With evaporative coolers making their way into the fruit and veg preservation sector, a pair of seemingly inconspicuous words suddenly become more consequential. We’re talking about Relative Humidity, about the kind of conditions that could wreak havoc on a freshly harvested barrel of apples or crate full of vegetables. Of much merit here, this type of cooling technology mimics a temperature-regulating effect that’s employed by Mother Nature herself.

Post-Storage Set-ups: Emulating Outdoor Conditions

Vine fruit enjoys a trickle of cooling water while the sun shines. The fruit ripens and is cut from the vine. It’s much the same in a sun-dappled orchard or an open field, with the loamy soil and damp air bringing fruit and vegetable yields to fruition. Technology takes over, the tasty produce is cut and stored, and now a number of evaporative coolers are maintaining a chilly environment. The coolness keeps the harvest fresh. As for the relative humidity in the storage chamber, it’s higher than average, so the shelf life of all of the freshly reaped produce is extended. If the fruit and vegetables were kept too dry, they’d wrinkle and become prune-like. Again, at a low enough temperature and above-average relative humidity, all of that vitamin-rich produce gains a longer shelf life.

Globally Tenable Storage Measures

Some fields of produce are grown around large cities, places that suffer from no shortage of storage resources. If the energy to preserve several fields-worth of strawberries is required in this area, it’s made instantly available. Elsewhere, perhaps in the majority of food growing lands, resources are scarce. High-energy cooling solutions aren’t available out there, so another approach is tendered. Evaporative coolers are installed for these third-world growers. Low on energy consumption, requiring only a refill of recycled water, plus an occasional filter replacement, water-cooled fruit and vegetables provide worldwide nutritional needs and plenty of healthy vitamins. Remember, the goal isn’t to freeze the vegetables or fruit, it’s simply to facilitate a high enough temperature drop, a drop that will maintain a crop’s shelf life until it enters a conventional transport and storage cold chain.

Make no mistake, evaporative coolers are not a technological runner up. They are, in fact, perceived as a more cost-effective and food-friendly food cooling solution. Using that distant food chain example once more, perhaps in Central America or Africa, a drop below a harvest-spoiling 42°C, which isn’t an uncommon temperature in hotter nations, will keep fruit and vegetables preserved until they can be transported and put on sale. In the poorest nations, even an unpowered duct and a wetted pad will help. In more developed nations, a drop of 20°C is possible if that wetted pad is accompanied by powered fans.