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The lignocellulosic biomass is comprised of three major components: cellulose, hemicellulose, and lignin. Among these three, cellulose and hemicellulose were already used for the generation of simple sugars and subsequent value-added products. However, lignin is the least applied material in this regard because of its complex and highly variable nature. Regardless, lignin is the most abundant material, and it can be used to produce value-added products such as lignin-modifying enzymes (LMEs), polyhydroxyalkanoates (PHAs), microbial lipids, vanillin, muconic acid, and many others. This review explores the potential of lignin as the microbial substrate to produce such products. A special focus was given to the different types of lignin and how each one can be used in different microbial and biochemical pathways to produce intermediate products, which can then be used as the value-added products or base to make other products. This review paper will summarize the effectiveness of lignin as a microbial substrate to produce value-added products through microbial fermentations. First, basic structures of lignin along with its types and chemistry are discussed. The subsequent sections highlight LMEs and how such enzymes can enhance the value of lignin by microbial degradation. A major focus was also given to the value-added products that can be produced from lignin.
Attia Iram; Aydin Berenjian; Ali Demirci. A Review on the Utilization of Lignin as a Fermentation Substrate to Produce Lignin-Modifying Enzymes and Other Value-Added Products. Molecules 2021, 26, 2960 .
AMA StyleAttia Iram, Aydin Berenjian, Ali Demirci. A Review on the Utilization of Lignin as a Fermentation Substrate to Produce Lignin-Modifying Enzymes and Other Value-Added Products. Molecules. 2021; 26 (10):2960.
Chicago/Turabian StyleAttia Iram; Aydin Berenjian; Ali Demirci. 2021. "A Review on the Utilization of Lignin as a Fermentation Substrate to Produce Lignin-Modifying Enzymes and Other Value-Added Products." Molecules 26, no. 10: 2960.
Ali Demirci; Edward W Mills; Jonathan A Campbell; Joshua R. Cassar. Pulsed Ultraviolet Light Treatment of Chicken Parts. Meat and Muscle Biology 2021, 1 .
AMA StyleAli Demirci, Edward W Mills, Jonathan A Campbell, Joshua R. Cassar. Pulsed Ultraviolet Light Treatment of Chicken Parts. Meat and Muscle Biology. 2021; ():1.
Chicago/Turabian StyleAli Demirci; Edward W Mills; Jonathan A Campbell; Joshua R. Cassar. 2021. "Pulsed Ultraviolet Light Treatment of Chicken Parts." Meat and Muscle Biology , no. : 1.
Electrolyzed oxidizing water (EOW) is one of the promising novel antimicrobial agents that have recently been proposed as the alternative to conventional decontamination methods such as heat and chemical sanitizers. Acidic EOW with pH ranging from 2 to 5 is regarded most applicable in the antimicrobial treatment of vegetables and meats. Neutral and alkaline electrolyzed water have also been explored in few studies for their applications in the food industry. Neutral electrolyzed water is proposed to solve the problems related to the storage and corrosion effect of acidic EOW. Recently, the research focus has been shifted toward the application of slightly acidic EOW as more effective with some supplemental physical and chemical treatment methods such as ultrasound and UV radiations. The different applications of electrolyzed water range from drinking water and wastewater to food, utensil, and hard surfaces. The recent studies also conclude that electrolyzed water is more effective in suspensions as compared with the food surfaces where longer retention times are required. The commercialization of EOW instruments is not adopted frequently in many countries due to the potential corrosion problems associated with acidic electrolyzed water. This review article summarizes the EOW types and possible mechanism of action as well as highlights the most recent research studies in the field of antimicrobial applications and cleaning. Electrolyzed water can replace conventional chemical decontamination methods in the industry and household. However, more research is needed to know its actual mechanism of antimicrobial action along with the primary concerns related to EOW in the processing of different food products.
Attia Iram; Xinmiao Wang; Ali Demirci. Electrolyzed Oxidizing Water and Its Applications as Sanitation and Cleaning Agent. Food Engineering Reviews 2021, 13, 411 -427.
AMA StyleAttia Iram, Xinmiao Wang, Ali Demirci. Electrolyzed Oxidizing Water and Its Applications as Sanitation and Cleaning Agent. Food Engineering Reviews. 2021; 13 (2):411-427.
Chicago/Turabian StyleAttia Iram; Xinmiao Wang; Ali Demirci. 2021. "Electrolyzed Oxidizing Water and Its Applications as Sanitation and Cleaning Agent." Food Engineering Reviews 13, no. 2: 411-427.
The usage of lignocellulosic biomass in energy production for biofuels and other value-added products can extensively decrease the carbon footprint of current and future energy sectors. However, the infrastructure in the processing of lignocellulosic biomass is not well-established as compared to the fossil fuel industry. One of the bottlenecks is the production of the lignocellulolytic enzymes. These enzymes are produced by different fungal and bacterial species for degradation of the lignocellulosic biomass into its reactive fibers, which can then be converted to biofuel. The selection of an ideal feedstock for the lignocellulolytic enzyme production is one of the most studied aspects of lignocellulolytic enzyme production. Similarly, the fermentation enhancement strategies for different fermentation variables and modes are also the focuses of researchers. The implementation of fermentation enhancement strategies such as optimization of culture parameters (pH, temperature, agitation, incubation time, etc.) and the media nutrient amendment can increase the lignocellulolytic enzyme production significantly. Therefore, this review paper summarized these strategies and feedstock characteristics required for hydrolytic enzyme production with a special focus on the characteristics of an ideal feedstock to be utilized for the production of such enzymes on industrial scales.
Attia Iram; Deniz Cekmecelioglu; Ali Demirci. Ideal Feedstock and Fermentation Process Improvements for the Production of Lignocellulolytic Enzymes. Processes 2020, 9, 38 .
AMA StyleAttia Iram, Deniz Cekmecelioglu, Ali Demirci. Ideal Feedstock and Fermentation Process Improvements for the Production of Lignocellulolytic Enzymes. Processes. 2020; 9 (1):38.
Chicago/Turabian StyleAttia Iram; Deniz Cekmecelioglu; Ali Demirci. 2020. "Ideal Feedstock and Fermentation Process Improvements for the Production of Lignocellulolytic Enzymes." Processes 9, no. 1: 38.
Due to their nutritional value, walnut consumption has been increasing worldwide, however outbreaks caused by walnuts are still of concern. Current chemical methods in walnut industry to prevent pathogenic microorganisms are not preferred by the consumer while thermal treatments may cause undesired flavor. UV light is the portion of the electromagnetic spectrum with wavelengths of 100–400 nm. UV light in the 100–280 nm range has germicidal capabilities. Walnut halves and pieces were inoculated with Salmonella Enteritidis and treated in a pulsed UV light system chamber at three different distances for varying treatment times. Maximum log reduction of 3.18 CFU/g was obtained after pulsed UV treatment at 8 cm for 45 s. Measurement of energy levels revealed an increase in energy and temperature with longer treatment time and shorter distance from the strobe to the sample. Furthermore, quality parameters were assessed to determine the influence of pulsed UV light treatment on the quality of walnuts. The quality results showed no significant differences between control and pulsed UV treated samples. Overall, this study demonstrated that pulsed UV light technology is a promising method to decontaminate walnuts without using any chemicals, which will open doors for the food industry.
Gulten Izmirlioglu; Beining Ouyang; Ali Demirci. Utilization of pulsed UV light for inactivation of Salmonella Enteritidis on shelled walnuts. LWT - Food Science and Technology 2020, 134, 110023 .
AMA StyleGulten Izmirlioglu, Beining Ouyang, Ali Demirci. Utilization of pulsed UV light for inactivation of Salmonella Enteritidis on shelled walnuts. LWT - Food Science and Technology. 2020; 134 ():110023.
Chicago/Turabian StyleGulten Izmirlioglu; Beining Ouyang; Ali Demirci. 2020. "Utilization of pulsed UV light for inactivation of Salmonella Enteritidis on shelled walnuts." LWT - Food Science and Technology 134, no. : 110023.
In this study, various functions were evaluated and utilized to forecast observed values and kinetic parameters of the batch ethanol fabrication from carob extract in the suspended‐cell stirred tank reactor (SCSTR). The best model was detected with the model comparison parameters (root‐mean‐square‐error [RMSE], mean‐absolute‐error [MAE], and R 2 ). The results indicated that the model Stannard (ST) successfully predicted biomass production data (RMSE = 0.26 g L−1, MAE = 0.18 g L−1, and R 2 = 0.9910), ethanol fabrication data (RMSE = 2.44 g L−1, MAE = 1.88 g L−1, and R 2 = 0.9809), and sugar depletion data (RMSE = 2.82 g L−1, MAE = 2.17 g L−1 and R 2 = 0.9938). Nevertheless, the lowest value of the objective function (Φ ‐factor) was also yielded as 0.041 using the model ST. Additionally, in the estimation of the kinetic data, the model ST also gave well‐directed results. Besides, when an independent set of the observed values was utilized to confirm the mathematical functions, the satisfactory consequences were achieved in terms of both the experimental and kinetic values. Consequently, the model ST can work as a universal function in predicting observed values and kinetics of batch ethanol generation from carob extract in an SCSTR.
Mustafa Germec; Mustafa Karhan; Ali Demirci; Irfan Turhan. Mathematical modeling of batch bioethanol generation from carob extract in the suspended‐cell stirred‐tank bioreactor. International Journal of Energy Research 2020, 44, 1 .
AMA StyleMustafa Germec, Mustafa Karhan, Ali Demirci, Irfan Turhan. Mathematical modeling of batch bioethanol generation from carob extract in the suspended‐cell stirred‐tank bioreactor. International Journal of Energy Research. 2020; 44 (11):1.
Chicago/Turabian StyleMustafa Germec; Mustafa Karhan; Ali Demirci; Irfan Turhan. 2020. "Mathematical modeling of batch bioethanol generation from carob extract in the suspended‐cell stirred‐tank bioreactor." International Journal of Energy Research 44, no. 11: 1.
Biofilms in the environment can both detrimental and beneficial effects. On the other hand, biofilms can be useful for wastewater treatment, bioremediation, and removal of toxic pollutants. Furthermore, biofilms can be used for the productions of value-added products (VAPs) such as biofuels, polysaccharides, antibiotics, organic acids, vitamins, and enzymes. To establish biofilms in the reactors, solid support materials (SSMs) made of inorganic compounds and various agricultural by-products. For these, several types biofilm reactors (BRs) have been utilized such as stirred tank biofilm (bio)reactor (STBR), fluidized-bed biofilm (bio)reactor (FBR), fixed/packed-bed biofilm (bio)reactor (PBR), rotary disc biofilm (bio)reactor (RDR)/rotating biological contactor (RBC), membrane biofilm (bio)reactor (MBR), moving bed biofilm (bio)reactor (MBBR) and trickling filter biofilm (bio)reactor (TBR). The benefits of BRs: increase product yield, provide logarithmic phase growth, reduce lag phase and fermentation time for repeated fermentations, increase biomass population, provide resistance toward toxic compounds, and improve product recovery. This review paper will summarize the literature for biofilm formation and structure, BR types, biofilm support materials, and various VAPs-produced by using BRs.
Mustafa Germec; Ali Demirci; Irfan Turhan. Biofilm reactors for value-added products production: An in-depth review. Biocatalysis and Agricultural Biotechnology 2020, 27, 101662 .
AMA StyleMustafa Germec, Ali Demirci, Irfan Turhan. Biofilm reactors for value-added products production: An in-depth review. Biocatalysis and Agricultural Biotechnology. 2020; 27 ():101662.
Chicago/Turabian StyleMustafa Germec; Ali Demirci; Irfan Turhan. 2020. "Biofilm reactors for value-added products production: An in-depth review." Biocatalysis and Agricultural Biotechnology 27, no. : 101662.
Modeling has become an important and efficient tool to predict microbial behavior in food safety and engineering. Foodborne pathogen infections, leading to foodborne illnesses and significant economic losses, are closely associated with public human health. Therefore, various mathematical models have been developed for food safety management, identifying critical control points, evaluating reformulations, and education in food engineering. These models can predict the microbial growth or response in different environments including temperature, moisture, pH, and concentration of preservatives in simulated or actual food systems. In this chapter, the most widely used traditional and novel food microbial predictive models are classified into primary, secondary, and tertiary models. They are introduced specifically for better understanding the theory, function, and systematical applications, as well as the origin, development process, state-of-the-art and the prospects of each model. In addition, the four specific growth models, i.e. Baranyi and Roberts model, square root model, response surface methodology, and artificial neural networks, as well as the software for Integrated Pathogen Modelling Program (IPMP 2013), are described in detail with an emphasis on the basic assumptions, limitations, and possible enhancements. The predictive models have commanded a bigger slice of the food safety engineering, such as in HACCP (Hazard Analysis Critical Control Point) and QMRA (Quantitative Microbiological Risk Assessment) programs with their increasing robustness and improving capabilities.
Ehsan Mahdinia; ShaoWei Liu; Ali Demirci; Virendra M. Puri. Microbial Growth Models. Food Engineering Series 2020, 357 -398.
AMA StyleEhsan Mahdinia, ShaoWei Liu, Ali Demirci, Virendra M. Puri. Microbial Growth Models. Food Engineering Series. 2020; ():357-398.
Chicago/Turabian StyleEhsan Mahdinia; ShaoWei Liu; Ali Demirci; Virendra M. Puri. 2020. "Microbial Growth Models." Food Engineering Series , no. : 357-398.
Food safety is a major concern in food production. Many chemical, physical, and thermal methods currently exist to reduce or eliminate pathogenic and spoilage microorganisms commonly associated with food. However, some of these methods may not be effective enough and can lead to unsafe food, quality deterioration, or undesirable residues. Thus, some alternative food processing methods are being developed and evaluated for the purpose of ensuring microbial food safety for various food applications. Microbial decontamination of food by light-based technologies, including ultraviolet (UV) light, pulsed UV (PUV) light, and UV light-emitting diodes (UV-LED), are alternative microbial intervention methods used for food decontamination. This chapter provides a fundamental understanding of these light-based technologies and explains the microbial inactivation mechanisms. A review of literature includes the effectiveness of UV light-based technologies for food decontamination and addresses the critical factors affecting the microbial decontamination of the technologies. Limitations, regulation and future trends are also discussed.
Joshua R. Cassar; Beining Ouyang; Kathiravan Krishnamurthy; Ali Demirci. Microbial Decontamination of Food by Light-Based Technologies: Ultraviolet (UV) Light, Pulsed UV Light (PUV), and UV Light-Emitting Diodes (UV-LED). Engineering Foods for Bioactives Stability and Delivery 2020, 493 -521.
AMA StyleJoshua R. Cassar, Beining Ouyang, Kathiravan Krishnamurthy, Ali Demirci. Microbial Decontamination of Food by Light-Based Technologies: Ultraviolet (UV) Light, Pulsed UV Light (PUV), and UV Light-Emitting Diodes (UV-LED). Engineering Foods for Bioactives Stability and Delivery. 2020; ():493-521.
Chicago/Turabian StyleJoshua R. Cassar; Beining Ouyang; Kathiravan Krishnamurthy; Ali Demirci. 2020. "Microbial Decontamination of Food by Light-Based Technologies: Ultraviolet (UV) Light, Pulsed UV Light (PUV), and UV Light-Emitting Diodes (UV-LED)." Engineering Foods for Bioactives Stability and Delivery , no. : 493-521.
The correct plant layout, selection of equipment for food processing, the cleaning and sanitation of the processing equipment and the processing plant, are the key factors to ensure food safety. Factors affecting cleaning and sanitization come from different aspects, including physical factors, chemical factors, biological factors as well as environmental factors. A combination of Hazard Analysis Critical Control Point (HACCP), Good Manufacturing Practices (GMP), and Sanitation Standard Operating Procedures (SSOP) serves as the foundation for the cleaning, sanitation, and maintenance of food processing facility and environment. This chapter summarizes the cleaning and sanitation mechanisms and detailed procedures applied in food processing plants, and the cleaning, sanitation, and maintenance of food processing equipment of representative categories.
Xinmiao Wang; Virendra M. Puri; Ali Demirci. Equipment Cleaning, Sanitation, and Maintenance. Engineering Foods for Bioactives Stability and Delivery 2020, 333 -353.
AMA StyleXinmiao Wang, Virendra M. Puri, Ali Demirci. Equipment Cleaning, Sanitation, and Maintenance. Engineering Foods for Bioactives Stability and Delivery. 2020; ():333-353.
Chicago/Turabian StyleXinmiao Wang; Virendra M. Puri; Ali Demirci. 2020. "Equipment Cleaning, Sanitation, and Maintenance." Engineering Foods for Bioactives Stability and Delivery , no. : 333-353.
Distillers’ dried grain with solubles (DDGS) is a byproduct of bioethanol fermentation, which uses the dry milling technology for starch-rich grains such as corn, wheat, and barley. The current interest in bioethanol is increasing due to the need for renewable liquid fuels specifically in the transportation sector. Since DDGS is rich in crude protein, fat, fiber, vitamins, and minerals, it is currently used as aquaculture, livestock, and poultry feeds. In recent years, DDGS has been used as feedstock in the production of value-added products via microbial fermentation. Numerous studies reported the production organic acids, methane, biohydrogen, and hydrolytic enzymes using DDGS. While DDGS contains remarkable amounts of macronutrients, pre-treatment of DDGS is required for release of the fermentable sugars. The pre-treatment methods such as chemical, physical, and biological origin are either solely used or combined to obtain maximal yields for different applications. Therefore, this review summarizes some of the most prominent pre-treatment processes generating high fermentable sugar yields for the productions of value-added products in the last 5 years. A special focus has been given to the effect of the variability of DDGS on the final product. Integration of hydrolytic enzyme production with the traditional bioethanol production facilities has been discussed for further improvement of bioethanol, methane, and biohydrogen using DDGS as fermentation feedstock.
Attia Iram; Deniz Cekmecelioglu; Ali Demirci. Distillers’ dried grains with solubles (DDGS) and its potential as fermentation feedstock. Applied Microbiology and Biotechnology 2020, 104, 6115 -6128.
AMA StyleAttia Iram, Deniz Cekmecelioglu, Ali Demirci. Distillers’ dried grains with solubles (DDGS) and its potential as fermentation feedstock. Applied Microbiology and Biotechnology. 2020; 104 (14):6115-6128.
Chicago/Turabian StyleAttia Iram; Deniz Cekmecelioglu; Ali Demirci. 2020. "Distillers’ dried grains with solubles (DDGS) and its potential as fermentation feedstock." Applied Microbiology and Biotechnology 104, no. 14: 6115-6128.
Unpasteurized liquid egg can be contaminated with pathogenic microorganisms and may cause foodborne outbreaks. Thus, it is essential to decontaminate the liquid egg to ensure food safety. Pulsed UV light is one of the emerging technologies for food decontamination in recent years. This static treatment system has been studied previously in our laboratory. However, continuous processing using a flow-through treatment system needs to be evaluated for potential commercial applications. Therefore, in this study, a flow-through treatment system of pulsed UV light was evaluated and optimized for inactivation of Escherichia coli K12NSR for liquid egg white decontamination. Treatment factors including flow rate (40 to 80 mL/min), number of passes (one to three passes), and distance from the sample to the pulsed UV light strobe (5 to 13 cm) were optimized using response surface methodology. This methodology suggested three passes with 40 mL/min flow rate and a 5-cm distance as the optimum conditions. The model was then validated for the maximum reduction of E. coli K12NSR, which was measured as 1.57 log CFU/mL at the optimal conditions. The energy doses of the pulsed UV light and temperature changes of the liquid egg white during the treatment were measured. Furthermore, several quality parameters were assessed at the optimum treatment conditions to determine the impact of the flow-through pulsed UV processing on the quality of liquid egg white. The results showed significant differences in pH, lipid oxidation, turbidity, and color between control and pulsed UV light-treated samples (P < 0.05). However, there was no significant difference in foaming ability or foam stability between pulsed UV light-treated samples and the control. Overall, this study demonstrated the potential of flow-through pulsed UV light to decontaminate liquid egg white, but further research is needed for optimal enhancement.
Beining Ouyang; Ali Demirci; Paul H. Patterson. Inactivation of Escherichia coli K-12 in Liquid Egg White By a Flow-through Pulsed Uv Light Treatment System. Journal of Food Protection 2020, 83, 418 -425.
AMA StyleBeining Ouyang, Ali Demirci, Paul H. Patterson. Inactivation of Escherichia coli K-12 in Liquid Egg White By a Flow-through Pulsed Uv Light Treatment System. Journal of Food Protection. 2020; 83 (3):418-425.
Chicago/Turabian StyleBeining Ouyang; Ali Demirci; Paul H. Patterson. 2020. "Inactivation of Escherichia coli K-12 in Liquid Egg White By a Flow-through Pulsed Uv Light Treatment System." Journal of Food Protection 83, no. 3: 418-425.
In the present study, eleven flexible models were employed to describe the effect of different medium compositions (DMC) on ethanol fermentation in repeated-batch biofilm reactors with carob extract. Residual-sum of square, root-mean-square-error, mean-absolute-error, determination coefficient, bias factor, accuracy factor, F test, and objective function were used to compare the models. Findings indicated that corresponding with the prediction of the experimental data of substrate concentration (S), the best-selected models were the Baranyi model (media A and C), Weibull model (medium B), and re-modified Gompertz model (R-MGM) (medium D). It was also found that in the estimation of the observed biomass concentration (X) data, Baranyi model (medium A), Weibull model (medium B), and Stannard model (media C and D) gave well-directed results according to the model comparison, validation, and fitting results. As related to ethanol concentration (P), the predicted data with the re-modified Richards model (R-MRM) (media A and B), re-modified logistic model (R-MLM) (medium C), and Baranyi model (medium D) were showed good agreement with the experimental p values. To validate the best-selected models, an independent set of the experimental data for each medium was used and it was found that the independent experimental values were highly compatible with the selected models. Consequently, the best-selected models can serve as universal equations to fit satisfactorily the experimental S, X, and P curves. These models can also be used for further improvement of the carob extract–based bioethanol production process.
Mustafa Germeç; Mustafa Karhan; Ali Demirci; Irfan Turhan. Implementation of flexible models to bioethanol production from carob extract–based media in a biofilm reactor. Biomass Conversion and Biorefinery 2020, 1 -17.
AMA StyleMustafa Germeç, Mustafa Karhan, Ali Demirci, Irfan Turhan. Implementation of flexible models to bioethanol production from carob extract–based media in a biofilm reactor. Biomass Conversion and Biorefinery. 2020; ():1-17.
Chicago/Turabian StyleMustafa Germeç; Mustafa Karhan; Ali Demirci; Irfan Turhan. 2020. "Implementation of flexible models to bioethanol production from carob extract–based media in a biofilm reactor." Biomass Conversion and Biorefinery , no. : 1-17.
Bioenergy is one of the most promising solutions for the environmental problems of using non-renewable energy resources. Bioethanol is a form of bioenergy produced from food crops, such as corn, wheat, and sugarcane. Distillers’ dried grains with solubles (DDGS) is the by-product of corn and wheat ethanol production in the dry mill process and has a high nutritional profile. The undigested carbohydrate components in DDGS and proteins can be utilized as the feedstock to produce microbial cellulases and xylanases as the value-added products. Currently, several bacterial and fungal strains are used to produce such enzymes by using expensive feedstocks for commercial preparations. In this study, several bacterial and fungal strains have been evaluated to explore the potential of hydrolyzed DDGS as the main feedstock for these hydrolytic enzymes production. Maximum cellulase production of 0.592 IU/ml was observed for Aspergillus niger (NRRL 1956) on the eighteenth day and stable high production of xylanase of 34.8 IU/ml was obtained for Aspergillus niger (NRRL 567) on day twelfth during shake-flask fermentation. Hydrolytic enzyme production by Bacillus subtilis (NRRL NSR352, DSM 17766, and NF1) was relatively lower (0–0.261 IU/ml for cellulase and 1.2–5.2 IU/ml for xylanase) than the fungal enzyme production. In conclusion, this study demonstrated that hydrolyzed DDGS can be an alternative economical substrate for A. niger strains to produce cellulase and xylanase, respectively. The next phases of the study should further optimize the production of cellulase and xylanase in terms of growth parameters and medium components by using bench-top bioreactors.
Attia Iram; Deniz Cekmecelioglu; Ali Demirci. Screening of bacterial and fungal strains for cellulase and xylanase production using distillers’ dried grains with solubles (DDGS) as the main feedstock. Biomass Conversion and Biorefinery 2020, 1 -10.
AMA StyleAttia Iram, Deniz Cekmecelioglu, Ali Demirci. Screening of bacterial and fungal strains for cellulase and xylanase production using distillers’ dried grains with solubles (DDGS) as the main feedstock. Biomass Conversion and Biorefinery. 2020; ():1-10.
Chicago/Turabian StyleAttia Iram; Deniz Cekmecelioglu; Ali Demirci. 2020. "Screening of bacterial and fungal strains for cellulase and xylanase production using distillers’ dried grains with solubles (DDGS) as the main feedstock." Biomass Conversion and Biorefinery , no. : 1-10.
Most of the corn-ethanol plants use dry-mill process and generate large volume of distillers dried grains with solubles (DDGS) as the co-product. The DDGS is a promising feedstock with rich content of cellulose and xylan. The goal of this study was to optimize cellulase and xylanase production by Trichoderma reesei (NRRL 6156) using DDGS as the carbon source at shake-flask and validate the results at benchtop bioreactors. The fermentation medium containing varied amounts of dilute-acid pretreated DDGS, yeast extract, and peptone were optimized for maximal enzyme production at 30 °C, pH 5.0 and 180 rpm with 3% (v/v) inoculum using Box-Behnken response surface methodology (RSM). Co-production of xylanase and cellulase enzymes was not achieved in the same medium; higher DDGS hydrolysate favored cellulase enzyme only while lower amount induced the xylanase enzyme. Based on the RSM results, maximal xylanase of 18.5 IU/mL was predicted with 5% DDGS hydrolysate, 0.1 g/L yeast extract, and 2 g/L peptone, while maximal cellulase of 1.1 IU/mL was predicted with 20% DDGS hydrolysate, 1 g/L yeast extract, and 0.5 g/L peptone. Of the two developed models from shake-flasks, xylanase model validated successfully the fermenter results giving 18.7 IU/mL of experimental xylanase in 1.5-L working volume bioreactor.
Deniz Cekmecelioglu; Ali Demirci. Production of Cellulase and Xylanase Enzymes Using Distillers Dried Grains with Solubles (DDGS) by Trichoderma reesei at Shake-Flask Scale and the Validation in the Benchtop Scale Bioreactor. Waste and Biomass Valorization 2020, 11, 6575 -6584.
AMA StyleDeniz Cekmecelioglu, Ali Demirci. Production of Cellulase and Xylanase Enzymes Using Distillers Dried Grains with Solubles (DDGS) by Trichoderma reesei at Shake-Flask Scale and the Validation in the Benchtop Scale Bioreactor. Waste and Biomass Valorization. 2020; 11 (12):6575-6584.
Chicago/Turabian StyleDeniz Cekmecelioglu; Ali Demirci. 2020. "Production of Cellulase and Xylanase Enzymes Using Distillers Dried Grains with Solubles (DDGS) by Trichoderma reesei at Shake-Flask Scale and the Validation in the Benchtop Scale Bioreactor." Waste and Biomass Valorization 11, no. 12: 6575-6584.
Distillers‘ dried grains with solubles (DDGS) are by-products of dry-mill bioethanol production from corn and wheat. The DDGS is leftover by the yeast after converting the starch into ethanol and it has a high nutritional profile including undigested fiber and protein fractions. The DDGS can be used as cheap microbial feedstock for the production of cellulase and xylanases, which are produced from expensive industrial feedstocks. In this study, screening of several bacterial and fungal strains was done using DDGS as the feedstock for the hydrolytic enzyme production. Among all these strains, Aspergillus niger (NRRL 1956) produced the maximum cellulase of 0.592 IU/ml. On the other hand, stable high production of xylanase of 34.8 IU/ml was obtained by Aspergillus niger (NRRL 567) on day twelfth. Bacterial enzyme production by Bacillus subtilis (NRRL NSR352, DSM 17766, and NF1) was relatively lower (0-0.261 IU/ml for cellulase and 1.2-5.2 IU/ml for xylanase) than the fungal enzyme production. In conclusion, this study demonstrated that the hydrolyzed DDGS can be an alternative economical substrate for A. niger strains to produce cellulase and xylanase, respectively. The next phases of the study should further optimize the production of cellulase and xylanase in terms of growth parameters and medium components by using benchtop bioreactors.
Attia Iram; Deniz Cekmecelioglu; Ali Demirci. Bacterial and Fungal Strain Selections for Cellulase and Xylanase Production using Distillers’ Dried Grains with Solubles (DDGS). 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020 2020, 1 .
AMA StyleAttia Iram, Deniz Cekmecelioglu, Ali Demirci. Bacterial and Fungal Strain Selections for Cellulase and Xylanase Production using Distillers’ Dried Grains with Solubles (DDGS). 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020. 2020; ():1.
Chicago/Turabian StyleAttia Iram; Deniz Cekmecelioglu; Ali Demirci. 2020. "Bacterial and Fungal Strain Selections for Cellulase and Xylanase Production using Distillers’ Dried Grains with Solubles (DDGS)." 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020 , no. : 1.
Bacterial cellulose (BC), due to its high porosity, high tensile strength, biocompatibility and crystal structure, can be used as a value-added product in the pharmaceutical, food, and processing industries. Studies have been conducted aimed at enhancing BC production and physical properties. Among all the existing methods, polysaccharide addition is one of the most effective ways to increase the production and to alter the mechanical properties of BC. Agitated fermentation, compared to a conventional static cultivation method, is also reported to enhance the BC production. However, there is a lack of study regarding combining agitated fermentation and polysaccharide additive. Moreover, it might not be practical to use polysaccharides directly in industrial production due to cost considerations. This study evaluated an agitated fermentation with pure pullulan additives and a co-culturing system in which the BC-producing microorganisms (Gluconacetobacter hansenii) grow together with Aureobasidium pullulans, a fungus that produces pullulan as exopolysaccharide (EPS). The study included shake-flask studies, fermentation optimization using response surface methodology (RSM). The research has shown a maximum of 4.5-fold enhancement in the production of BC with pure pullulan addition and a maximum of 6-fold increment for Young‘s modulus with pullulan addition and co-culturing. The study provided a more in-depth understanding of the performance of G. hansenii in agitated and co-culture fermentation systems and could lead to further studies aimed at producing better quality BC products for a variety of applications.
Hetian Hu; Jeffrey M. Catchmark; Ali Demirci. Study of a Novel Co-culturing Fermentation for Bacterial Cellulose Nanocomposite Production. 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020 2020, 1 .
AMA StyleHetian Hu, Jeffrey M. Catchmark, Ali Demirci. Study of a Novel Co-culturing Fermentation for Bacterial Cellulose Nanocomposite Production. 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020. 2020; ():1.
Chicago/Turabian StyleHetian Hu; Jeffrey M. Catchmark; Ali Demirci. 2020. "Study of a Novel Co-culturing Fermentation for Bacterial Cellulose Nanocomposite Production." 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020 , no. : 1.
Conventional processing methods such as heat pasteurization are currently being used to ensure the food safety of liquid eggs. However, alternative methods are needed to improve the decontamination effect and maintain the quality of eggs. In this study, pulsed UV light treatment was evaluated for inactivation of Escherichia coli K12 NSR and Salmonella Enteritidis NSR in liquid egg white under static and flow-through processing systems with different treatment parameters. The temperature of the egg white and energy dose were measured under the two processing systems. Finally, the effects of pulsed UV light treatments on egg quality parameters including pH, color, lipid oxidation, foaming ability, and foam stability were evaluated. In the static system, the maximum log reduction obtained of E. coli K12 NSR was 1.06 log CFU/mL after 40 s pulsed UV light treatment at 5 cm in 7 mL fresh liquid egg white. The maximum log reduction of S. Enteritidis PT8 NSR was 1.76 log CFU/mL at 9cm after 40 s treatment in 5 mL fresh liquid egg white. For the flow-through processing system, the maximum log reduction obtained were 1.43 log CFU/mL for E. coli K12 NSR at 5 cm with 40 mL/min of flow rate and two passes. Overall, this study showed that pulsed UV light can inactivate E. coli K12 NSR and S. Enteritidis NSR in liquid egg white with only minor changes in egg quality.
Beining Ouyang; Ali Demirci; Paul H Patterson. Pulsed UV light inactivation of Escherichia coli and Salmonella in liquid egg white and its effects on quality. 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020 2020, 1 .
AMA StyleBeining Ouyang, Ali Demirci, Paul H Patterson. Pulsed UV light inactivation of Escherichia coli and Salmonella in liquid egg white and its effects on quality. 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020. 2020; ():1.
Chicago/Turabian StyleBeining Ouyang; Ali Demirci; Paul H Patterson. 2020. "Pulsed UV light inactivation of Escherichia coli and Salmonella in liquid egg white and its effects on quality." 2020 ASABE Annual International Virtual Meeting, July 13-15, 2020 , no. : 1.
E. Mahdinia; Ali Demirci; A. Berenjian. Evaluation of vitamin K (menaquinone-7) stability and secretion in glucose and glycerol-based media by Bacillus subtilis natto. Acta Alimentaria 2019, 48, 405 -414.
AMA StyleE. Mahdinia, Ali Demirci, A. Berenjian. Evaluation of vitamin K (menaquinone-7) stability and secretion in glucose and glycerol-based media by Bacillus subtilis natto. Acta Alimentaria. 2019; 48 (4):405-414.
Chicago/Turabian StyleE. Mahdinia; Ali Demirci; A. Berenjian. 2019. "Evaluation of vitamin K (menaquinone-7) stability and secretion in glucose and glycerol-based media by Bacillus subtilis natto." Acta Alimentaria 48, no. 4: 405-414.
This study evaluated the pulsed UV light treatment for the inactivation of Escherichia coli K12 and Salmonella Enteritidis in liquid egg white. Three parameters (treatment time, volume of liquid egg white, and distance from the sample to the pulse UV strobe) have been optimized for log reductions of microorganisms using response surface methodology. The maximum log reductions obtained after 40 s of treatment time at a 5 cm of distance (the energy dose equals 45.6 J/cm2) were 1.28 log CFU/ml of E. coli K12 and 1.98 log CFU/ml of S. Enteritidis in 5 ml of fresh liquid egg white. A significant temperature increase of the egg white sample (from 24 to 70°C) was observed at the extreme treatment condition (5 cm, 40 s). Quality evaluations indicate that pulsed UV light does not change foaming ability or foam stability of liquid egg white. However, the changes in pH, lipid oxidation, turbidity, and color of the egg white were correlated with the intensity of the treatment. Practical applications Heat pasteurization is currently being used to decontaminate liquid egg white. However, alternative methods are desired to improve decontamination as well as maintain the quality of liquid egg white. This study demonstrated the potential of pulsed UV light for the inactivation of pathogens in liquid egg white.
Beining Ouyang; Ali Demirci; Paul H. Patterson. Inactivation of Escherichia coli and Salmonella in liquid egg white by pulsed UV light and its effects on quality. Journal of Food Process Engineering 2019, 43, 1 .
AMA StyleBeining Ouyang, Ali Demirci, Paul H. Patterson. Inactivation of Escherichia coli and Salmonella in liquid egg white by pulsed UV light and its effects on quality. Journal of Food Process Engineering. 2019; 43 (5):1.
Chicago/Turabian StyleBeining Ouyang; Ali Demirci; Paul H. Patterson. 2019. "Inactivation of Escherichia coli and Salmonella in liquid egg white by pulsed UV light and its effects on quality." Journal of Food Process Engineering 43, no. 5: 1.