Food Preservation Using Refrigeration and Air Conditioning Systems
Can you guess the one thing that refrigerators have in common with air conditioning units ? Well, besides cooling, they also dehumidify, and these are the two most important working principles of both appliances. One the one hand, successful food preservation requires you store the food in a cool and dry place, and on the other hand, a cool and dry bedroom is all it takes to enjoy pleasant sleep on a warm summer night. For these reasons refrigeration and room air conditioning appliances are generally treated as a single subject, but of course, both appliances do have other applications and involve other processes besides cooling and dehumidification.
Did you know that microorganisms which cause food deterioration grow much faster at temperatures of 10°C than they do at 4°C? When it comes to food preservation, the slightest temperature difference can make a huge difference in determining how long the food stays fresh. Cool temperatures slow down the bacterial action so that food takes much longer to go bad. Instead of spoiling after two days, the food could end up spoiling after even two weeks thanks to the slow-moving bacteria.
Freezing, on the other hand, employs extremely cool temperatures – even sub-zero –, and in these cases, the bacteria is rendered completely inactive. For this reason, freezing is a more long-term method of food preservation.
Bacteria grow when there is excess humidity present, but this is not the only detrimental effect on food preservation. In the presence of excess humidity, condensation would form on cold products and this could in turn damage the packaging thus compromising the quality of the product. Food preservation, therefore, requires maintenance of the desired humidity level, hence why refrigeration and air conditioning systems (RAC) incorporate dehumidification besides just the cooling process.
However, humidity in the atmosphere is highly dependent on the ambient temperatures. Warmer air is capable of holding more moisture, and the reverse is also true. RAC systems, therefore, regulate these two interdependent factors to create ambient conditions for food preservation.
We cannot quite cover the importance of dehumidification in RAC systems, without discussing the factors that cause moisture build-up in a refrigerator in the first place. There are factors that will disrupt the ambient conditions within a refrigerator, by introducing warm, humid air into the fridge. These include:
a) Power outages or constantly powering the fridge off might temporarily result in moisture build up.
b) Frequent opening of the refrigerator doors especially when the weather is particularly hot and humid.
c) Not closing the refrigerator doors completely due to a blocked door closure or improper leveling of the unit.
d) Defrost cycles generate some warm air in the fridge, and when this air comes into contact with the colder interior temperatures, moisture could form on surfaces such as the shelves and the side walls.
e) Refrigerating food and beverages in open containers could result in the moisture within the food being transferred to the interior air.
f) Moisture-laden vegetables such as celery should be wrapped appropriately and stored in the correct refrigerator compartment. Failure to do this could again, result in transference of that moisture to the air inside the fridge.
g) Having incorrect humidity and temperature control settings could result in frozen vegetables and moisture build-up inside of the vegetable bin.