Drying of Osmosed Cantaloupe: Effect of Polyols on Drying and Water Mobility

Abstract

Cantaloupe slices were sequentially immersed in 40 and 50 °Brix sucrose solutions for 24 h each. Partial replacement of the 50 °Brix sucrose solution with one of two polyhydric alcohols (sorbitol or glycerol) at 10 or 15% (w/v) was also performed along with a 0% (w/v) polyhydric alcohol treatment and a 10% (v/v) invert sugar partial replacement of the 50 °Brix solution as a control and a reference, respectively. Solids gain (SG) and water loss (WL) were determined up to 48 h later. Conversely, the treatment with 10 and 15% (w/v) sorbitol and the reference showed a significantly higher SG and a lower WL than the control (p < 0.05). The treatments with 10 and 15% (w/v) glycerol presented a significantly lower SG and higher WL than the control (p < 0.05). Increasing concentrations of polyol led to an increase in both the WL and the SG. The osmosed cantaloupe was then dried in a hot air dryer at 60°C, where the numerical drying rate was observed to be as follows: control > 10% sorbitol > 15% sorbitol > 10% glycerol > 15% glycerol > reference, but these differences at each moisture ratio were not significantly different (p > 0.05). Page's model showed a better goodness of fit with the experimental data for all treatments than did the Henderson and Pabis model. The addition of either of the two polyhydric alcohols resulted in a decreased longitudinal relaxation time (T ₁), as monitored using nuclear magnetic resonance (NMR), indicating the decreased mobility of water molecules. Among all treatments evaluated, the sensory analysis derived acceptance scores for the product treated with 10% (w/v) sorbitol were not significantly different from that of the reference (p > 0.05). This may due to the ability of invert sugar and polyols to act as a humectant.

Keywords:

• Cantaloupe
• Glycerol
• NMR
• Osmotic dehydration
• Polyhydric alcohol
• Sorbitol
• Water mobility

ACKNOWLEDGMENTS

This research was supported by funding from the Thailand Research Fund (project no. MRG-WII505S011) and Chulalongkorn University. The authors also thank Dr. Robert Butcher for his English proofreading.

Notes

Different superscript letters in the same column indicate significant difference (p < 0.05).

Different superscript letters in the same column indicate significant difference (p < 0.05).

Different superscript letters in the same row indicate significant difference (p < 0.05).

ns = no significant differences (p > 0.05) in the same row.

Different superscript letters in the same row indicate significant difference (p < 0.05).

ns = no significant differences (p > 0.05) in the same row.