مدلسازي انتقال جرم و حرارت نان سنگك نيم پخته بسته بندي شده تحت اتمسفر اصلاح شده

چكيده انگليسي :

Heat and Mass Transfer Modeling of Part Baked Sangak Bread Packaged in Modified Atmosphere Khadije khoshakhlagh k khoshakhlagh@ag iut ac ir January 31 2012 Department of Food Science and Technology Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiNasser Hamdami hamdami@cc iut ac irMohammad shahedi shahedim@cc iut ac irAbstractAs the result of the increase of the level of the consumers s awareness recent years have witness theemphasis which the food experts and researchers have placed on producing minimal processing andsustainable high quality products as their main objectives Modified atmosphere packaging isconsidered to be one of the most effective and applicatory food technology outcomes in response tothis need of consumers The foundation of this method is the replacement of the closed air with anappropriate gas composition to increase the shelf life of the product Currently about 30 percent of wheat production in the country is wasted in the chain of wheat flourand bread Since the inappropriate conditions of bread production and its maintenance is one of themost important reasons for the amount of waste prolong the shelf life of Sangak bread as one of thebest bread in the world in terms of nutritional value and flavor and aroma characteristics wasconsidered in this study So that baked off technology as an effective way of staling and modifiedatmosphere packaging to increase shelf life was used For this part baked Sangak bread waspackaged with three combinations gas included 100 CO2 50 CO2 50 N2 25 CO2 75 N2and air as a control and storage at 25 C for 21 days During storage quality and microbial features ofproduct such as color volume moisture texture total count and mold and yeast count was assessed atintervals of three days On the other hand the gas composition in the packages is changing duringstorage due to the dynamic nature of microbial and chemical of food and changes caused bypermeability of packaging film gas solubility in food moisture evaporation etc So In order tooptimize packaging conditions to achieve maximum shelf life of the product modified atmospherepackaging systems modeling seems necessary Hence heat and mass transfer phenomena in order topredict the profiles of temperature and gas composition was studied In this regard a one dimensionalmathematical model was developed to describe simultaneous heat and mass transfer in part bakedSangak bread packaged in modified atmosphere packaging during storage Statistical analysis of the results of part baked Sangak bread quality characteristics during storageshowed that carbon dioxide in headspace of package No significant effect was on product color texture volume and moisture while the microbial load of the samples were thoroughly impressed bythe atmosphere of the package So that with increasing concentrations of carbon dioxide the growthof total microorganisms mold and yeasts was more limited Also was observed all product qualitycharacteristics changes significantly during storage time So that the reduced moisture increasedcrumb firmness reduced crust firmness reducing the volume increased L and a values and reducedb value color of part baked Sangak bread was observed during 21 days Finally the high correlationbetween the temperature profiles gas and relative humidity predicted and measured indicated thatdeveloped model is able to predict changes temperature in different points of part baked bread surface of package head space gas composition in package and concentration of each gas in productduring storage at different temperatures Keywords Modified atmosphere packaging part baked Sangak bread Mass transfer Heat transfer Mathematical modeling Thermophysical properties quality characteristics Microbial growth

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مدلسازي انتقال جرم و حرارت نان سنگك نيم پخته بسته بندي شده تحت اتمسفر اصلاح شده

بسته بندي اتمسفر اصلاح شده , انتقال حرارت , مدل سازي رياضي , خواص ترموفيزيكي , رشد ميكروبي