Should food processing be done in a quick-freezing cold storage facility or a quick-freezing tunnel?
Quick-freezing cold storage facilities and quick-freezing tunnels are widely used for the rapid freezing of various aquatic products and frozen foods to maximize the preservation of their original nutritional value, color, aroma, and flavor. They are often used in conjunction with low-temperature freezers. Although various physical and chemical changes occur in food during freezing, such as volume reduction, increased moisture loss, protein denaturation, color changes, and alterations in biological and microbial activity, rapid freezing maximizes the reversibility of these changes. So why can rapid freezing methods like quick-freezing cold storage facilities and quick-freezing tunnels restore the original quality of food upon thawing?
Quick-freezing cold storage facilities and quick-freezing tunnels freeze food in an extremely short time, bringing the core temperature of the food to -18°C. This short-duration rapid freezing prevents the formation of large ice crystals between cells and reduces the outflow of intracellular water. This significantly shortens the contact time between concentrated solutes, food tissues, colloids, and various components within the cell tissue, minimizing the harmful effects of concentration. Meanwhile, the low-temperature environment of quick-freezing cold storage and quick-freezing tunnels operates below the activity temperature of microorganisms and enzymes, effectively inhibiting their growth and biochemical reactions. This better ensures food freshness and improves subsequent cold chain circulation.
Having understood the working principles of quick-freezing and quick-freezing tunnels, how should we choose the right quick-freezing cold storage and quick-freezing tunnel in actual operation?
Quick-freezing cold storage, also known as a quick-freezing warehouse, requires engineers to calculate the refrigeration capacity based on data such as the amount of food to be frozen, the frozen food itself, and the warehouse dimensions, and then select matching refrigeration equipment. The larger the amount of food to be frozen and the shorter the freezing time, the greater the power of the refrigeration equipment required for the quick-freezing cold storage, and the higher the cost of the cold storage. Quick-freezing can be done using ordinary shelves or quick-freezing racks, depending on the packaging method of the products to be frozen and the budget for the cold storage.
Quick-freezing tunnels, also known as tunnel-type quick-freezing machines, can be divided into mesh belt type and plate belt type according to the type of conveyor belt used. Quick-freezing tunnels utilize mesh belts or plate belts for rapid food freezing, resulting in a faster freezing speed compared to cold storage. Furthermore, quick-freezing tunnel systems, such as those using all-aluminum alloy evaporators arranged along the steel plate belt’s running direction, have increased frontal area, reducing frost buildup and enabling continuous, long-term quick-freezing.
Due to the short contact distance between the conveyor belt and the refrigeration equipment, and relying on rapid cooling methods like convection airflow, quick-freezing tunnels are ideal for small-packaged seafood such as shrimp, fish fillets, squid, scallops, and seaweed, as well as frozen pasta products like dumplings and glutinous rice balls.
When using both cold storage and quick-freezing tunnels, the choice depends on the required continuity of freezing. For continuous freezing, a quick-freezing tunnel configuration is recommended. When freezing food in a tunnel, as goods are continuously fed into the tunnel, heat is constantly generated, and the refrigeration unit runs continuously until the goods stop moving, at which point the unit automatically shuts down based on the tunnel’s temperature. This not only improves equipment utilization and production efficiency, but also saves the electricity consumed by the unit due to frequent start-up, thus playing a role in energy conservation.