解冻损失约束下罗非鱼冻结效率控制参数优化研究

Optimization of Control Parameters of Tilapia Freezing Efficiency under Thawing Loss Constraint

速冻方式不同对鱼肉温降速率、均匀性以及解冻后品质的影响不同,最佳速冻方式选取已成为行业内提升鱼类速冻效率与维持鱼肉品质的主要方式之一。以罗非鱼为例,结合3D扫描逆向建模与计算流体力学数值模拟等技术直观获取冷风式速冻、氯化钠和氯化钙浸渍速冻方式下罗非鱼温度时空分布规律,并通过与实验值比较验证模拟结果的准确性与可靠性,综合对比分析不同速冻方式对罗非鱼冻结速率、均匀性以及水分流失的影响规律,确定最佳速冻方式并提出优化设计方案。研究结果表明,温度模拟值与实测值最大偏差为1.81℃,最大均方根误差与平均绝对百分比误差分别为1.017℃、18.9%,且冻结过程罗非鱼温度降至-15℃时,3种速冻方式所需冻结时间模拟值与实测值最大相对偏差仅为6.89%。其次,氯化钠和氯化钙两种浸渍速冻方式下罗非鱼冻结速率基本相同,相比冷风式速冻冻结时间约降低73%,冻结均匀性提升10~40倍。两种浸渍速冻方式下罗非鱼解冻后水分流失率仅为3.89%和3.92%,分别比冷风式速冻方式降低10.37%和9.68%左右。最后,提出了一种氯化钠液流化速冻方式优化方案,通过综合考虑冻结速率、均匀性及能耗确定最佳流速为2.5 m/s,且相比鱼体头朝入口水平放置与竖直放置,鱼体背朝入口水平摆放方式的冻结效率最优。

Different quick-freezing methods have different effects on the temperature drop rate,uniformity and quality of fish meat after thawing,so that the selection of the best quick-freezing method has become one of the main ways to improve the quick-freezing efficiency of fish and maintain the quality of fish meat in the industry.Taking tilapia as an example,combined with 3 D scanning inverse modeling and computational fluid dynamics numerical simulation and other technologies,the temporal and spatial distribution laws of tilapia temperature under cold-air quick-freezing,sodium chloride and calcium chloride quick-freezing were intuitively obtained.The accuracy and reliability of the simulation results were verified by the comparison of the simulation results.The effect of different quick-freezing methods on the freezing rate,uniformity and water loss of tilapia was comprehensively compared and analyzed,and the optimal quick-freezing method was determined and an optimal design scheme was proposed.The results showed that the maximum deviation between the simulated temperature and the measured temperature was 1.81℃,the maximum root mean square error and the average absolute percentage error were 1.017℃and 18.9%,respectively.When the temperature of tilapia dropped to-15℃during freezing process,the maximum relative deviation between the simulated freezing time and the measured value was only 6.89%.Secondly,the freezing rate of tilapia under the two immersion quick-freezing methods of sodium chloride and calcium chloride was basically the same.Compared with the cold-air quick-freezing method,the freezing time was reduced by about 73%,and the freezing uniformity was improved by about 10 to 40 times.Thirdly,the water loss rate of tilapia after thawing under the two immersion quick-freezing methods was only 3.89%and 3.92%,which were 10.37%and 9.68%lower than those of the cold-air quick-freezing method,respectively.Finally,an optimization scheme of sodium chloride hydrofluidization freezing method was proposed.By comprehensively considering the freezing rate,uniformity and energy consumption,the optimal flow rate was determined to be 2.5 m/s.The freezing efficiency was optimal when the fish was placed vertically,and the fish was placed horizontally with its back to the entrance.