At present, the low-temperature logistics cold chain of egg products is developing. For example, the refrigeration method is widely used in the cold chain to store eggs using low temperatures to delay the decomposition of protein in the egg, inhibit the growth and reproduction of organisms, and achieve the preservation of fresh eggs for a long time. The refrigeration method is simple in operation, convenient in management and good in storage effect. Generally, eggs can be kept fresh after being stored for more than half a year. So what will happen to the egg tray that holds the eggs in a low-temperature environment? In the refrigerated food temperature zone below 7 degrees Celsius to above the freezing point, the pulp egg cartons in egg packaging experience an increase in humidity due to condensation that occurs during refrigeration. Condensation refers to the phenomenon of condensation water on the surface when the surface temperature of the object is lower than the dew point temperature of the nearby air. The dew point is the critical temperature point at which the surface of the object begins to condense to form droplets or ice. When the temperature of the surface of the object is equal to or lower than the dew point temperature, condensation will occur on the surface. If the relative temperature drops, the dew point temperature drops accordingly.
When eggs are refrigerated and processed, condensation is prone to occur; refrigerated fresh eggs must be heated when they leave the warehouse, otherwise, due to the excessive temperature difference, a layer of water droplets will condense on the surface of the eggshell, commonly known as “sweating”. This will damage the egg membrane, making it susceptible to microbes and molds, accelerating egg spoilage. The pulp egg cartons that are closely attached to the surface of the eggshell inevitably absorb dew condensation, resulting in changes in structural strength and reduced cushioning performance due to moisture.
For egg packaging in circulation, in order to improve space utilization, pulp egg cartons are often placed in the heavy load state of multi-layer stacking.
state. The decrease in the strength of the pad caused by moisture will lead to a decrease in its buffering effect; the shock and vibration from the transportation process are easy to
Causes damage to multi-layered eggs. This requires that the egg packaging design should face the harsh working conditions of refrigerated egg packaging, and the structure of the buffer pad should be reasonably designed to achieve reliable packaging protection within a certain humidity range.
The technological progress of cold chain logistics of agricultural products also brings the potential failure risk of traditional pulp egg cartons in a refrigerated environment. Here are some conclusions:
(1) Compared with cardboard materials, pulp molded products are more sensitive to humidity changes due to the buffer mechanism and are more susceptible to moisture.
(2) During the cold chain logistics process, the pulp egg cartons in the low-temperature environment have a tendency and possibility of increasing humidity.
(3) In the process of cold chain logistics, due to the increase of material humidity, the cushioning performance and bearing strength of pulp egg cartons will be different.