Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 76Citation - Scopus: 90Optimization of a Growth Medium Using a Statistical Approach for the Production of an Alkaline Protease From a Newly Isolated Bacillus Sp. L21(Elsevier Ltd., 2006) Tarı, Canan; Gençkal, Hande; Tokatlı, FigenBacillus sp. L21 was isolated from the by-products of a leather factory (located in Izmir, Turkey) working under extreme alkaline conditions. Its phenotypic and genotypic identifications were completed, and determined as a potential alkaline protease producer. After screening various elements, carbon and nitrogen sources, soybean meal, maltose50, tween80 and the initial pH conditions were chosen as main factors to be used in the experimental design and response surface methodology (RSM) for the optimization of a low cost enzyme producing media for potential use on an industrial scale. The optimized values obtained by the statistical analysis showed that soybean meal at 3.0 g/l, maltose50 between the ranges of 30 and 40 g/l, tween80 at 0.35 g/l and an initial pH of 8.0 gives maximum protease activity.Article Citation - WoS: 33Citation - Scopus: 37Relationship Between Morphology, Rheology and Polygalacturonase Production by Aspergillus Sojae Atcc 20235 in Submerged Cultures(Elsevier Ltd., 2006) Göğüş, Nihan; Tarı, Canan; Öncü, Şelale; Ünlütürk, Sevcan; Tokatlı, FigenA full factorial statistical design, with the factors of, two taxonomically different strains, seven types of seed culture formulations (slants) and two types of fermentation media were used to investigate the effect of these parameters on the morphology and polygalacturonase production. The rheology of the final fermentation medium was analyzed and appropriate mathematical model was applied to calculate suspension viscosity. It was found that most fermentation broths showed non-Newtonian flow behavior. According to statistical analysis, factors of strain types and fermentation media and the interaction between them were found significant on the enzyme activity. The effect of seed culture formulations (slants) were found insignificant at the significance level of 1%. Interaction of slants with strain types and fermentation media were also found insignificant. Considering the morphology of the final culture, Aspergillus sojae with the desired pellet morphology in a complex media, inoculated with a seed culture prepared from molasses resulted in maximum polygalacturonase enzyme activity (0.2 U/ml) and lowest suspension viscosity with a broth rheology close to Newtonian flow behavior.Article Citation - WoS: 30Citation - Scopus: 42Effect of Various Process Parameters on Morphology, Rheology, and Polygalacturonase Production by Aspergillus Sojae in a Batch Bioreactor(American Institute of Chemical Engineers, 2007) Öncü, Şelale; Tarı, Canan; Ünlütürk, SevcanThe effects of pH, agitation speed, and dissolved oxygen tension (DOT), significant in common fungal fermentations, on the production of polygalacturonase (PG) enzyme and their relation to morphology and broth rheology were investigated using Aspergillus sojae in a batch bioreactor. All three factors were effective on the response parameters under study. An uncontrolled pH increased biomass and PG activity by 27% and 38%, respectively, compared to controlled pH (pH 6) with an average pellet size of 1.69 ± 0.48 mm. pH did not significantly affect the broth rheology but created an impact on the pellet morphology. Similarly, at constant agitation speed the maximum biomass obtained at 500 rpm and at 30 h was 3.27 and 3.67 times more than at 200 and 350 rpm, respectively, with an average pellet size of 1.08 ± 0.42 mm. The maximum enzyme productivity of 0.149 U mL-1 h-1 was obtained at 200 rpm with an average pellet size of 0.71 ± 0.35 mm. Non-Newtonian and pseudoplastic broth rheology was observed at 500 rpm agitation speed, broth rheology exhibited dilatant behavior at the lower agitation rate (200 rpm), and at the medium agitation speed (350 rpm) the broth was close to Newtonian. Furthermore, a DOT range of 30-50% was essential for maximum biomass formation, whereas only 10% DOT was required for maximum PG synthesis. Non-Newtonian shear thickening behavior (n > 1.0) was depicted at DOT levels of 10% and 30%, whereas non-Newtonian shear thinning behavior (n < 1.0) was dominant at 50% DOT. The overall fermentation duration (50-70 h) was considerably shorter compared to common fungal fermentations, revealing the economic feasibility of this particular process. As a result this study not only introduced a new strain with a potential of producing a highly commercially significant enzyme but also provided certain parameters significant in the design and mathematical modeling of fungal bioprocesses.