,其Q值为16.2%,在-30℃冷冻2天解冻后第一天的石斑鱼,其Q值为13.4%。对比可知,冰鲜鱼的Q值明显大于解冻鱼,所以,依据Q值>20%或<20,可以区分冰鲜和解冻石斑鱼。

Electric conduction property of unfrozen and frozen-thawed grouper was studied by measuring their impedances under different frequencies. The impedances varied as frequency change. The change ratio of impedances（Q value） of the unfrozetx grouper on the 1st, 3rd, 5th and 7th day were 40.0%, 30.7%, 25.0%, 21.9% respectively. The Q value of the frozen-thawed grouper which had been frozen at the temperature of -20℃ for two days was 16.2% on the first day it thawed. The Q value of the frozen-thawed grouper which had been frozen at the temperature of -30℃ for two days was 13.4% on the first day it thawed. Although impedances of unfrozen and frozen-thawed grouper decreased as frequencies increased, change ratio of impedance of unfrozen grouper was evidently more than that of frozen-thawed ones. Therefore, it is feasible to identify unfrozen and frozen-thawed grouper using change ratio of their impedances compared with 20%.