Frozen squid "returning frost" refers to the frozen packaged food. After storage for a period of time, there is a clear phenomenon of free frost crystals in the package. After the frozen food packaging is completed, there is only food in the package. After being placed for a period of time, frost crystals appear in the frozen food packaging bag, which not only seriously affects the appearance quality, but also causes the weight of the food to be reduced and the quality to be degraded.
First, the source of frost crystals in food packaging bags
First of all, these frost crystals do not intrude from the outside of the packaging bag, because the polyethylene film for food packaging has a good water vapor barrier effect, and the external water vapor cannot enter the packaging bag without a pressure difference. The frost crystals in the food packaging bag can only come from the food in the packaging bag. Therefore, the appearance of frosting means a reduction in the weight of food or food outside the ice. When there is no packaging or packaging airtightness, this phenomenon is also expressed as "air drying", or "dehydration", or "dry consumption", the essence of which is that the moisture in the food volatilizes from the food to the outside of the food. The moisture eventually condenses on the inside of the package to form frost crystals or condense on the refrigeration tube to form a frost. The frost crystals condensed on the cooling pipe should be cleaned regularly, otherwise it will affect the working efficiency of the refrigeration system.
Second, the main reason for food anti-frost
In order to suppress the frosting phenomenon, most technicians look for the factors affecting the frost in the packaging process. To this end, many companies spend money and energy to improve the environmental conditions of the packaging room, such as installing refrigeration equipment in the packaging room to reduce the temperature of the packaging room, reduce the water temperature of the ice coating, increase equipment and personnel to shorten the packaging operation time, prevent food surface Thawing, etc., but the results of these efforts often fail to effectively solve the problem of frosting. The high ambient temperature in the packaging room, or the long working time, first causes the thawing of the surface of the frozen food. How much influence does this factor have on the “quantity” of the frosting? Is it the main reason for food frosting?
According to expert research and experiments, we have transferred the reason for the frosting of frozen products from the environmental conditions in the packaging room to the cold storage. The stability of the cold storage temperature can reduce the frosting of frozen foods.