Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Department: search.filters.department.İzmir Institute of Technology. BioengineeringSubject: search.filters.subject.Response surface methodology

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  • Article
    Citation - WoS: 22
    Citation - Scopus: 24
    Optimization of Extraction Conditions for Active Components in Equisetum Arvense Extract
    (Ars Docendi, 2013) Uslu, Mehmet Emin; Erdoğan, İpek; Bayraktar, Oğuz; Ateş, Mehmet
    Response surface methodology was applied to predict optimum conditions for equisetum arvense extraction. Central composite design was used to monitor the effects of temperature, stirring speed, ethanol percent, extraction time, solid-liquid ratio on dependent variables such as, extract yield percent, total phenol content, total antioxidant capacity, silicic acid amount. According to the mathematical models obtained from the analysis, the highest values for yield percent, total phenol content, total antioxidant capacity and silicic acid amount were found to be 18.67 %, 123 mg gallic acid gr-1 dry weight extract, 1608 μM TEAC mg-1 dry weight extract and 0.0049 mg silicic acid mg-1 dry weight extract, respectively. The plant extracts were analyzed with HPLC to determine the phenolic content and compositional differences of extracts obtained at different extraction conditions. Plant extracts were also analyzed for their cytotoxic and antimicrobial activities. The high total antioxidant capacity and total phenolic content resulted in an increased cytotoxic effect on fibroblast cells. Equisetum arvense extracts showed antimicrobial activity against Staphylococcus epidermidis and Escherichia coli bacteria, however showed no effect against Candida albicans. © 2013 University of Bucharest.
  • Article
    Citation - WoS: 52
    Citation - Scopus: 62
    Solid-State Production of Polygalacturonase by Aspergillus Sojae Atcc 20235
    (Elsevier Ltd., 2007) Üstok, Fatma Işık; Tarı, Canan; Göğüş, Nihan
    The effect of solid substrates, inoculum and incubation time were studied using response surface methodology (RSM) for the production of polygalacturonase enzyme and spores in solid-state fermentation using Aspergillus sojae ATCC 20235. Two-stage optimization procedure was applied using D-optimal and face-centered central composite design (CCD). Crushed maize was chosen as the solid substrate, for maximum polygalacturonase enzyme activity based on D-optimal design. Inoculum and incubation time were determined to have significant effect on enzyme activity and total spore (p < 0.01) based on the results of CCD. A second order polynomial regression model was fitted and was found adequate for individual responses. All two models provided an adequate R2 of 0.9963 (polygalacturonase) and 0.9806 (spores) (p < 0.001). The individual optimum values of inoculum and incubation time for maximum production of the two responses were 2 × 107 total spores and 5-6 days. The predicted enzyme activity (30.55 U/g solid) and spore count (2.23 × 107 spore/ml) were very close to the actual values obtained experimentally (29.093 U/g solid and 2.31 × 107 spore/ml, respectively). The overall optimum region considering the two responses together, overlayed with the individual optima. Solid-state fermentation provided 48% more polygalacturonase activity compared to submerged fermentation under individually optimized conditions.