An innovative system dehydrates fruit without heat

Dry fruits are a delicious snack or a sweet addition to the recipes, but the water elimination process often requires heat and energy. In a step towards a more sustainable food preservation, researchers report ACS Science and Food Technology have developed a method of drying food at room temperature by adjusting air pressure conditions and using calcium chloride secured by food.

In proof of concept, the system has managed to dry the mango and apple slices at commercial levels.

Food dehydration transforms perishable articles such as fruits into long-term pantry staples. Most food dehydrators on the table and on an industrial scale use hot air circulated to eliminate humidity, which is simple and effective but requires a lot of energy. Foods attracting the sun mainly use solar energy but are slow and darken the final products.

The researcher Luis Bastarrachea develops food preservation processes that do not require heat. In this most recent study, the chloride of salt calcium adsorbling humidity, an ingredient used in cheese gastronomy and molecular applications, was incorporated into a method of dehydration at room temperature and tested to see if it would have an impact on the color of the drying fruit.

The researchers built a dehydrating room without heating with three screen sets above a container of calcium chloride solution. They placed mango and apple slices on the screens, then compared two drying methods at room temperature: one with the room at the standard air pressure and the other under a slight emptiness.

After four days under standard air pressure, calcium chloride solutions fired and ads less humidity from the fruit than those placed under vacuum. Standard air pressure slices have also dried inconsistently. The slices on the upper screen contained 50 to 70% of water (in weight) and those at the bottom had 20 to 30% of water after the dehydration process.

On the other hand, the vacuum assisted method produced parts of mango and apple dried regularly composed of around 30% humidity, which is similar to the quantity in the commercial fruits available commercially, and has represented an elimination of approximately 95% of the initial water mass.

The pieces of dried mango under vacuum kept the pretty bright yellow color of the raw fruit; However, the two methods of dehydration darkened the apples by similar quantities. In addition, scanning electron microscopy images have shown the degradation of starch granules in all samples, but more of them broke down under standard pressure, which suggests that the vacuum assisted method slows down the deterioration mechanisms and keeps freshness.

The water withdrawn from the fruit could potentially be reused. Bastarrachea says that “the water collected in the calcium chloride solution can be eliminated by evaporation, and the self -granted calcium chloride solution can be reused in more dehydration cycles”.

In the end, recovered water could be used in industrial applications or treated more for human consumption.