Influence of humectants on the drying kinetics, water mobility, and moisture sorption isotherm of osmosed air-dried papaya

ABSTRACT

Papaya slices were sequentially soaked in 40, 50, and 60° Brix sucrose solutions. There was a higher water loss and solids gain when 60° Brix sucrose solution was partially substituted with 10% (w/v) sorbitol, 10% (v/v) glycerol, or invert sugar. The modified Henderson and Pabis model provided the best fit to experimental drying kinetics. Moisture sorption isotherm of all dried papaya, at 30 ± 2°C, was a type III with different curvature, revealing different sugar-binding ability towards water molecules. The Henderson model showed suitable fit to experimental desorption isotherm data. NMR water mobility revealed the better ability of glycerol to bind water than sucrose.

KEYWORDS:

• Dried fruit
• glycerol
• moisture sorption isotherm
• osmotic dehydration
• papaya
• sorbitol

Acknowledgments

The authors thank Dr. Chaleeda Borompichaichartkul for comments on MSI and Dr. Robert Butcher for his English proofreading.