Factor de qualitat durant el procés IQF de congelació

Quality Factor During Freezing IQF Process!

1. The effect of cooling medium temperature

Under the process conditions of IQF Freezing, the lower the temperature of the cooling medium, the faster the product freezes under the same conditions. At present, according to the specific situation in China, most of the ammonia is used as a refrigerant, and the evaporation temperature is generally selected between -35 and -45 °C. Under the IQF process, if a forced air continuous freeze is used, the temperature of the cooling medium is also related to the frosting speed of the evaporator. That is, when the evaporating frost layer reaches a certain thickness, the temperature of the cooling medium is correspondingly increased due to a decrease in the heat transfer effect. Therefore, in order to ensure the quality of the frozen, it should be done in time to defrost.

2.The effect of air flow rate

Sota el procés de congelació IQF, el flux d'aire és el principal factor que afecta el valor del coeficient exotèrmic. Per tant, un augment adequat del cabal d'aire pot augmentar el grau de congelació final. Per exemple, les mongetes verdes comunes es congelen a l'aire estàtic de -30 °C, que triguen unes 2 hores. A la mateixa temperatura, el cabal d'aire augmenta a 4.5-5 m/s i el temps de congelació és de només 10 minuts.

En determinades condicions, el canvi entre la velocitat de congelació i el cabal d'aire no és lineal, de manera que el cabal d'aire s'ha de determinar de manera exhaustiva des d'un punt de vista econòmic.

3. The effect of freezing termination temperature

The freezing termination temperature is lower than the storage temperature (-18 ° C), which is beneficial to maintain the structure under rapid freezing. If the freezing termination temperature is higher than -18 °C, the unfrozen water inside the vegetable tissue will generate large ice crystals, which will result in the destruction of the tissue structure and the increase of juice loss during thawing, which will affect the nutritional value and flavor of the product. If you interested lear more about freezing IQF, please click gf-machine