seafood freeze technology adopt high effective impingement tunnel freezer
The high-efficiency impact quick-freezer developed and produced by First Cold Chain Company
is more suitable for freezing various aquatic products, and the freezing efficiency is higher.
The freezing points of aquatic products are -0.5°C, -0.75°C, -1°C, -1.5°C and -2°C in the order of freshwater fish, brackish water fish, whale meat, migratory marine fish and bottom marine fish. Using the traditional chilled method to reduce the temperature of fish to close to 0 ℃, it can be refrigerated for a short period of time without freezing. There are two kinds of chilled methods: ice storage method and water ice method. ① Ice storage method: evenly spread the crushed ice between each fish layer, and the amount of ice used should include the ice required to cool the fish to close to 0°C and the ice required to maintain this temperature during storage. Generally, the ratio of fish volume to ice volume is about 1:1 when the fish is packed in a refrigerator in a refrigerator with an air temperature of 0-3°C. If there are chilled and bulk fish in the cabin, more ice should be used to fill the gaps. ②Water ice method: immerse the fish in fresh water or sea water with crushed ice, and use a refrigeration device to keep it at 0 to -1°C. Because water is used as a medium, the amount of ice is reduced, usually: the amount of fish : Water volume: Ice volume 1:1:0.5. This method is mainly used for seafood, and seawater must be used, so it is also called cooling seawater to keep fresh. It can prevent fish lipids from being oxidized by air, and can accelerate the death of fish with strong vitality to prolong the rigidity period after death, but the disadvantage is that it can lead to enhanced water absorption and slightly salty taste of fish.
The longest period that chilled aquatic products can maintain freshness is generally 5 days for freshwater fish, 7 days for brackish water fish, 21 days for whale meat, 10 days for migratory marine fish, and 14 days for bottom marine fish. There are also great differences between the different species. Usually based on migratory marine fish, the shelf life of chilled fish is limited to 10 days. For those that need to be preserved for 10 days to one month, the micro-freezing or super-cooling preservation method has been applied, and this method still belongs to the category of refrigeration preservation. It is also divided into ice storage method and water ice method. The former is the amount of fish: the amount of ice is 2:1. It is placed in a cold storage with an air temperature of -5 °C to cool the fish and keep it at 3 °C, and its surface is slightly frozen; the latter is to add salt to seawater, When it reaches 7°Be' at 15°C, it becomes brine with a freezing point of -4.6°C, and is cooled to -4°C with a cooling device, then the temperature of the fish immersed in it is about -3°C, and the surface layer is frozen. . Both of these two methods can be kept fresh for 3 to 4 weeks, but the latter has salty taste infiltration, and the color of the fish is changeable. The low temperature used for micro-freezing and fresh-keeping is just within the temperature range of the maximum ice crystal formation zone (-1 ~ -5 °C) of food, which is most likely to damage muscle cells, and can cause a large degree of protein denaturation (see food preservation), but in Compared with the quality of the following frozen and fresh-keeping products after thawing, it is considered that the effect of the micro-freezing method is still good. Frozen preservation is because the oxidation speed of tuna myoglobin is 1 to 3 times faster than that of mammals, and the temperature effect is particularly obvious. With the improvement of people's quality requirements and the advancement of technology, the temperature of frozen storage is also getting lower and lower, from -18℃-25℃-35℃-50℃-60℃, according to Oto's research, in 6 months In the freezing storage cycle of 100%, the production rate of high iron myoglobin at -35°C is about 33% lower than that at -18°C, and only 2% higher than that at -78v, while the energy consumption is much lower. Therefore, according to the existing situation in China, it is recommended to freeze at -35°C. If the preservation period is to be further extended, a lower freezing temperature is required. In addition, it must be noted that the frozen tuna must also quickly pass through the temperature range of -4℃-7℃, otherwise the muscles will also be easily discolored.
Therefore, in summary, the quick freezing machine is an indispensable quick-freezing equipment for frozen aquatic products.
