بررسي پارامترهاي موثر بر توليد بيوپليمر زانتان در محيط كشت شيره انگور و خرما

چكيده انگليسي :

Study of Effective Parameters in Production of Xanthan Biopolymer in Grape and Date Extracts Sahar Nejati Sahar nejati@yahoo com 26 6 2011 Departmant of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiS M Ghoreishi ghoreshi@cc iut ac irH Zilouei hzilouei@cc iut ac irAbstract Xanthan gum is a natural bio polymer produced from growth of Xanthomonas campestris bacteria Specialoutstanding properties of xanthane have made it so much useful in various industries including food medicine andhygienic oil ceramics printing etc and the annual consumption throughout the world is ever increasing as a result it is tried to reduce production costs for the better xanthan gum production rates by means of available cheapersubstrates as well as the application of different operation methods The aim in this work was to examine thepossibility of xanthan production from grape extract sugar source for the first time and relevant production volumefrom other carbon sources such as date extract and compare its results with that For this purpose three influentialparameters namely carbon grape extract and date extract phosphorus K2HPO4 and nitrogen NH4NO3 wereconsidered within the respective ranges of 30 150 4 12 and 3 9 g L designed of experiments was performed usingcentral composite design method in three levels and twice repetition in an absolute random way under constanttemperature 28 C and 72 hours fermentation In this project dry weight method was applied to measure thecellular mass and yielded product The influence of different parameters on production rate was examined andxanthan gum production and cellular mass model was gained for both carbon sources i e grape extract and dateextract Optimum levels and the amount of produced xanthan were determined by the software in these levels Afterthat experimental tests were taken in these levels The largest amounts of theoretical and experimental production ofxanthan from grape extract sugar source at 86 97 g L carbon source 8 2 g L phosphorus source and 3 g L nitrogensource were respectively equal to 10 30 and 10 16 g L and the same for date extract sugar source in levels of 77 3g L carbon source 12 g L phosphorus source and 3 g L nitrogen source were respectively equal to 13 27 and 12 74g L Taking into account the fact that this process is divided into two phases i e microbial growth at the first 24hours of fermentation process fllowed by production in the second phase Optimum temperature as well as optimumcarbon source are different in these two phases therefore another experiment was designed in order to evaluate theeffect of variation during microbial growth and xanthan product During the first 24 hours of fermentation experiments were started at 28 C and 30g L concentration of carbon source and optimum levels of phosphorus andnitrogen sources while temperature of production phase was increased to 32 C and 30 g L carbon source was addedto the fermentation Erlenmeyer under sterile conditions the result of these tests for both grape and date extractssugar sources respectively 16 7 and 15 6 increase were gained in the production rate in comparison with the testsunder constant temperature without feeding in optimum levels Keywords Xanthan bio polymer grape extract date extract CCD feeding temperaturechanges

نجاتي، سحر

بررسي پارامترهاي موثر بر توليد بيوپليمر زانتان در محيط كشت شيره انگور و خرما

‍ِ‍‍CCD , خوراك دهي , تغيير دما