The Theory Of Moisture Migration Of Multi-component Foods In Packaging Systems And Its Applications

The application range of composite food is increasing widely, carrying out its moisturediffusion research is very important for ensure its quality and predicting its shelf life.Moisture transport in food between components and the exchange of water inside and outsidethe package are interrelated and performed at the same time. Consider packaging headspace,packaging headspace will share part of the moisture that penetration through the package.Using the biscuit, the agar gel and the haw jelly as the subject, study was carried out basingon Fick’s law as follow:1. Using the conventional method of equilibrium with saturated salt solutions to carry outthe moisture sorption isotherm experiments of the biscuit, the agar gel and the haw jelly. Andmoisture sorption isotherm model was obtained by minimizing the sum of the squares of theresiduals using Levenberg–Marquart. The result showed that Ferro-Fontan model was thebest fit model for biscuits and agar gel adaptability compared to other models.2. Dynamic water vapour adsorption experiment was conducted for subjects, andeffective diffusion coefficient values were calculated by Crank equation at20℃. Effectivediffusion coefficient as a function of moisture content was described by empirical model.3. In impermeable package condition, the study solved the Fick’s second law to obtainthe numerical solution of moisture content variation of time of two-component foods in bothimperfect and perfect contact conditions when considering air resistance. The numericalsolution under different contact area conditions was derived basing on those conditions. Andcarried experiments using the biscuit and the agar gel to verify those solutions, the resultsshow that experimental data could fit the theoretical model very well.4. In impermeable package condition, changed arrangement of components inmulti-component foods, and established the moisture diffusion model of the multi-componentfood arranged as high-intermediate-low, intermediate-low-high and intermediate-high-low. And carried experiments using the biscuit, the agar gel and the haw jelly to verify thosesolutions, the results show that experimental data could fit the theoretical model very well.5. In permeable package condition, moisture diffusion model of two-component foodswas established basing on Fick’s law combined with the permeable package theory, and thennumerical solutions of moisture diffusion of one component in permeable package conditionwas solved and use biscuits to verify. This theory was applied to two-component foods, andmodified the model considering the package headspace, and then get the moisture diffusionmodel of two-component foods with package headspace in permeable package condition, andwas verified by biscuits with agar gel, the results show that the theoretical model has goodpredictive performance.6. Shelf life prediction of proof packaging system was designed based on Matlab GUI,which have a comprehensive and easy to operate interface. This system can determinemoisture sorption isotherm model of components moisture, predicted shelf life for ofone-component, two-component and multi-component foods, and optimize the choice ofpackage according to the system.