Modelling of high quality pasta drying: mathematical model and validation Massimo Migliori a , Domenico Gabriele a , Bruno de Cindio a, * , Claudio M. Pollini b a Laboratory of Rheology, Department of Chemical Engineering and Materials, University of Calabria, Via P. Bucci Cubo 44/a, I-87030 Arcavacata di Rende (CS), Italy b Pavan S.p.A., via Monte Grappa 8, I-35015 Galliera Veneta (PD), Italy Received 10 November 2003; accepted 13 August 2004 Available online 18 October 2004 Abstract The pasta drying process was studied using an engineering approach. The phenomena of mass and heat exchange between pasta samples and air was modelled according to the classic transport approach applied to a hollow cylindrical shape pasta. Data from the literature and from measurements were used to fix the material parameter values of both the air and dough phases. Theoretical cor- relations were used to obtain a good estimate of mass and heat exchange coefficients between dough samples and air. The proposed model was set by choosing the mass transfer coefficient as the unique optimisation parameter, determined by best fitting of the experimental water content data obtained under given conditions in a static dryer. The model was then validated at different tem- perature and air humidity drying profiles and a good agreement with the experimental results was found. Finally the model was applied to different process conditions and the drying time was calculated from the simulations. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Drying; Food processing; Heat transfer; Mass transfer; Modelling; Pasta production 1. Introduction In the last 10 years, owing to an increased market de- mand for dry pasta in many countries, the requirements of both product quality and production rate have in- creased too. These two aspects are very often considered in contrast each to the other because it is thought that high production rates, characterized by somehow severe process conditions, induce thermal and mechanical damages into the products. These aspects may strongly decrease pasta quality as evidenced by nutrient loss, bad colour, poor texture, marked consistency loss when overcooking, etc. Of course only a careful control of the process conditions coupled to a deep knowledge of the material properties, may avoid those undesired effects, while still maintaining high production rates. Neverthe- less, the production process is currently carried out in a rather empirical way, because it is still based on the practical knowledge of pasta-makers, instead of stand- ing on very well consolidated process engineering basis. In fact, the choice of raw materials and process condi- tions is made by following ‘‘rules of thumb’’ that do not allow any control on the product quality, and they do not match high production rates. Starting from this point, it clearly appears that an engineering approach has to be developed establishing the influence of the main process variables on the final product quality, in order to apply an effective produc- tion control. This objective may be achieved by making a global model capable of simulating what happens 0260-8774/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2004.08.033 * Corresponding author. Tel.: +39 984 496708/496687; fax: +39 984 496655. E-mail addresses: migliori@unical.it (M. Migliori), d.gabriele@ unical.it (D. Gabriele), bruno.decindio@unical.it (B. de Cindio), tecnologie@pavan.com (C.M. Pollini). www.elsevier.com/locate/jfoodeng Journal of Food Engineering 69 (2005) 387–397