Can cold stores be warmed up?

Can cold store operators raise the temperature in their cold stores was the question posed by Judith Evans at the 13th Cold Chain Logistics conference in Amsterdam recently.  Raising the temperature of cold stores is an interesting idea that has been debated for some time.  Raising the evaporating temperature by 1°C should in theory reduce energy consumption by 2-3% and so this is not an insignificant saving, especially if temperature could be raised by several degrees. In the UK cold stores are often maintained at -22/-23°C and this is for a variety of reasons that were outlined in Judith’s presentation. It is therefore not always simple or possible to raise evaporating temperatures due to logistical or contractual issues.  Often operators are constrained by contracts that define operating temperatures and so cannot easily change these.  Stores are also often operated to take advantage of cheaper off peak energy prices and operators allow temperatures in the store to rise during periods of high tariffs.  Although this may be good for the ‘bottom line’ evaporating temperatures are lower than necessary during operation of the refrigeration plant.  A number of other factors also can prevent operators raising evaporating temperature and many of these can be overcome by maintenance or alternative operational practices.

Raising the storage temperature of chilled food it is unlikely to generate substantial savings as food safety must not be compromised.  However, some frozen food could potentially be stored at a higher temperature. The storage lives of products such as meat are greatly affected by what happens to the food prior to freezing and this can have a far greater effect than storage temperature.  On the other hand product such as ice cream are especially sensitive to storage temperature and higher temperature or temperature fluctuations can cause ice crystals to agglomerate and results in poor quality product.  Therefore if products are mixed in cold stores there is a need for low stable temperatures for one product whereas another can tolerate higher temperatures.  This then leads to the potential need for more than one cold chain and the associated logistic operations.  Although this may well be possible it adds complexity to the already complex food cold chain.

If you would like further information on raising temperatures in cold storage please contact Judith at RD&T: j.a.evans@rdandt.co.uk

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