For each fish species the shelf life in Fig .I is given as a shaded area depending on PPP factors which have to be evaluated in each ca. Traditionally, and as a general rule, temperatures below freezing point are not ud due to visual changes and "frost damage". With additional preervation, such as Modified Atmosphere Packaging, shelf lide can be incread providing the temperature is kept low . The additional methods are ideal for filleted and procesd fish mainly ud for domestic consumption.
clarify Distribution of fresh food,nationally and internationally, requirers a well functioning cold chain from harvest to the consumers. Most industrialized countries have cold chains where the different gments arecontrolled by producers ,industry, distributors, improters and food chains .Studies and measurements of cold chains in most links, but esppecially intransport and sales equipment. Errors and lack of chilling in transfer operations or transport equipment are alsommon.
Improved chilling - superchilling
In traditional chilling procces, nofreezing should take place on the surfaces of products .As a result, the driving force for heat removal is very low. For large/thick products the internal heat transfer is very slow due to low thermal conduction path and low thwemal conuctivity. This makes traditional industrial chilling very time-consuming and challenging in modern in-line production. As an example ,salmon of common size (4-5 kg) can be chilled in RSW at -1million是什么意思℃ from 15℃ to 2℃ in about 2h. Slaughter plants with normal capacity of more than 20 ton/h therefore require spacious and challenging arrangements for continuous in-lline chilling. In practice , a significant part of the chilling has to be done after packing in boxs with the u of ice .In addition, ice is also usually required to cure low temperatures in an unreliable cold chain .
The terms "superchilling" and "partial freezing" are ud to describe a process where a minor part of the product's water content is frozen . During superchilling, the temperature of the foodstuff is lowed , ofen 1-2℃ , below the initial freezing point of the product . After initial surface freezing, the ice distribution levels out to
a predefined value and the product obtains a uniform temperature at which it is maintained during storageand distribution .
complex The process of superchilling was described as early as by Le Danois , even though he did not actually u the terms "superchilling" or "partial ice formation". Withsuperchilling technology ,cold is accumulated within the product and rves as a heat sink for eventual ambient heat load . The necessary holding time inside the chilling equipment is shortened compared to traditional chilling, as the ice formed under the surface accumulates heat from the interior of the products after leaving the equilibrium, the product will have a rervoir of coid to absorb heat from the surroundings without altering the product temperature too much . Both the advantages are ud in industrial applications today . Furthermoer, veral cutting process inthe food producing industry depend on a partial frozen surface in order to get straight cuts and a stable production.
At superchilling temperatures, most microbial activity terminaes or is inhibited. C
hemical and physical chanfes may progress ,and in some cas even accelerate. In the literatures, repoets on superchilling have mainly involved fish and poultry . The main conclusions for superchilled food of at least 1.4-4 times compared to traditional chilling . Ice-forming and recrystallization can cau microstructural changes to foods tissue during freezing, resulting in cell dehydration ,drip loss and tissue shrinkage during thawing . Food characteristics such as PH, ionic strength , concentration of dissolved gas , viscosity , oxidation-reduction potential and surface tension couid also be altered , leading to changes in enzymatic activity and protein denaturation .
As early as the 1950s , Portugue deep-a trawlers exploited superchilling on a large scale in vesls . Catches were stored in ice on shelves and sub-cooled to -2℃ to -5℃ by circulating brine through coils . The technology combined rapid chilling in ice with effcient and controlled cintact superchilling. The storage method incread shelf life by up to 11 days for some applications .完型填空
每个鱼类货架寿命图。我是在每一种情况下一个阴影面积取决于购买力平价因素加以评估的。传统上，并作为一般规则，温度低于冰点是由于没有使用视觉变化和“冻害”。额外的preervation，如气调包装，可以增加货架的提供，保持温度低。这些额外的理想方法用于剔骨和加工鱼，主要用于国内消费。
分布的新鲜食品，在国内和国际，requirers运作良好的冷链从收获到消费者。大多数工业化国家有冷链不同环节控制的生产者，行业，经销商，进口商和食物链。研究和测量的冷藏链最链接，但esppecially intransport销售设备。错误和缺乏低温传输操作或运输设备immortalityalsommon。
改进的莫言作品蛙冷却-冰温
在传统冷却种过程的同，＃应在产品表面。因此，动力散热很低。大型厚产品的内部热量传递是非常缓慢的，由于低的热传导路径和低thwemal conuctivity。这使得传统的工业冷却很费时和艰巨的现代生产线。作为一个例子，鲑鱼常见尺寸（4 - 5公斤）能被冷冻在- 1℃点焊中从15到2℃℃约2小时。屠宰厂正常生产能力超过20吨/小时，因此需要宽敞的和具有挑战性的安排，连续in-lline冷。在实践中，有很大一部分的冷了后包装盒的使用冰。
此外，冰通常也需要安全可靠的低温冷藏链。
术语“冰温江西师大自考网”和“部分冻结”是用来描述一个过程，一小部分产品的水分冻结。在冰温，温度降低的食品，通常1 - 2℃，低于最初的冰点的产品。经初步表面冻结，冰分布水平到一个预定义的价值的产品获得均匀的温度是保持在存储分配。
天津网络培训冰温的过程被称为早在danois乐，尽管他实际上并没有使用术语“冰温”或“部分冰的形成”acquiesce。withsuperchilling技术，冷积累的产品和服务作为散热最终环境热负荷。所需的时间内的冷却设备缩短相比传统的冷却，由于冰下形成的表面积聚热量从内部的产品后留下的平衡，该产品将有一个储冷吸收热量从周围没有改变产品的温度过高。这些优点是用于工业应用的今天。furthermoer商务英语专业课程，几个切削过程在食品制造工业取决于局部冷冻表面为连续和稳定的生产。
