Application of low temperature and high humidity air defrosting machine
At present, whether domestic or foreign meat processing plants, the raw meat used to process meat products is mostly frozen meat and fresh meat, and frozen meat accounts for a certain proportion.
Before processing meat products, meat enterprises generally need to thaw frozen meat with microwave thawing machine to the temperature suitable for the process requirements, in order to facilitate the subsequent process (such as dressing, raw material mixing, etc.). According to different thawing methods, the thawing equipment can be divided into: air thawing (static, mobile, pressurized, decompressed), hydrolytic freezing (stationary, flowing, pressurizing, spraying, spraying, low pressure steam), microwave thawing, heating and thawing (hot air, steam, hot water immersion, hot plate contact) and so on. Former meat processors at home and abroad used different thawing methods according to their actual situation.
Microwave thawing is done by microwave heating to thaw frozen meat. In the past, frozen meat was mostly relied on air and water. The two methods are heat transfer from outside to inside. The microwave thawing is not only surface heating, but also internal heating. By microwave thawing, the general 1H can be completed, while the conventional air thawing needs more than 10h.
Because the microwave thawing time is short, it will not give enough time for enzymes or microorganisms to function, and it is not easy to cause meat deterioration, so the quality of microwave thawing meat is better. However, microwave heating is also strong on the surface and weak in the interior, especially in the corner and protrusion, which will produce heating denaturation. In addition, due to the uneven meat tissue, the calorific value of water is significantly higher than that of ice, so there will be a greater temperature imbalance.
There are usually static air, flow and pressurized thawing methods with air as medium. However, although forced ventilation can improve the speed of thawing, it brings about the negative effects of surface drying and quality degradation of thawed products. At the beginning of thawing, because of the large temperature difference between the surface temperature of the thawed product and the air temperature, even if the humidity in the thawing chamber is very low, frost will form on the surface of the thawed product, which can inhibit the occurrence of surface drying.
However, as the thawing proceeds, when the surface temperature is higher than - 2 C, the relative humidity in the room is not very high, drying will occur. The lower the relative humidity, the faster the drying speed. When the relative humidity is 85%, the drying speed is three times as fast as when the relative humidity is 95%, which makes the color of the thawed product worse and the weight loss. Low temperature and high humidity air thawing machine is to use low temperature humidification method, so that high humidity air circulation in low temperature environment, so that the thawing chamber to form high humidity air flow, to avoid the phenomenon of thawing products surface drying.