Table of Contents
Journal of Food Processing
Volume 2014, Article ID 524705, 10 pages
Research Article

Thermal, Structural, and Physical Properties of Freeze Dried Tropical Fruit Powder

1Department of Food Process Engineering, Faculty of Engineering and Technology, SRM University, Kattankulathur, Tamil Nadu 603203, India
2Department of Physics, Government Arts College, Nandanam, Chennai, Tamil Nadu 600035, India
3Valliammai Engineering College, Kattankulathur, Tamil Nadu 603203, India

Received 1 August 2014; Revised 19 October 2014; Accepted 19 October 2014; Published 22 December 2014

Academic Editor: Raquel P. Guiné

Copyright © 2014 K. A. Athmaselvi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study evaluates the physical properties of freeze dried tropical (guava, sapota, and papaya) fruit powders. Thermal stability and weight loss were evaluated using TGA-DSC and IR, which showed pectin as the main solid constituent. LCR meter measured electrical conductivity, dielectric constant, and dielectric loss factor. Functional groups assessed by FTIR showed presence of chlorides, and O–H and N–H bonds in guava, chloride and C–H bond in papaya, and chlorides, and C=O and C–H bonds in sapota. Particle size and type of starch were evaluated by X-ray diffraction and microstructure through scanning electronic microscopy. A semicrystalline profile and average particle size of the fruit powders were evidenced by X-ray diffraction and lamellar/spherical morphologies by SEM. Presence of A-type starch was observed in all three fruits. Dependence of electric and dielectric properties on frequency and temperature was observed.