Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 18Citation - Scopus: 19Control of Agitation Rate and Aeration for Enhanced Polygalacturonase Production in Submerged Fermentation by Aspergillus Sojae Using Agro-Industrial Wastes(John Wiley and Sons Inc., 2017) Fratebianchi, Dante; Crespo, Juan Manuel; Tarı, Canan; Cavalitto, SebastianBACKGROUND: The koji mold Aspergillus sojae, an industrially important microorganism, can produce high levels of pectinases utilizing agro-industrial wastes. This study introduces apricot and peach pomace, two agro-industrial wastes barely considered as raw material for the generation of value-added products, and focuses on its utilization together with orange peel for polygalacturonase production in submerged cultures using A. sojae. RESULTS: A Doehlert response surface methodology design conducted in shake flasks and applied individually with these three by-products led to 60–80 U mL−1 polygalacturonase activity. In bioreactor studies performed with a mixture of apricot pomace and orange peel, by fixing stirrer speed to 600 rpm and cascading airflow to the dissolved oxygen tension up to 1.7 vvm, oxygen limitation problems were overcome and polygalacturonase activity values of 380 U mL−1 were achieved. CONCLUSION: A simple and efficient strategy to minimize oxygen limitation with the lowest possible shear stress is provided for stirred-tank bioreactors working with highly viscous broths, so as to ultimately enhance microbial enzyme production. The polygalacturonase activity yields obtained in our study are among the highest reported in the literature.Article Citation - WoS: 3Citation - Scopus: 4Evaluation of Agro-Industrial Wastes, Their State, and Mixing Ratio for Maximum Polygalacturonase and Biomass Production in Submerged Fermentation(Taylor and Francis Ltd., 2015) Göğüş, Nihan; Evcan, Ezgi; Tarı, Canan; Cavalitto, Sebastian F.The potential of important agro-industrial wastes, apple pomace (AP) and orange peel (OP) as C sources, was investigated in the maximization of polygalacturonase (PG), an industrially significant enzyme, using an industrially important microorganism Aspergillus sojae. Factors such as various hydrolysis forms of the C sources (hydrolysed-AP, non-hydrolysed-AP, hydrolysed-AP + OP, non-hydrolysed-AP + OP) and N sources (ammonium sulphate and urea), and incubation time (4, 6, and 8 days) were screened. It was observed that maximum PG activity was achieved at a combination of non-hydrolysed-AP + OP and ammonium sulphate with eight days of incubation. For the pre-optimization study, ammonium sulphate concentration and the mixing ratios of AP + OP at different total C concentrations (9, 15, 21 g-1) were evaluated. The optimum conditions for the maximum PG production (144.96 ml-1) was found as 21 g-1 total carbohydrate concentration totally coming from OP at 15 g-1 ammonium sulphate concentration. On the other hand, 3:1 mixing ratio of OP + AP at 11.50 g-1 ammonium sulphate concentration also resulted in a considerable PG activity (115.73 ml-1). These results demonstrated that AP can be evaluated as an additional C source to OP for PG production, which in turn both can be alternative solutions for the elimination of the waste accumulation in the food industry with economical returns.Article Citation - WoS: 13Citation - Scopus: 14Evaluation of Orange Peel, an Industrial Waste, for the Production of Aspergillus Sojae Polygalacturonase Considering Both Morphology and Rheology Effects(TUBITAK, 2014) Gögüş, Nihan; Hakgüder Taze, Bengi; Demir, Hande; Tarı, Canan; Ünlütürk, Sevcan; Lahore, Marcelo FernandezOrange peel is an agroindustrial waste rich in pectin and known to be an inducer for pectinase production. The use of this low-cost substrate for the production of an industrially important enzyme, polygalacturonase (PG), can be an alternative way to turn this waste into a value-added product, contributing to the reduction of environmental waste disposal problems. Enzyme productions by fungal microorganisms are affected by environmental and nutritional factors, demanding the determination of optimum conditions for maximum enzyme production with the desired fungal morphology and broth rheology. Therefore, complex and additional carbon sources were optimized with respect to PG production by Aspergillus sojae using statistical approaches. Effect of pH, another significant parameter affecting the rheology and morphology of the strain, was investigated in the serial bioreactor system using the optimized medium composition. Highest PG enzyme yield and productivity together with the maximum PG enzyme production (93.48 U/mL) were obtained under uncontrolled pH conditions. Under these conditions, morphologically, pellet sizes exhibited a normal distribution ranging between 0.5-1.0 mm and 1.0-1.5 mm, and rheological measurements revealed that fermentation broths showed non-Newtonian flow. The low pH trend observed during the course of the fermentation was another important positive outcome for industrial fermentations, prone to contamination problems.Article Citation - WoS: 28Citation - Scopus: 32Optimization of the Process Parameters for the Utilization of Orange Peel To Produce Polygalacturonase by Solid-State Fermentation From an Aspergillus Sojae Mutant Strain(TUBITAK, 2012) Demir, Hande; Göğüş, Nihan; Tarı, Canan; Heerd, Doreen; Lahore, Marcelo FernandezThe effect of orange peel concentration, HCl concentration, incubation time and temperature, and inoculum size on the spore count and activity of polygalacturonase (PG) enzyme produced from Aspergillus sojae M3 by solidstate fermentation was screened using 2k factorial design. Orange peel and HCl concentrations and incubation time were significant factors affecting the responses. Optimum conditions favoring both PG and spore production from Aspergillus sojae M3 were determined as 2% orange peel and 50 mM HCl concentrations at 22 °C and 4.3 days of incubation. An overlay plot was constructed for use as a practical chart for production of high enzyme activity (>35.0 U/g substrate) and spore count (9.0 × 108 to 2.0 × 109 spore/mL) by superimposing the contours of PG activity and spore count responses. The accuracy and reliability of the constructed models on the responses was validated with the maximum calculated error rate between the predicted and actual activities at 14.1% and 22.4%, respectively. © TÜBİTAK.Article Citation - WoS: 3Citation - Scopus: 5Production of Food Grade Ss-Galactosidase From Artisanal Yogurt Strains(Taylor and Francis Ltd., 2010) Tarı, Canan; Üstok, Fatma Işık; Harsa, ŞebnemSuperior artisanal isolates of thermophilic lactic acid bacteria producing high lactic acid and β-galactosidase were isolated from traditional Turkish yogurt samples from the Toros mountain region from a highly bio-diverse environment. A full factorial statistical design, with the factors of types of strains and medium formulations under static and agitation conditions, were applied to investigate the effects on β-galactosidase and lactic acid production. Streptococcus thermophilus 95/2 and Lactobacillus delbrueckii subsp. thermophilus 77 exhibited remarkable potential as promising starter culture candidates valuable to various applications in the dairy industry. The efficiency of cell disruption methods was investigated on the extraction of intracellular β-galactosidase enzyme. Lysozyme enzyme treatment was determined as the most effective method, which resulted in approximately 1.5 and 10 times higher enzyme activity than glass bead and homogenization treatment, respectively. © Taylor & Francis Group, LLC.Article Citation - WoS: 10Citation - Scopus: 11Colloid Deposition Experiments as a Diagnostic Tool for Biomass Attachment Onto Bioproduct Adsorbent Surfaces(John Wiley and Sons Inc., 2008) Tarı, Canan; Vennapusa, Rami Reddy; Cabrera, Rosa B.; Fernandez-Lahore, MarceloBackground: Detrimental processing conditions can be expected in any downstream operation where direct contacting between a crude feedstock and a reactive solid phase is supposed to occur. In this paper we have investigated the factors influencing intact yeast cells deposition onto anion and cation exchangers currently utilized for expanded-bed adsorption of biotechnological products. The aim of this study was twofold: (a)to confirm previous findings relating biomass deposition with surface energetics according to the extended Derjaguin, Landau, Verwey and Overbeek theory (XDLVO) theory; and (b) to provide a simple experimental tool to evaluate biomass deposition onto process surfaces. Results: Biomass deposition experiments were performed on an automated workstation utilizing a packedbed format. Two commercial ion exchangers intended for the direct capture of bioproducts in the presence of suspended biological particles were employed. Intact yeast cells in the late exponential phase of growth were selected as model bio-colloids. Cell deposition was systematically evaluated as a function of fluid-phase conductivity and quantitatively expressed as a biomass deposition parameter (α). Conclusion: α ≤ 0.15 was established as a criterion to reflect negligible biomass adhesion to the process support(s). Biomass deposition experiments further confirmed predictions made on the basis of free interfacial energy calculations as per the extended DLVO approach.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.