Determination of porosity change from shrinkage curves during drying of food material

J. Madiouli (1) , J. Sghaier (1) , Didier Lecomte (2) , H. Sammouda (1)

1 LETTM - Laboratoire d’Énergétique et des Transferts Thermiques et Massiques [Tunis]
2 RAPSODEE - Centre de recherche d'Albi en génie des procédés des solides divisés, de l'énergie et de l'environnement

Based on a very simple model of mass conservation, three experimental properties (solid density, liquid density and initial bulk density) and the simultaneous acquisition of the reduced moisture content and the volume shrinkage during drying, a simple method is proposed to calculate the bulk porosity of a material during drying. This model allows a graphical interpretation to visualize the porosity change by comparing the experimental shrinkage curve with an ideal shrinkage curve. In the present work, several examples were taken from the literature to illustrate the application of this method to foodstuffs (apple, banana, carrot, garlic, pear, potato and sweet potato) with two different processes (convective drying, freeze-drying) and different drying conditions. Porosity calculations including error estimations showed a good agreement with experimental values reported in the literature.

Mots clés: Porosity; Model; Foodstuffs; Shrinkage; Collapse

Domaines: Sciences de l'ingénieur [physics]

J. Madiouli, J. Sghaier, Didier Lecomte, H. Sammouda. Determination of porosity change from shrinkage curves during drying of food material. Food and Bioproducts Processing, 2012, 90 (C1), pp.43-51. ⟨10.1016/j.fbp.2010.12.002⟩. ⟨hal-01688419⟩