Effects of Osmotic Treatment and Superheated Steam Puffing Temperature on Drying Characteristics and Texture Properties of Banana Slices

Abstract

A porous structure is an important characteristic of crisp food and can be produced by a puffing process. However, puffed products may brown during puffing. To limit the browning reaction, food, in particular fruits, needs to be osmotically treated before puffing. This research therefore studied how osmotic treatment affects the quality of a puffed fruit sample, viz. banana. Banana with 20–23° Brix total soluble solid was immersed in sucrose solution concentrations at 30, 35, and 40° Brix and dried at 90°C using hot air until the sample moisture content was reduced to 30% dry basis. Then the banana slices were puffed using superheated steam at 180, 200, and 220°C for 150 s and dried again at 90°C until the sample moisture content reached 4% (db). It was found that osmotic dehydration could improve the color of puffed banana, with less browning than the non-osmotically treated puffed banana because the amounts of glucose and fructose in banana, which serve as important reagents for browning reactions, were decreased. The puffing temperature and osmotic concentrations did not enhance the browning rate. Sucrose impregnation resulted in longer drying times and limited banana cell wall expansion due to the interaction between the hydroxyl group of sucrose and that of banana tissue. This interaction further resulted in significantly higher shrinkage of the osmotically treated sample and a denser structure as viewed by scanning electron microscopy. The morphology of osmotically treated banana was a hard and brittle texture.

Keywords:

• Color
• Drying
• Osmotic dehydration
• Puffing
• Texture

ACKNOWLEDGMENTS

The authors express their sincere thanks to the Thailand Research Fund, National Science and Technology Development Agency, and King Mongkut's University of Technology Thonburi for financially supporting this project. S. Tabtiang thanks the Commission on Higher Education, Thailand, for supporting the grant fund under the Strategic Scholarships for Frontier Research Network of the Ph.D. program Thai doctoral degree.

Notes

Different superscripts in the same column indicate a significant difference at p ≤ 0.05.