Effect of Osmotic Treatment on Drying Kinetics and Antioxidant Properties of Dried Mulberry

Abstract

Air drying is widely used in fruit preservation. However, this causes a reduction in the nutritive value of the product. Osmotic treatment has been used as prior to drying. The objectives of this research were to study osmotic treatment in combination with air drying of mulberries and to evaluate the influence of different osmotic solutions on drying kinetics, reaction kinetics, and antioxidant capacity, with a focus on anthocyanins and phenolics. Mulberries, either untreated or osmotically treated with sucrose, sorbitol, and maltose, were dried in a tray dryer at 60°C with a velocity of 1 m/s. The drying kinetics of mulberries were explained using the Page model based on the R ² values, which ranged from 0.985 to 0.993, and E _s , which ranged from 0.031 to 0.091. Air drying caused degradation of anthoyanins and phenolics, which followed a zero-order reaction with R ² values ranged from 0.866 to 0.996. Osmotic treatment with maltose was found to be a good treatment for mulberry drying and preserved the phenolic and anthocyanin contents and provide high antioxidant capacity.

Keywords:

• Anthocyanins
• Antioxidant
• Degradation
• Drying
• Kinetics
• Mulberry
• Osmotic
• Phenolics

ACKNOWLEDGMENTS

The authors thank the Thai Research Fund (TRF) of Thailand for financial support. The first author would also like to express greatest appreciation to Professor Dr. Somchart Soponronnarit for his kindness and valuable advice.

Notes

^a Different letters in the same row indicate statistical difference at p < 0.05.