Heat and mass transfer modeling during storage of part-baked Sangak traditional flat bread in MAP Khadije Khoshakhlagh a , Nasser Hamdami a,b,⇑ , Mohammad Shahedi a,b , Alain Le-bail c,d a Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran b Center of Excellence in Food Safety and Quality, Isfahan University of Technology, Isfahan 84156-83111, Iran c LUNAM University, Oniris, UMR 6144 GEPEA, BP 82225, 44322 Nantes Cedex 3, France d CNRS, Nantes F-44307, France article info Article history: Received 18 June 2013 Received in revised form 27 April 2014 Accepted 29 April 2014 Available online 9 May 2014 Keywords: Modified atmospheres packaging Mathematical model Heat and mass transfer Part-baked Sangak bread abstract Modified atmosphere packaging (MAP) induces some interaction between product and ambiance; the interaction is linked in particular to heat and mass transfer phenomena during storage time. In order to study changes in a MAP system, heat conduction and convection, gas solution and diffusion, gas per- meation in the polymeric film, evaporation and condensation phenomena have been accommodated in a mechanistic model. The model has been validated against experimental data of part-baked Sangak bread packaged in 100% CO 2 . The good match between predicted and experimental data confirmed validation of the model. Results showed that the storage temperature has an important impact on the headspace gas composition and volume of package. In this study, because of the important effect of CO 2 solubility on equilibrium gas composition, CO 2 solubility for part-baked Sangak bread was measured experimentally. The developed model is a suitable tool for describing and optimizing the MAP of non-respiring products in flexible plastic packages. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, there has been increasing demand for mini- mally processed and near-fresh quality products. Bake-Off Tech- nology (BOT) not only reduces economic losses due to staling, but also provides the possibility of fresh bread for consumers at any time (Lainez et al., 2008). However, the shelf life of part-baked products is very short and it is a problem to maintain their quality during prolonged storage (Karaoglu et al., 2005). Modified atmo- sphere packaging (MAP), consists in packaging of a perishable product under a different gas composition than air, which can increase product shelf life while maintaining its quality (Rodriguez-Aguilera and Oliveira, 2009). The most used gas for MAP is carbon dioxide (CO 2 ), because it is a non-toxic gas with well known anti-microbial effects (Simpson et al., 2009). Nitrogen (N 2 ) is also used in MAP in combination with carbon dioxide. N 2 is an inert and tasteless gas; however, it is not identified as a gas having specific anti-microbial activity and is mainly used for replacement of oxygen and to prevent package collapse (Rodriguez-Aguilera and Oliveira, 2009). Maintaining an optimum internal atmosphere in package is the main factor in quality preservation of products in MAP (Lee et al., 2000). Mathematical modeling of MAP systems is a suitable tool for understanding and describing the transfer phenomena between food, head space and ambient atmosphere. So it can predict behav- ior of these phenomena under hypothetical conditions. Therefore, using mathematical models, system optimization to achieve max- imum quality and shelf life will be possible without costly and time-consuming experiments. Generally, gas exchange in MAP sys- tems depends on internal factors such as type of product, packag- ing material permeability, microbial load and product ingredients and external factors such as temperature and storage time (Lioutas, 1988). Existing mathematical models on the MAP are divided into two categories based on product type: respiring and non-respiring products. So far,several models have been proposed to apply in respiring products (Talasila et al., 1995; Fonseca et al., 2002; Gonzalez et al., 2008; Rodriguez-Aguilera et al., 2009). The main mechanisms of gas exchange in these cases are the product respiration and gas transfer through the packaging material (Simpson et al., 2001; Rodriguez-Aguilera and Oliveira, 2009). It appears that few modeling studies in non-respiring products are http://dx.doi.org/10.1016/j.jfoodeng.2014.04.019 0260-8774/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran. Tel.: +98 311 3913428. E-mail address: hamdami@cc.iut.ac.ir (N. Hamdami). Journal of Food Engineering 140 (2014) 52–59 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng