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Journal of Zhejiang University SCIENCE B
ISSN 1673-1581(Print), 1862-1783(Online), Monthly
2022 Vol.23 No.7 P.578-586
Assessment of quality deviation of pork and salmon due to temperature fluctuations during superchilling
Abstract: Superchilling is an emerging technology for meat preservation; however, the temperature changes during the process have been commonly ignored. Thus, the effects of temperature fluctuations on meat quality during superchilling are yet to be evaluated. In our study, pork loins and salmon fillets were stored for several days (0, 8, 15, 23, and 30 d) under different temperature fluctuations based on -3.5 °C as the target temperature. The results showed that after 15 d of superchilling storage, the values of total volatile basic nitrogen, total viable count, and lipid oxidation were significantly (P<0.05) altered in the ±2.0 °C fluctuation group compared with the constant temperature group. On the contrary, there was no significant difference in these parameters between the ±1.0 °C fluctuation group and the constant temperature group after 30 d of storage. In addition, irregular temperature changes significantly accelerated the modulation of various indicators. In brief, temperature fluctuations and irregular temperature changes accelerated the destruction of muscle structural integrity, increased the water loss, gradually widened the water loss channels, and thereby reduced the edibility by accelerating the spoilage of meat.
Key words: Pork; Salmon; Superchilling; Temperature fluctuation; Meat quality
机构：1同济大学，机械与能源工程学院，中国上海，201804；2中航工业航空机电系统综合航空科技重点实验室，中国南京，210061
目的：偏转板伺服阀前置级二维流场模型因忽略了射流在射流盘厚度上的拓展现象，无法准确地描述偏转板伺服阀前置级流场结构。为了更加精确地描述流场结构并计算前置级的静态特性，并有利于优化偏转板伺服阀前置级的结构参数，本文提出一个符合真实状态的三维流场数学模型。
创新点：1.在前置级三维流场数学模型中，将流场分为五个区域，考虑射流在空间上的三维拓展。2.运用三维紊动射流描述自由射流区流场结构，并提出该区域的射流速度分布表达式。3.在压力恢复区提出射流卷吸模型，并建立起接收腔射流流量和恢复压力的耦合关系。
方法：1.通过理论分析，建立前置级流场各阶段的数学模型（图2~9），得到前置级静态特性的理论分析方法（图11和12）；2.通过实验研究某型前置级在不同供油压力下的断载压力特性，验证本文提出的数学模型在计算静态特性时的准确性（图15）；3.通过仿真模拟，分析前置级自由射流区射流截面的速度分布以及接收腔内的射流影响因素，验证三维射流模型和射流卷吸模型的可行性和有效性（图17）。
结论：1.前置级流场内的射流属于三维射流。本文采用的三维射流可以更加准确地描述流场的结构（图2）。2.自由射流区的等速度线接近直槽口形，可近似用矩形等速度线描述（图17），并且接收腔内的射流流量和恢复压力等参数存在耦合关系，可以用本文提出的卷吸射流模型描述。3.在不同供油压力下的前置级无因次断载压力基本一致，基于三维流场模型得到的前置级静态方法计算结果准确（图15），可以为前置级的结构优化提供理论支持。
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DOI:
10.1631/jzus.B2200030
CLC number:
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On-line Access:
2022-07-06
Received:
2022-01-16
Revision Accepted:
2022-04-10
Crosschecked:
2022-07-06