خشك كردن قطعات مكعبي سيب با روش هاي بستر ثابت، نيمه شناور و شناور با هدف توليد چاي سيب

چكيده انگليسي :

68 Drying of Cubic Apple Particles with Fixed Semi Fluidized and Fluidized Bed Methods in Order to Produc Apple Tea Mehdi Zolfaghari m zolfaghary@ag iut ac ir January 14 2014 Department of Agricultural Machinery Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiMorteza Sadeghi sadeghimor@cc iut ac ir Jalil Razavi Jrazavi@cc iut ac ir AbstractApple is an aromatic fruit which has a high nutrient value having antioxidant property vitamin B potassium iodine and iron Consuming of apple is useful for preventing kidney stone and gallstone Drying is one of the most important unit operations in post harvesting technology of agriculture products This process not only increases the shelf life of products but also is of great importance as the first stageof producing a processed product in many cases Due to the high production and existence of differentapple varieties in Iran producing apple tea as a byproduct obtained from dried apple particles is importantfor reducing its post harvest losses In this research cubic apple samples with dimensions of 4 mm and aninitial moisture content of 84 w b were dried using three drying methods including fixed bed semi fluidized bed and fluidized bed at air temperatures of 50 60 and 70 C Because of stickiness andagglomeration of apple particles and hence their fluidization problem in fluidized bed method avibration system with amplitude of 3 mm and frequency of 80 Hz was used for the first 20 minutes ofdrying Drying kinetic color indices hunter L a b water absorption capacity and shrinkage percentagefor three methods were studied and compared Except for the fixed bed method at 60 C in none of thetreatments the constant drying period was observed and the entire drying process was occurred at fallingdrying rate period For modeling the process 9 well known empirical and semi empirical models wereused Based on the results two term model for all fluidized bed treatments and semi fluidized bed ones attemperatures of 60 and 70 C logarithmic model for semi fluidized bed at temperature of 50 C Noomhorn and Verma model for fixed bed method at temperatures 60 and 70 C and modifiedHanderson and Pabis model for fixed bed method at temperature of 50 C described the moisture losskinetics the best The drying method and air temperature had significant effect on drying duration buttheir interaction effect was not significant The fixed bed method at 50 C and the fluidized bed method at70 C had the maximum 120 min and the minimum 65 min drying time respectively Drying methodand its interaction with temperature showed significant influence on shrinkage percentage buttemperature effect was not significant Contrarily the drying method and its interaction with temperaturewere not significant on water absorption capacity of the dried product Whereas air temperaturesignificantly affected this quality attribute The minimum water absorption capacity belonged totemperature of 50 C In terms of the color indices only the L index was changed significantly by thedrying method The samples dried under fluidized and semi fluidized bed conditions at 70 C and thosedried by fixed and fluidized bed methods at 50 C had the minimum and maximum total color differencewith respect to the fresh samples respectively In sensory evaluation tests performed on five drinks madeof the dried samples fluidized bed method at 70 C and oven method at 105 C obtained the first andsecond ranks in terms of taste index respectively From color aspect the drinks made of the oven andfluidized bed dried samples achieved the first and second ranks respectively Keywords Apple color drying rate fluidized bed golden delicious water absorptioncapacity

ذوالفقاري، مهدي

خشك كردن قطعات مكعبي سيب با روش هاي بستر ثابت، نيمه شناور و شناور با هدف توليد چاي سيب

آهنگ خشك شدن , بستر شناور , رنگ سيب , ظرفيت جذب آب , گلدن دليشز