不同冷链物流过程对金枪鱼品质及组织形态的影响

摘要

为研究物流过程中温度变化对金枪鱼品质及组织形态的影响，试验模拟5种不同物流过程，测定金枪鱼肉感官、色差、持水力、质构以及肌纤维间隙。结果表明，超低温冻藏大目金枪鱼肉的品质受物流过程中温度变化影响显著，储运、销售过程始终保持在-55℃的完整冷链下能够使金枪鱼肉保持良好品质；随着储运过程中温度变化次数增多、幅度增大，鱼肉劣化显著，其中，经2次-18℃运输的金枪鱼肉在冻藏末期组织松散、肌纤维间隙达17.20μm，在4℃家用冰箱中贮藏12 h后感官评分、红度值、持水力、硬度和咀嚼性分别为-0.81、5.2、53.08%、1.128 N和58.03，其质量甚至低于物流过程始终保持在-18℃而不产生温度变化的鱼肉。若运输过程不具备超低温冷藏车，仅靠超低温贮藏并不能减缓鱼肉品质劣变，此时应适当调节贮藏温度，尽量避免储运期间的温度变化；相较于2℃冷藏销售，-18℃冷冻柜销售能够使金枪鱼肉保持较好品质。研究结果可为金枪鱼储运和销售提供参考。%The process of cold chain logistics including storage, transportation, selling, and other steps, requires the temperature to be kept at an ultra-low degree of-55℃at all times-. However, because there is a current lack of mechanical cryogenic transportation vehicles in China that meet this requirement, ordinary refrigerated trucks with a temperature of only-18℃ are widely used for tuna transport. The aim of this study is to investigate the effects of variations in storing temperature and selling models on the quality and microstructure of tuna (Thunnus obesus). In this paper, four diverse situations of transportation and storage were performed to simulate:complete ultra-low temperature cold chain (-55℃), normal cold chain (-18℃), and tuna stored at -55℃ but transported afterwards at -18℃ once and twice. Three different sales models were also designed: ultra-low temperature refrigerator sale (-55℃), refrigerated display case sale (2℃) and freezer sale (-18℃). In these situations and models, changes in sensory evaluation, color value, water holding capacity, and texture were assayed periodically, and the gap between muscle fibers was measured by making paraffin sections at the end of frozen storage. The results showed that the quality of bigeye tuna stored at ultra-low temperature was significantly affected by temperature changes in the logistics process. Whereas the quality of tuna can be kept well under a complete ultra-low temperature cold chain of-55℃during transportation and sale, temperature changes led to a decrease of sensory score, meat color (a* value), water holding capacity, hardness, and chewiness. The more the frequency and range of temperature changes, the greater the deterioration would be. When stored at-55℃but transported at-18℃twice before being stored at 4℃in domestic refrigerators for 12 hours, sensory score, meat color (a*value), water holding capacity, hardness and chewiness of tuna were-0.81, 5.2, 53.08%, 1.128N and 58.03, respectively. And, the quality of tuna in the above situation was lower than when it was maintained at-18℃all of the time. For microstructure, tuna which was kept in a complete ultra-low temperature cold chain had a smaller muscle fiber gap, which was only 7.81μm, and the muscle bundles were relatively tight. However, tuna which was kept under a completely normal cold chain and transported afterwards at -18℃ twice, had more loose organizational structures, and the gap between muscle fibers were 10.37μm and 17.20μm, respectively. Experimental results showed that the lack of ultra-low temperature refrigerated trucks would result in a lower quality of tuna. All in all, temperature variation in transportation and storage should be avoided. Storage temperature should be appropriately increased when ordinary refrigerated trucks are applied for transportation. As compared with those displayed under -18℃, tuna sales under the condition of 2℃ could be favored by the consumers in the first 12 hours due to its color after thawing. However, the quality of the meat color (a*value), water holding capacity, hardness and chewiness was not better. In general, this study provided references for retaining the freshness of tuna in different stages of storage, transportation and sales.