Food begins to deteriorate and/or spoil from the time that it is harvested or slaughtered. The process accelerates as the cells begin to break down and deterioration sets in. The spoilage process is exacerbated when the food is externally contaminated with bacteria (pathogenic and non-pathogenic), moulds and yeasts. The food will develop off flavours, odours and a breakdown in texture, and before long it will no longer be fit for human consumption.

To counter the foregoing potential food spoilage/poisoning threat, professionals working in large commercial and industrial food production/storage environments tend to concentrate on ambient and core temperatures in their cold chain as their only standard/measure that they are storing a food product safely and not at a loss. Many food safety audits and auditing practises are based on the self-same same philosophy; swabbing away; with temperature measuring devices  prodding and probing; but no hygrometer to measure relative humidity?

Whilst low ambient and core temperatures are undoubtedly necessary to prevent food spoilage, the consequent colder air dries out the internal atmosphere of the storage facility and the stored refrigerated food stock begins to lose condition, weight and firmness as a result of moisture exiting the produce to counter balance the drier air. The lower the temperature, the drier the air, the higher the loss of condition of the stored food stocks.

The importance of storing food produce at the correct humidity cannot be overemphasised and “one size, fits all” is a recipe for disaster – both in terms of shortened qualitative shelf-life as well as bottom line! By way of example, fresh fruits and vegetables contain between 90% and 95% water and should the internal humidity in the cold chain drop to below that humidity level the produce will have to give up moisture resulting in shrinkage, loss of firmness and weight.

Food manufacturing and food audit/safety professionals are well advised to ensure the contents of  their cold chain are not only monitored from an ambient/core temperature perspective only but as importantly from the correct humidity level perspective and each type of produce as a differing humidity requirement. I have yet to see a food safety audit sheet that lists humidity as an item to be monitored and measured!

Whether commercial and industrial cooling systems can consistently deliver high levels of humidity of 90 to 95% (when required) – which they cannot – is the subject of another discourse to follow.