Mass transfer during osmotic dehydration and its effect on anthocyanin retention of microwave vacuum-dried blackberries.

Background: The combination of sugar osmotic dehydration and microwave vacuum drying is an effective method for the dehydration of blackberries, the retention of their antioxidant properties, and the extension of their shelf life. Mass transfer during the osmotic dehydration of blackberries in sugar solution was investigated together with its influence on microwave vacuum drying characteristics, and the retention rate of anthocyanins in dried frozen blackberries.

Results: The concentrations of the osmotic solutions that were tested contained 40%, 50%, and 60% sugar, and the osmotic solution temperatures were 30 °C, 40 °C, and 50 °C.

Visualization of microwave energy distribution in a multimode microwave cavity using CoCl2 on gypsum plates.

This study provides a facile method to map the microwave field distribution in a multimode microwave cavity. Anhydrous calcium sulfate powder was used to make the gypsum plates that were used as the carrying medium. Cobalt chloride hexahydrate, whose color changes when losing part or all of its crystal waters, was selected as an indicator of the energy absorption.