ࡱ> EHFOh+'0 $0 L X dpx)Optimisation of inulinase production by ordptiProf. Z. KurtanjeklrofNormal.Prof. Z. Kurtanjekl5ofMicrosoft Word 8.0l@[@2@kC4fice0Templatest!@A_L՜.+,D՜.+,d  hp  PBF U. of Zagrebsj )Optimisation of inulinase production by Title(RZ _PID_GUID _PID_HLINKSAN{A0B832BF-4D7D-4716-851A-04EEOptimisation of inulinase production by Kluyveromyces bulgaricus Darija Vraneai1, }elimir Kurtanjek1* and Francisco Maugeri Filho2 1Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia 2Department of Food Engineering, Universidade Estadual de Campinas, SP, CP 6121, Cep 13081-970, Brazil Summary Present work is based on observation of an effect of pH and temperature of fermentation on the production of microbial enzyme inulinase by Kluyveromyces bulgaricus (former Kluyveromyces marxianus). Inulinase hydrolyses inulin, an oligosaccharide which can be isolated from plants such as Jerusalem artichoke, chicory or dahlia, into pure fructose (1). Fructooligosaccharides have great potential in food industry because they can be used as calorie-reduced and noncariogenic sweeteners. Fructose formation from inulin is a single step enzymatic reaction and yields are up to 95% fructose. On contrary, conventional fructose production from starch needs at least three enzymatic steps, yielding only 45% fructose (2). Inulinase production process was optimised by using experimental design method. pH value of the cultivation medium showed to be the most significant variable and it should be maintained at optimum value, 3,5. The effect of temperature was slightly lower and optimal values are between 30 and 35C. At a low pH value of the cultivation medium, the microorganism was not able to produce enough enzyme and enzyme activities were low. Similar effect was caused by high temperature. Highest values of enzyme activities were achieved at optimal fermentation conditions and the figures were: 100,16-124,36 U/ml (with sucrose as substrate for determination of enzyme activity) or 8,6 -11,6 U/ml (with inulin as substrate for determination of enzyme activity), respectively. The method of factorial design and response surface analysis makes it possible to study several factors simultaneously, to quantify the effect of each of them and to investigate their possible interactions (3). As comparison to this method, an analytical optimisation of enzyme activity model depending on pH and temperature was done. Key words: Kluyveromyces bulgaricus, inulin, inulinase, optimisation, response surface method 4167FCE6}A _gmailto:zkurt@pbf.hr;mailto:dvranesic@hotmail.comordptiProf. Z. KurtanjeklrofNormal.Prof. Z. 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Kurtanjek,G:\Radovi\2001\PrimMath_01\Sazetak DV_ZK.doc@C$EƀCJ$b'C$Eƀb'n#%[st   "#$Tap0 1 2 4 5 "@Dhl @dp""""&"P"R"T"V"""""*Hv"@" @ @j@h@ @@@ @@GTimes New HYPERLINK mailto:dvranesic@hotmail.com dvranesic@hotmail.com , , physiological modelling P/ =!"#$%Darija Vraneai, }elimir Kurtanjek Modelling and optimisation of inulinase production by Faculty of Food Technology and Biotechnology University of Zagreb Pierottijeva 6, 10000 Zagreb, CROATIA  HYPERLINK mailto:zkurt@pbf.hr zkurt@pbf.hr 01 4605 294 Darija Vraneai will present poster in English language Key words: In the work are presented surface response and physiological based modelling of ( Applied is the experimental design and surface response method for optimi-sation of temperature and pH on inulinase production cultivated on saccharose in shaking flasks. Th Roman5Symbol3& Arial"qhBtTMtTIX"24 (Optimisation of inulinase production by Prof. Z. KurtanjekProf. Z. 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