Frozen food must be thawed before consumption or processing, and the quality after thawing is not only dependent on the freezing process, but also closely related to the defreezing process. In order to ensure the food industry access to high quality raw materials, good quality food should be kept in good quality after thawing.
Microwave Thawing Successful Case of Pseudosciaena Crocea
The traditional freezing and thawing methods take a long time, consume a lot of energy, and the food quality decreases greatly after the freezing and thawing, which cannot meet the higher and higher living requirements of consumers. As a result, many non – thermal technologies emerge. Non-thermal technology is to reduce the input or output of heat in the food processing process. It includes physical non-heat treatment and biochemical non-heat treatment, specifically, such as electric field, magnetic field, microwave radiation, high pressure, etc. Among them, microwave thawing has the advantages of fast heating speed, strong penetration, uniform heating, selective heating, energy saving, high efficiency and good quality of thawed fish. The research on the method of microwave thawing aquatic products is of great significance to the development of aquatic industry.
Fujian ningde is the hometown of large yellow croaker, derived a lot of large yellow croaker deep processing enterprises. Mr. Shao, whose aquatic products processing plant was defrosting with standing water, is polluting and wasting water resources, plans to introduce a more advanced microwave defrosting equipment.
Pseudosciaena Crocea
The experimental samples were FCL three-layer frozen large yellow croaker at -18℃ and were thawed using a special microwave defrosting equipment of 20kw and 915HZ. Microwave experiments were conducted at 300w, 650w and 1000w respectively. Set it to 5 minutes.
microwave defrosting equipment
Under different power conditions, in the process of microwave thawing, it takes a short time for frozen fish to rise from the initial temperature to -5 ℃, and a longer time for frozen fish to rise from -5 ℃ to 0 ℃, and continue heating after reaching 0 ℃. The temperature rose sharply. The reason for this phenomenon is that the temperature of frozen fish from -18℃ to -5 ℃ requires low energy, which can be completed within 2~3 minutes after microwave heating. However, it takes a lot of energy to rise from -5 ℃ to 0 ℃, which takes 1.5~3 times as long as the temperature of fish rises from -18 ℃ to -5 ℃. However, once the temperature reaches 0 ℃, the microwave energy required for each temperature rise of 1 ℃ will be significantly reduced. After that, the risk of overheating of the fish will increase. After thawing to 0 ℃, continue to heat, the body temperature of the fish will rise sharply. After reaching 0 ℃, the ice on the surface of the fish melts into water, and the absorption capacity of water to microwave is much greater than that of ice, which is the reason for the sharp rise of the temperature of the fish, so the phenomenon of fish body maturation is easy to occur. According to the selected power, it can be seen that the greater the power, the faster the thawing speed, but at the same time the thawing effective time period (thawing effective time period refers to -5~4 ℃) is shorter. The linear pattern of temperature rise is stronger.
When the fish were defrosted by microwave, the ice on the surface had some effect on the defrosting time, but not much. There is little difference in thawing temperature at the same thawing time point with different hanging ice thickness.Therefore, ice on the surface of the fish has little effect on the absorption of microwave. However, hanging ice can extend the effective period of thawing. With the increase of the thickness of hanging ice, the effective period of thawing will be longer. The reason for this is that ice absorbs microwaves much less than fish, and the ice on the surface of the fish holds the heat during thawing.
According to the conclusion of the experiment, it is necessary to accurately control the microwave power and choose the appropriate thawing power and time according to the thickness of the ice layer of the fish to reach the 1~2℃ after thawing required by the customer.
The microwave defrosting equipment of 20kw can defrost large yellow croaker with the capacity of 500kg per hour according to the current production of customers.Absolutely.
站点标题 