Food Engineering / Gıda Mühendisliği

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Citation - WoS: 58
Citation - Scopus: 70
Antioxidant and Antimicrobial Activities of Thyme and Clove Essential Oils and Application in Minced Beef
(John Wiley and Sons Inc., 2015-12) Zengin, Hatice; Baysal, Ayşe Handan; Baysal, Ayşe Handan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this study, thyme and clove essential oils (EOs) were studied for their chemical composition, antioxidant, antiradical and antibacterial activity and application in ground beef. Carvacrol (75.27%) and eugenol (75.2%) were detected by gas chromatography-mass spectrometry analysis as the main components of thyme and clove EOs, respectively. Broth microdilution method showed all bacteria inhibited by the EOs, while Shewanella putrefaciens and Listeria innocua were the most resistant bacteria to thyme and clove EOs, respectively. EO treatment restricted the growth of artificially inoculated Salmonella typhimurium and native Coliforms in the ground beef. Antioxidant activity determined by ferric-reducing antioxidant power and 1,1 diphenyl-2-picrylhydrazyl methods demonstrated that clove EO had higher in vitro antioxidant activity than thyme EO. Similar results were obtained in ground beef application using 2-thiobarbituric acid value. EOs of clove (2MIC) exerted remarkable higher antioxidant activity in ground beef than EOs of thyme (4MIC), which represent valid alternative antioxidant in meat products. Practical Applications: Plant essential oils (EOs) serve as a "safe" alternative to chemical or synthetic antimicrobials and antioxidants to struggle with the foodborne pathogens or spoilage organisms, inhibiting lipid oxidation and thus extending shelf life. Antioxidant activity determined by ferric-reducing antioxidant power and 1,1 diphenyl-2-picrylhydrazyl methods showed that clove EO had higher in vitro antioxidant activity than thyme EO. Results obtained using 2-thiobarbituric acid value in ground beef application were found similar. EOs of clove (2MIC) exerted higher antioxidant activity in ground beef than EOs of thyme (4MIC). Therefore, EOs could be a valid alternative antioxidant in meat products.
Citation - WoS: 32
Citation - Scopus: 36
Application of Mid-Infrared Spectroscopy for the Measurement of Several Quality Parameters of Alcoholic Beverages, Wine and Raki
(Springer Verlag, 2012-12) Öztürk, Burcu; Özen, Fatma Banu; Yücesoy, Dila; Özen, Banu; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Mid-infrared (IR) spectroscopy, which is a rapid and relatively small amount of waste producing technique, was used to predict several quality parameters of two types of alcoholic beverages, wine and raki. Mid-infrared spectra of red, rose and white wines and a traditional aniseed alcoholic beverage, raki were collected and relations were established between measured chemical parameters (pH, brix, total phenol content, anthocyanin content, titratable acidity, sugar content, electrical conductivity and some colour parameters) of these beverages and their infrared spectra using chemometric techniques. Partial least square regression provided excellent prediction of total phenol (R 2 = 0. 97) and anthocyanin contents (R 2 = 0. 98) of wine samples and a good prediction of pH (R 2 = 0. 9), brix (R 2 = 0. 92) and colour intensity (R 2 = 0. 93) values were obtained. Brix, total phenol and sugar content of raki samples were also estimated very successfully (R 2 = 0. 99) for raki and good prediction was obtained with pH value. Mid-IR spectroscopy in combination with chemometrics could be a promising technique for determination of several quality parameters of alcoholic beverages simultaneously and rapidly.
Citation - WoS: 16
Citation - Scopus: 15
Characterization of Silk Fibroin Based Films Loaded With Rutin-Ss Inclusion Complexes
(Kluwer Academic Publishers, 2014-10) Şamlı, Merve; Bayraktar, Oğuz; Bayraktar, Oğuz; Korel, Figen; Korel, Figen; 03.08. Department of Food Engineering; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this study, cyclodextrin inclusion complexes with rutin were prepared via co-precipitation method. Stability constant and solubility energy of beta-cyclodextrin complex were calculated as 262 M-1 and 1,737 kJ mol-1, respectively. Aqueous solubility of rutin was increased with inclusion complex of beta-cyclodextrin. The effect of temperature on both aqueous solubility of free rutin, and its inclusion complex was also studied. Characterization of cyclodextrin complexes were conducted with UV-Vis spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffractometry, differential scanning calorimetry, thermal gravimetric analysis, nuclear magnetic resonance spectroscopy and scanning electron microscopy techniques. Characterization results supported formation of inclusion complexes. Dissolution profiles of rutin, physical mixture and inclusion complex of rutin were observed at 37 °C. Dissolution results proved the effect of cyclodextrin addition on solubility rate of rutin. After loading rutin and its complexes into silk fibroin based films, release tests were performed at 37 °C in neutral pH conditions for 24 h. Most of the rutin were released from silk fibroin films within the first 5 h and the rest of it was released slowly (sustained release). Electron microscope analyses showed that films had homogenous and dense morphologies. These results revealed that silk fibroin is useful for preparing bioactive films loaded with natural compounds and for modifying their release behaviour at physiological conditions.
Citation - WoS: 5
Citation - Scopus: 6
Chemometric Studies on Znose™ and Machine Vision Technologies for Discrimination of Commercial Extra Virgin Olive Oils
(John Wiley and Sons Inc., 2015-09) Kadiroğlu, Pınar; Korel, Figen; Korel, Figen; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The aim of this study was to classify Turkish commercial extra virgin olive oil (EVOO) samples according to geographical origins by using surface acoustic wave sensing electronic nose (zNose™) and machine vision system (MVS) analyses in combination with chemometric approaches. EVOO samples obtained from north and south Aegean region were used in the study. The data analyses were performed with principal component analysis class models, partial least squares-discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA). Based on the zNose™ analysis, it was found that EVOO aroma profiles could be discriminated successfully according to geographical origin of the samples with the aid of the PLS-DA method. Color analysis was conducted as an additional sensory quality parameter that is preferred by the consumers. The results of HCA and PLS-DA methods demonstrated that color measurement alone was not an effective discriminative factor for classification of EVOO. However, PLS-DA and HCA methods provided clear differentiation among the EVOO samples in terms of electronic nose and color measurements. This study is significant from the point of evaluating the potential of zNose™ in combination with MVS as a rapid method for the classification of geographically different EVOO produced in industry.
Citation - WoS: 14
Citation - Scopus: 16
Classification of Turkish Extra Virgin Olive Oils by a Saw Detector Electronic Nose
(John Wiley and Sons Inc., 2011-05) Kadiroğlu, Pınar; Korel, Figen; Korel, Figen; Tokatlı, Figen; Tokatlı, Figen; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
An electronic nose (e-nose), in combination with chemometrics, has been used to classify the cultivar, harvest year, and geographical origin of economically important Turkish extra virgin olive oils. The aroma fingerprints of the eight different olive oil samples [Memecik (M), Erkence (E), Gemlik (G), Ayvalik (A), Domat (D), Nizip (N), Gemlik-Edremit (GE), Ayvalik-Edremit (AE)] were obtained using an e-nose consisting a surface acoustic wave detector. Data were analyzed by principal component analysis (PCA) and discriminant function analysis (DFA). Classification of cultivars using PCA revealed that A class model was correctly discriminated from N in two harvest years. The DFA classified 100 and 97% of the samples correctly according to the cultivar in the 1st and 2nd harvest years, respectively. Successful separation among the harvest years and geographical origins were obtained. Sensory analyses were performed for determining the differences in the geographical origin of the olive oils and the preferences of the panelists. The panelists could not detect the differences among olive oils from two different regions. The cultivar, harvest year, and geographical origin of extra virgin olive oils could be discriminated successfully by the e-nose.
Citation - WoS: 2
Citation - Scopus: 2
Comparison of Conventional Culture Method and Fluorescent in Situ Hybridization Technique for Detection of Listeria Spp. in Ground Beef, Turkey, and Chicken Breast Fillets in Izmir, Turkey
(International Association for Food Protection, 2014-12) Baysal, Ayşe Handan; Baysal, Ayşe Handan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The occurrence of Listeria species in refrigerated fresh chicken breast fillet, turkey breast fillet, and ground beef was evaluated, comparing the conventional culture method and fluorescent in situ hybridization (FISH). FISH uses hybridization of a nucleic acid sequence target of a microorganism with a specific DNA probe labeled with a fluorochrome and imaging by a fluorescence microscope. First, Listeria was inoculated in chicken breast fillet, turkey breast fillet, or ground beef, and the applicability of the FISH method was evaluated. Second, Listeria was detected in fresh chicken breast fillet, turkey breast fillet, and ground beef by culture and FISH methods. Listeria was isolated from 27 (37.4%) of 216 samples by the standard culture method, whereas FISH detected 25 (24.7%) preenriched samples. Of these isolates, 17 (63%) were L. innocua, 6 (22%) L. welshimeri, and 4 (14.8%) L. seeligeri. Overall, the prevalences of Listeria spp. found with the conventional culture method in chicken breast fillet, turkey breast fillet, and ground beef were 9.7, 6.9, and 20.8%, whereas with the FISH technique these values were 11.1, 6.9, and 16.7%, respectively. The molecular FISH technique appears to be a cheap, sensitive, and time-efficient procedure that could be used for routine detection of Listeria spp. in meat. This study showed that retail raw meats are potentially contaminated with Listeria spp. and are, thus, vehicles for transmitting diseases caused by foodborne pathogens, underlining the need for increased precautions, such as implementation of hazard analysis and critical control points and consumer food safety education.
Citation - WoS: 36
Citation - Scopus: 38
Comparison of Fatty Acid Profiles and Mid-Infrared Spectral Data for Classification of Olive Oils
(John Wiley and Sons Inc., 2010-02) Gürdeniz, Gözde; Tokatlı, Figen; Özen, Banu; Özen, Fatma Banu; Tokatlı, Figen; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The composition of olive oils may vary depending on environmental and technological factors. Fatty acid profiles and Fourier-transform infrared (FT-IR) spectroscopy data in combination with chemometric methods were used to classify extra-virgin olive oils according to geographical origin and harvest year. Oils were obtained from 30 different areas of northern and southern parts of the Aegean Region of Turkey for two consecutive harvest years. Fatty acid composition data analyzed with principal component analysis was more successful in distinguishing northern olive oil samples from southern samples compared to spectral data. Both methods have the ability to differentiate olive oil samples with respect to harvest year. Partial least squares (PLS) analysis was also applied to detect a correlation between fatty acid profile and spectral data. Correlation coefficients (R2) of a calibration set for stearic, oleic, linoleic, arachidic and linolenic acids were determined as 0.83, 0.97, 0.97, 0.83 and 0.69, respectively. Fatty acid profiles were very effective in classification of oils with respect to geographic origin and harvest year. On the other hand, FT-IR spectra in combination with PLS could be a useful and rapid tool for the determination of some of the fatty acids of olive oils.
Citation - WoS: 3
Citation - Scopus: 4
Comparison of Radio-Guided Occult Lesion Localization (roll) and Magnetic Occult Lesion Localization (moll) for Non-Palpable Lesions: a Phantom Model Study
(Elsevier, 2020) Aydoğan, Tumay; Sezgin, Efe; Sezgin, Efe; İlvan, Şennur; Yılmaz, Osman Cem; Aslan, Nesrin; Golshan, Mehra; Aydoğan, Fatih; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
We sought to compare radio-guided localization and magnetic tracer localization techniques by using a phantom model for excision of nonpalpable breast lesions. There was no difference between the groups in the duration of operative excision, specimen weight, or specimen volume. Magnetic occult lesion localization can be performed in clinics without the need for a nuclear medicine team and radiation safety procedures. Background: Localization of nonpalpable breast cancers can be achieved with several techniques. We sought to compare radio-guided localization (ROLL) and magnetic tracer localization (MOLL) techniques by using a phantom model we previously developed, which can provide an accurate simulation for excision of nonpalpable breast lesions. Materials and Methods: We designed 20 phantom models (10 MOLL, 10 ROLL group) for localization. A handheld gamma probe for the ROLL group and a manual magnetometer (SentiMag) for the MOLL group were used to test the ability of the modality to detect olives in turkey breasts. The excision time for each procedure, specimen size, and weight of the specimens removed from the turkey breasts were recorded. Results: Both techniques resulted in 100% retrieval of the lesions. There was no difference between the groups in the duration of operative excision, specimen weight, or specimen volume. Conclusion: This experimental trial found similar success rates for ROLL and MOLL in localization of occult lesions using the turkey breast phantom model. MOLL can be performed in clinics without the need for a nuclear medicine team and radiation safety procedures. (C) 2019 Elsevier Inc. All rights reserved.
Citation - WoS: 17
Citation - Scopus: 20
Composition, Color and Mechanical Characteristics of Pretreated Candied Chestnuts
(Taylor and Francis Ltd., 2006-09) Korel, Figen; Korel, Figen; Balaban, Murat Ömer; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Raw-peeled chestnuts were treated with citric acid or sodium metabisulphite, steamed, and dipped into sugar solutions containing dextrose and sucrose, or dextrose and fructose. Composition, mineral content, weight change, rheological properties, and color were measured at each step. Carbohydrate content increased during processing. Candied chestnuts were low in protein (1.31-1.35%) and lipids (0.29-0.78%) but high in carbohydrates (73.48-76.13%). Their mineral concentrations were: Ca 19.08-46.70, Cu 0.19-0.52, Fe 0.88-1.98, K 180.5-659.1, Mg 26.83-69.57, Mn 0.70-2.42, Zn 1.51-6.95 mg/100 g sample. Rheological properties were affected by processing steps. Dipping into sugar solutions did not affect rheological properties. Color changes were quantified, and average L*, a*, and b*values measured.
Citation - WoS: 66
Citation - Scopus: 74
Differentiation of Mixtures of Monovarietal Olive Oils by Mid-Infrared Spectroscopy and Chemometrics
(John Wiley and Sons Inc., 2007) Gürdeniz, Gözde; Tokatlı, Figen; Tokatlı, Figen; Özen, Fatma Banu; Özen, Fatma Banu; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Fourier transform infrared (FT-IR) spectroscopy in combination with chemometric techniques has become a useful tool for authenticity determination of extra-virgin olive oils. Spectroscopic analysis of monovarietal extra-virgin olive oils obtained from three different olive cultivars (Erkence, Ayvalik and Nizip) and mixtures (Erkence-Nizip and Ayvalik-Nizip) of monovarietal olive oils was performed with an FT-IR spectrometer equipped with a ZnSe attenuated total reflection sample accessory and a deuterated tri-glycine sulfate detector. Using spectral data, principal component analysis successfully classified each cultivar and differentiated the mixtures from pure mono-varietal oils. Quantification of two different monovarietal oil mixtures (2-20%) is achieved using partial least square (PLS) regression models. Correlation coefficients (R2) of the proposed PLS regression models are 0.94 and 0.96 for the Erkence-Nizip and Ayvalik-Nizip mixtures, respectively. Cross-validation was applied to check the goodness of fit for the PLS regression models, and R 2 of the cross-validation was determined as 0.84 and 0.91, respectively, for the two mixtures.
Citation - WoS: 2
Citation - Scopus: 2
The Effect of Ankaferd Blood Stopper on Colonic Inflammation: an in Vitro Study in Raw 264.7 and Caco-2 Cells
(Mary Ann Liebert Inc., 2021) Alyamaç, Ayşegül; Güleç, Şükrü; Özel Taşcı, Cansu; Güleç, Şükrü; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Ankaferd Blood Stopper (ABS) is a medicinal plant extract that has anti-inflammatory effect. Inflammatory bowel disease is a pathological condition that directly affects colon health and increases the risk of colon cancer. Especially inflammation is an important factor in the formation and progression of this disease. The aim of the study was to investigate the protective effect of ABS on colonic inflammation. Caco-2 and RAW 264.7 cells were used as a model of in vitro colonic inflammation. RAW 264.7 cells were treated with lipopolysaccharide for 12 h to induce inflammation, and an inflammatory medium (IM) was obtained. Caco-2 cells were treated with 15 mu L/mL ABS for 4 h, then incubated with IM. The cells also were incubated with 15 mu L/mL ABS and IM together for 12 h. Tumor necrosis factor alpha (TNF-alpha) protein levels were targeted in testing inflammatory condition and cyclooxygenase-2 (COX-2) mRNA level was used as a marker gene to show the possible anti-inflammatory effect of ABS in Caco-2 cells. TNF-alpha level was 26.1-fold higher than the control group. IM caused 3.2-fold increase in COX-2 expression in Caco-2 cells. Pretreatment of Caco-2 cells with ABS resulted in 3.3-fold decrease in COX-2 mRNA levels relative to IM group. Furthermore, COX-2 mRNA level reduced 4.7-fold when ABS and conditional medium were given at the same time. ABS has suppressive effect on COX-2 mRNA expression in Caco-2 cells. These results suggest that ABS might have protective and therapeutic effect for colonic inflammation.
Citation - WoS: 10
Citation - Scopus: 9
Effect of Pretreatments on Microbial Growth and Sensory Properties of Dry-Salted Olives
(International Association for Food Protection, 2014-09) Değirmencioğlu, Nurcan; Gürbüz, Ozan; Değirmencioğlu, Ali; Yıldız, Semanur
The effect of various washing solutions (acetic acid, lactic acid, and chlorine dioxide) and NaCl concentrations (2.5, 5.0, and 10.0%) on the stability of dry-salted olives (cultivars Gemlik and Edincik) during storage was studied. Vacuum-packed olives were stored at 4°C for 7 months and monitored for microbiological changes that occurred in the dry-salted olives during the drysalting process and for their stability during storage. Microbial populations were enumerated using pour plating (for aerobic plate counts) and spread plating (for counts of lactic acid bacteria and yeasts and molds). Aerobic plate counts were < 2.5 log CFU/g for olive samples washed in chlorine dioxide at all NaCl concentrations. At 4°C, the population of yeasts and molds increased steadily during the shelf life in Gemlik olive samples washed with all of the solutions, except chlorine dioxide, whereas yeast and mold counts in Edincik olives decreased depending on the increase in salt concentration. Therefore, different combinations of organic acids, NaCl, and vacuum packaging can be successfully used to control the growth of yeasts and molds in these olives. The combination of vacuum sealing (with a 10-ppm chlorine dioxide wash) and storage at 4°C was the most effective approach for controlling the growth of lactic acid bacteria and yeasts and molds. Members of the sensory panel considered saltiness to be appropriate at 2.5 and 5.0% NaCl. Softness and bitterness scores increased with reduced NaCl concentrations, but rancidity and hardness scores increased as NaCl concentration increased.
Citation - WoS: 30
Citation - Scopus: 40
Effect of Various Process Parameters on Morphology, Rheology, and Polygalacturonase Production by Aspergillus Sojae in a Batch Bioreactor
(American Institute of Chemical Engineers, 2007-07) Öncü, Şelale; Tarı, Canan; Tarı, Canan; Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The 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.
Citation - WoS: 2
Citation - Scopus: 2
Effects of Golden Thistle (scolymus Hispanicus L.) on Cytotoxic Activity: Cell Cycle Arrest and Apoptotic Properties on the Caco-2 Cell Line
(Mary Ann Liebert Inc., 2022-05) Özel Taşcı, Cansu; Güleç, Şükrü; Güleç, Şükrü; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Cancer is a global concern for many individuals with high mortality rates, with colon cancer being the third most common diagnosed cancer worldwide. A phytochemical-rich diet is often recommended in the prevention and during the treatment of cancer cases. Golden thistle (GT) plant (Scolymus hispanicus L.) is a wild edible plant widely consumed in the Mediterranean countries. In this study, we aimed to obtain a hydromethanolic extract from three parts of the GT plant and test its antiproliferative activity in the CaCo-2 human adenocarcinoma cell line. Concentrations of the golden thistle extract (GTE) were used to treat CaCo-2 cells and the most significant reduction was detected with 4 mg/mL GTE after 72 h, with 78.3% decrease in cell viability (P < .05). Additionally, 4 mg/mL GTE caused 7.8-fold higher release of lactate dehydrogenase enzyme, indicating cell death after treatment. Flow cytometric analyses concluded both 3.3-fold higher early and late apoptotic activity of the 4 mg/mL GTE compared with the nontreated control group (P < .05). Last, 4 mg/mL GTE showed 24.1% reduction in the G1 phase and 38.1% increase in the S phase of cell cycle distribution. The alteration of G1 and S phases in the cell cycle led to growth reduction of CaCo-2 cells and caused apoptosis. Copyright
Citation - WoS: 47
Citation - Scopus: 54
Effects of Nisin and Lysozyme on Growth Inhibition and Biofilm Formation Capacity of Staphylococcus Aureus Strains Isolated From Raw Milk and Cheese Samples
(International Association for Food Protection, 2012-09) Sudağıdan, Mert; Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Effects of nisin and lysozyme on growth inhibition and biofilm formation capacity of 25 Staphylococcus aureus strains isolated from raw milk (13 strains) and cheese (12 strains) were studied. Nisin was tested at concentrations between 0.5 and 25 μg/ ml; the growth of all strains was inhibited at 25 μg/ml, but the resistances of strains showed a great variation at lower nisin concentrations. In contrast, lysozyme tested at concentrations up to 5.0 mg/ml showed no inhibition on the growth of strains. Nisin used at the growth inhibitory concentration prevented the biofilm formation of strains, but strains continued biofilm formation at subinhibitory nisin concentrations. Lysozyme did not affect the biofilm formation of 19 of the strains, but it caused a considerable activation in the biofilm formation capacity of six strains. Twelve of the strains contained both biofilm-related protease genes (sspA, sspB, and aur) and active proteases; eight of these strains were nisin resistant. These results suggest a potential risk of S. aureus growth and biofilm formation when lysozyme is used in the biopreservation of dairy products. Nisin can be used to control growth and biofilm formation of foodborne S. aureus, unless resistance against this biopreservative develops. Copyright ©, International Association for Food Protection.
Citation - WoS: 11
Citation - Scopus: 13
Effects of Processing Parameters on Chemical and Physical Properties of Enzymatically Interesterified Beef Tallow-Corn Oil Blends
(John Wiley and Sons Inc., 2020) Aktaş, Ayşe Burcu; Özen, Fatma Banu; Özen, Banu; Alamprese, Cristina A.; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The purpose of this study was to improve some physical and chemical characteristics of tallow through enzymatic interesterification process with corn oil and to investigate effects of process parameters on chemical and physical properties of obtained products. Full factorial design was constructed using blend ratio and reaction time as process parameters. Enzymatic interesterification was catalyzed with sn-1,3-specific lipase. Interesterified lipids have higher free fatty acid content and lower oxidative stability compared to initial blends. Interesterification did not cause trans-fatty acid formation and products mostly contained beta crystals. Solid fat content and slip melting point decreased up to 6 hr of interesterification; however, longer reaction times have negative effects on these parameters. Statistical analyses' results confirmed that reaction time is highly important for enzymatic interesterification. Practical applications Some of interesterified lipids can be utilized as alternatives to margarines or butterfat due to their lower trans-fatty acid content and crystal morphology.
Citation - WoS: 3
Citation - Scopus: 4
Evaluation of Agro-Industrial Wastes, Their State, and Mixing Ratio for Maximum Polygalacturonase and Biomass Production in Submerged Fermentation
(Taylor and Francis Ltd., 2015-10) Göğüş, Nihan; Evcan, Ezgi; Evcan, Ezgi; Tarı, Canan; Tarı, Canan; Cavalitto, Sebastian F.; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
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.
Citation - WoS: 3
Citation - Scopus: 3
Evaluation of High Hydrostatic Pressure Effects on Bovine Red Blood Cells and Platelets
(Taylor and Francis Ltd., 2009-06) Ceylan, Çağatay; Ceylan, Çağatay; Severcan, Mete; Bozoğlu, Faruk; Severcan, Feride; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The objective of this study was to investigate the effects of high hydrostatic pressure (HHP) on the stability of red blood cells (RBCs) and platelets. Bovine blood cells (n=5) were treated with the pressure of 55, 110, 154 and 220MPa at 25°C for 5min. Light microscopy, atomic force microscopy and flow cytometry studies revealed that RBCs were morphologically stable up until the 220MPa pressure treatments, at which surface modifications were observed. The platelets were found to be less stable than RBCs. HHP application did not cause any significant change in the signal intensity, band area and frequency values of the infrared bands with the exception that a significant variation was observed in the area of the cholesterol band. No statistically significant variations were observed in the secondary structure elements due to HHP treatment according to the artificial neural network study based on the FTIR data.
Citation - WoS: 13
Citation - Scopus: 14
Evaluation 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; Hakgüder Taze, Bengi; Tarı, Canan; Demir, Hande; Ünlütürk, Sevcan; Tarı, Canan; Ünlütürk, Sevcan; Lahore, Marcelo Fernandez; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of Engineering
Orange 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.
Citation - WoS: 32
Citation - Scopus: 32
Exploitation of Agricultural Wastes and By-Products for Production of Aureobasidium Pullulans Y-2311 Xylanase: Screening, Bioprocess Optimization and Scale Up
(Springer Verlag, 2017-04) Yeğin, Sırma; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; Sargın, Sayıt; Göksungur, Yekta; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The potential of several agricultural wastes and by-products (wheat bran, oat bran, corn cob, brewer’s spent grain, malt sprout, artichoke stem, sugar beet pulp, olive seed, cotton stalk and hazelnut skin) was examined as the substrate for xylanase production by Aureobasidium pullulans Y-2311-1. Based on the screening studies, wheat bran was selected as the best substrate for further optimization studies. The effects of initial medium pH, temperature and incubation time on xylanase production in shake flask system were optimized by response surface methodology (RSM). The optimum levels of the process variables defined by the model (initial medium pH, 4.24; temperature, 30.27 °C; and incubation time 126.67 h) resulted in production of 85.19 U/ml xylanase. Taking the RSM optimized parameters in shake-flask scale into consideration; xylanase production was scaled up to bioreactor system with a working volume of 1.5 l. The peak of enzyme production was achieved after 126 h incubation that has previously been determined by RSM studies at shake flask level. Furthermore, the optimum levels of agitation and aeration in bioreactor system was found as 200 rpm and 1.5 vvm. Maximum enzyme production was close to 85 kU/l which could be translated into a productivity of 0.68 kU/l/h. No previous work considered the statistical optimization of xylanase production by A. pullulans on wheat bran and scale up of the bioprocess to a bioreactor system

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