J. A. Carcel Universitat Politecnica de Valencia

De (m^2/s)	Weq (kg w/kg d.m.)
VAR (%)
Drying	HAD AFD	7.64D0'^10 5.15-10’^11	- -	89.30 90.37
Rehydration	HAD AFD	4.4340'^9 2.5640'^8	6.496 9.653	96.56 88.58

Texture
Hardness was determined from force/deformation profiles obtained by texture profile analysis of the rehydrated samples. The average values of the hardness for the rehydrated eggplant cubes are plotted in Figure 3. The value for the fresh cubes (9.9±4.7 N) is not plotted because its magnitude was one order of magnitude higher than dried samples. Dehydration involves a high degradation of eggplant structure [9], thus rehydrated samples don’t recover the initial texture. Regardless the drying method, dried/rehydrated samples were much softer than fresh eggplant. Significant differences (p<0.05) between the texture of dried samples were also observed. VFD samples showed the lowest and HAD the highest hardness after rehydration. AFD samples showed intermediate textural properties.





Figure 3. Hardness of rehydrated eggplant cubes: atmospheric freeze dried (AFD), vacuum freeze dried (VFD) and hot
air dried (HAD). Average values and LSD intervals.


CONCLUSION
Drying method prompted changes in textural properties, as well as, rehydration pattern of eggplant samples. AFD samples showed an intermediate rehydration rate and hardness between HAD and VFD samples. Therefore, AFD could represent an interesting alternative to HAD and VFD to achieve high quality dried products with lower cost than VFD. Its application at industrial scale needs a thorough study on the influence of different variables in both, the kinetics of drying process and the final quality of the dried product.


ACKNOWLEDGEMENTS
The authors acknowledge the financial support of the Ministerio de Ciencia e Innovation (MICINN) of Spain from the project DPI2009-14549-C04-04.
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[9] Garda-Perez J.V., Puig A., Perez-Munuera I., Carcel J.A. & Riera E. 2010. Kinetic and microstructural changes induced by power ultrasound application on convective drying of eggplant. Proceedings of 20^th International Congress on Acoustics, ICA 2010, 23-27.

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