Is Your Freezer Saving or Ruining Your Frozen Inventory?
No one likes eating soggy vegetables, or fruit that has lost its crunch, or – worse yet – ice cream that feels sandy and coarse in your mouth. Foods, from fruits and vegetables to meat to grains, are primarily made up of water, about 70 to 90 percent of the food’s content. Freezing food creates ice crystals and the number of crystals, their size and their shape can all affect the texture, flavor, and quality of our food.
Fluctuations in temperature, including fluctuations below freezing, impact these factors the most. While the difference between 14°F and 23°F (-10°C and -5°C) is unimportant for pure water, the water in our food contains components with low molecular weight, such as sugars and minerals, which lower its freezing point. As a result, even at -1°F (-18°C) some of that water will remain unfrozen! When the temperature increases some of the ice crystals will melt. As the temperature decreases, larger ice crystals will form, damaging the cellular structure and decreasing the quality of the food. Therefore, a fluctuation between 14°F and 23°F (-10°C and -5°C) might make the difference between crisp and crunchy vegetables, and a soggy mess.
“The cell structure in many foods is quite small, so to maintain food texture the ice crystals that form during freezing should be small as well,” states Dr. Dennis R. Heldman a professor of Food Engineering at The Ohio State University. “This can be achieved by freezing food as rapidly as possible, like with the individually quick frozen method, which uses liquid nitrogen to freeze small pieces of foods in minutes (actually seconds). In a storage setting, however, food cannot be frozen that rapidly. That’s when large ice crystals are formed and disrupt the cell structure and result in changes in texture.”
While food texture is most impacted by temperature fluctuations, aroma and taste can also be impacted. The freezers in a grocery store are especially prone to temperature fluctuations that are difficult to control due to constant traffic in and out of the freezer, new product being added, and doors being propped open.
“We have found that a 9°F (5°C) change in temperature can potentially shorten the shelf life of a product by a couple of months,” continues Dr. Heldman. “Customers are also more likely to throw out food that has lost its texture, resulting in food wastage.” This has a negative effect on the brand perception of both the retailer and the manufacturer.
The key to maintaining the quality of frozen food is maintaining stable freezer temperatures. Since it can be challenging to control heat infiltration in grocery store cold storage areas, you need a system that can buffer against temperature fluctuations. Viking Cold Solutions’ thermal energy storage (TES) system uses its proprietary phase change material (PCM) to act as a heat buffer to reduce temperature fluctuations and crystallization in food. During off-peak hours – when energy pricing is at its lowest – the existing refrigeration equipment freezes the non-toxic, environmentally-safe PCM. During on-peak hours – when demand-based pricing is at its highest – the refrigeration system can be cycled off for long periods of time as the PCM begins its phase change. During this transition the PCM absorbs 300 times more thermal energy than the food, and can absorb 85 percent of all heat infiltration in the freezer while using less energy.
It is challenging and expensive to maintain stable temperatures in high traffic cold storage areas with only a refrigeration system. Viking Cold Solutions’ TES systems help reduce temperature fluctuations by absorbing heat entering your freezers keeping your vegetables crisp, your ice cream smooth, and your energy expenses low.
