Researchers test no-heat vacuum method to dehydrate fruit

Researchers have developed a room-temperature fruit dehydration process that uses a vacuum and calcium chloride to remove moisture without applying heat. The system produced dried mango and apple slices with moisture levels similar to commercial products.

A team led by Luis Bastarrachea tested the method as an alternative to conventional hot-air dehydration, which requires significant energy, and to sun drying, which can discolor products. The researchers built a chamber with three stacked screens placed above a container of calcium chloride solution.

Mango and apple slices were dehydrated under two conditions: standard air pressure and slight vacuum. After four days, the vacuum-assisted method removed about 95% of the initial water mass, resulting in fruit with approximately 30% moisture. Drying under standard pressure produced uneven results, with slices on the top screen retaining up to 70% water while those on the bottom contained as little as 20%.

Vacuum-dried mango retained a bright yellow color, while apples darkened similarly under both conditions. Microscopy images showed breakdown of starch granules in all samples, but more deterioration occurred at standard pressure.

The researchers note that water collected in the calcium chloride solution could be recovered by evaporation and reused for further dehydration cycles or industrial applications.

The study is published in ACS Food Science and Technology.