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https://hdl.handle.net/20.500.12491/146

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High-pressure processing of traditional hardaliye drink: Effect on quality and shelf-life extension
(MDPI, 2023) Atmaca, Bahar; Demiray, Merve; Evrendilek, Gülsün Akdemir; Bulut, Nurullah; Uzuner, Sibel
Hardaliye, as one of the oldest and lesser known traditional beverages, is produced using red grape pomace from wine production. This drink production is achieved through lactic acid fermentation, with the addition of sour cherry leaves and mustard seeds-either heat-treated, grinded, or whole-in various concentrations. Hardaliye has a very short shelf life; thus, efforts have recently been made to process hardaliye with novel processing technologies in order to achieve shelf-life extension. Therefore, the high-hydrostatic-pressure (HHP) processing of hardaliye was performed to determine its impact on important properties, including in microbial inactivation and shelf-life extension, with respect to a Box-Behnken experimental design. Maximum log reductions of 5.38 & PLUSMN; 0.6, 5.10 & PLUSMN; 0.0, 5.05 & PLUSMN; 0.2, and 4.21 & PLUSMN; 0.0 with HHP were obtained for Brettanomyces bruxellensis, total mesophilic aerobic bacteria, Lactobacillus brevis, and total mold and yeast, respectively. The processing parameters of 490 MPa and 29 & DEG;C for 15 min were found as the optimal conditions, with the response variables of an optical density at 520 nm and the inactivation of L. brevis. The samples processed at the optimal conditions were stored at both 4 and 22 & DEG;C for 228 d. While the non-treated control samples at 4 and 22 & DEG;C were spoiled at 15 and 3 d, the HHP-treated samples were spoiled after 228 and 108 d at 4 and 22 & DEG;C, respectively.
Fatty acids and tocopherols of Turkish Salvia fruticose, Salvia tomentosa, Stachys aleurites and Stachys cretica subsp. Anatolica seed oils
(Innovhub Stazione Sperimentale per le Industrie, 2018) Özkan, Gülcan; Göktürk, Ramazan Süleyman; Kıralan, Mustafa; Ramadan, Mohamed Fawzy
Salvia fruticosa, Salvia tomentosa, Stachys aleurites, and Stachys cretica subsp. anatolica species are members of the Lamiaceae family. Oil content, fatty acids, and the tocopherol composition of seed oils from these species were studied. The seed oil yield varied from 12.2% (Salvia fruticosa) to 17.2% (Stachys aleurites). Linoleic acid was found in high levels in the range from 44.13% (Stachys aleurites) to 61.7% (Salvia tomentosa), followed by oleic acid in the range from 23.1% (Salvia tomentosa) to 34.2% (Stachys aleurites). ?-Tocopherol was the most abundant tocopherol in the oils. Salvia tomentosa seed oil had the highest amount of ?-tocopherol (834.9 mg/kg), wherein the lowest amount was found in Stachys cretica seed oil (327.1 mg/kg). The work showed that the seed oils under study are rich sources of unsaturated fatty acids and ?-tocopherol that may contribute to human health.
Enhanced reducing sugar production and extraction for Chlorella vulgaris in mixotrophic cultivation using high hydrostatic pressure processing and ultrasound
(Taylor & Francis Ltd, 2024) Uzuner, Sibel; Kurhan, Şebnem; Evrendilek, Gülsün Akdemir
Although extraction of polysaccharides to convert reducing sugars (RS) from microalgae by acid or alkali pretreatments and enzymatic hydrolysis has been extensively studied, few reports exploring the use of high hydrostatic pressure processing (HHP) and ultrasonication (US) as emerging technologies for the extraction of sugars from microalgae biomass exist. Thus, the present study was conducted to determine the effects of mixotrophic growth and stress conditions (NaNO3 and CO2 concentration and light intensity) on RS and protein accumulation in the unicellular green alga Chlorella vulgaris in addition to optimization of the effectiveness of the sequential applications of HHP and US with dilute acid as well as simultaneous enzymatic saccharification on the production of RS from microalga cells. High light intensity, high CO2 concentration and limited nitrogen concentration promoted RS production. The maximum protein content (0.0683 mg g(-1)) was achieved at 0.3 g l(-1) NaNO3 concentration, 7000 mu mol photons m(-2) s(-1) and 6 l min(-1) CO2 concentration. The highest RS content of C. vulgaris after 48 h enzymatic saccharification (583.86 +/- 13.23 mg g(-1)) was obtained at 1% (w/w) acid concentration and 80% amplitude for 30 min with 79.4% RS yield. Combined US-assisted dilute acid pretreatment and enzymatic hydrolysis were also found to be more effective than HHP assisted dilute acid pretreatment and enzymatic saccharification. Therefore, microalgal biomass can be considered a suitable renewable feedstock used in fermentation. Highlights center dot The cultivation period of Chlorella vulgaris was reduced from 25 days to 14 days using mixotrophic growing conditions.center dot Mixotrophic conditions enhanced reducing sugar productivity.center dot Novel extraction techniques enhanced the extraction of reducing sugar from microalgae.
Processing and preservation of apple juice by pulsed electric fields combined with cinnamon essential oils: Exploring the effect of synergism
(Wiley, 2023) Evrendilek, Gülsün Akdemir; Turgut, Bengi Karaoğuz
Apple juice samples were treated by pulsed electric field (PEF) alone and in combination with cinnamon essential oils (CEO) at 0.0005, 0.003, and 0.06 & mu;L mL-1 concentrations as a function of treatment time. Results revealed 11 different compounds with the highest concentrations of 44.79% 3-propenal 3-phenyl, 34.98% trans-cinnamaldehyde, and 10.18% 4-propenal 3-phenyl in CEO. pH and total soluble solids of the apple juice samples significantly decreased; whereas total phenolic substance content of the samples significantly increased by added CEO. The same process parameters caused 3.26 & PLUSMN; 0.19 and 3.83 & PLUSMN; 0.16 log reductions on TAMB and TMY, revealing no detectable numbers after PEF treatment. Similarly, maximum 5.13 and 3.87 log reductions on Escherichia coli O157:H7 and Listeria monocytogenes were obtained on 0.06 & mu;L mL-1 CEO added samples treated after 604 & mu;s. Moreover, increased CEO concentration, when treatment time was constant, caused significantly more microbial inactivation. Increase in treatment time resulted in an incline on & UDelta;H of the samples. Response optimization revealed that 604 & mu;s treatment time and 0.06 & mu;L mL-1 concentration were the optimal treatment parameters with 0.63 composite desirability. Processing of apple juice supplemented with cinnamon essential oils in three different concentrations and processed by pulsed electric field by increased treatment time provided inactivation of endogenous and pathogenic bacteria without adversely affecting the physical, and bioactive properties with an increase in & UDelta;H in thermal properties.image
Optimization and characterization of biodegradable films from chicken gelatin crosslinked with oxidized phenolic compounds
(Elsevier, 2024) Erge, Aydın; Güler, Büşra Zeynep; Eren, Ömer
Chicken gelatin derived from poultry by-product was combined with caffeic acid (CA), rutin (RUT) and glycerol (GLY) to obtain biodegradable films. Optimum cross-linking conditions were investigated using Response Surface Methodology (RSM). The results showed that cross-linking led to lower L* value and higher b*, and the higher opacity values in the films. Water solubility (WS) decreased up to 50% after the incorporation of 1.25% CA compared to the commercial gelatin (cattle and pig based) films. Crosslinking improved the thermal stability and the tensile strength (TS) of films. Optimized cross-linking combination was determined as 0.96-1.56% CA, 0-1.25% RUT, and 29.5-30.5% GLY. Overall, this study demonstrated that crosslinking by CA and RUT can be used to improve the physical and barrier properties of gelatin films having excellent potential for the development of biodegradable films for packaging uses. These films may also result in an improvement and added value in poultry by-products.
Examination of pairing mechanism, orbital hybridization, stabilization and magnetization behavior of Tb/Y and Zn/Cu partially substituted Y-123 Superconductors
(Elseiver Science SA, 2022) Öztürk, Özgür; Güdücü, G.; Safran, Serap; Yıldırım, Gürcan
The effect of homovalent Tb/Y and Zn/Cu substitution on electrical, superconducting, structural, and magnetic features of Y-123 ceramic materials is extensively examined by powder X-ray diffraction, electrical resistivity, scanning electron microscopy, energy dispersive X-ray spectrometry, DC magnetization VSM measurements and related calculations. Y1-xTbxBa2Cu3O7-? and YBa2(Cu(1-x)Znx)(3)O(7-? )samples are prepared with four different molar percentages (0.0 <= x <= 0.15) using the sol-gel technique. DC magnetization data and the Bean model are used to evaluate change in critical current densities with an applied magnetic field. Energy-dispersive X-ray spectrometry measurements indicate that materials are exactly produced in the desired stoichiometric ratios. Moreover, all the experimental findings show that the fundamental characteristic properties are observed to decrease with replacement mechanism. The degradation mechanism with partial substitution is thoroughly explained scientifically in the basic contents for the first time. The role of Tb/Y and Zn/Cu partial substitution on the oxygen concentration level in unit cell, ordering degree in the Cu-O ribbons, lattice cell parameters, grain size, and the number of holes in the sigma antibonding in-plane Cu-O bonds are also discussed in detail. Additionally, beginning of weak-interaction problems between adjacent superconductive layers, formation of microscopic structural faults and decoupling of super-conducting grains are noted to be the negative effect of substitution mechanism. Regardless, it is observed that Tb-doped samples possessing more uniform surface morphologies with better surface texture and connection quality between particles show much higher magnetization behavior and superconducting properties. All in all, this study developing a scientific methodology about why fundamental characteristic features change with the partial replacements of Tb/Y and Zn/Cu in crystal systems seems a pioneering investigation to construct novel and feasible application fields for the Y-123 ceramic compounds. (C) 2022 Elsevier B.V. All rights reserved.
Assessing edible composite film polymer from potato industry effluent under high hydrostatic pressure and its antimicrobial properties
(Wiley, 2022) Evrendilek, Gülsün Akdemir; Bulut, Nurullah; Uzuner, Sibel
Development of edible film from potato industry effluent having antimicrobial properties against Salmonella enteritidis and Escherichia coli O157:H7 by addition of Citrus sinensis volatile oil (VO), and changes of its textural properties under high hydrostatic pressure (HHP) are investigated. The optimum operational conditions are determined as 500 MPa pressure, 36.97 mu L VO, and 15 min processing time with the minimum force value of 372.33 x g. Textural properties are also modeled through empirical modeling, best fit Box-Behnken design, and artificial neuron network. Inhibition zones for Salmonella enteritidis and E. coli O157:H7 at the optimum HHP conditions are 1.50 +/- 0.11 and 2.18 +/- 0.07 cm, respectively. Textural properties of force and elongation at break of the HHP-processed films range from 2.27 +/- 0.52 to 5.23 +/- 0.38 N, and from 8.57 +/- 1.31 to 13.36 +/- 1.36 mm, respectively. Thermal transition of the edible film is observed at 87.42 degrees C for 7.36 min. Addition of C. sinensis VO improves the antimicrobial properties, whereas HHP improves the textural properties of the film. It is suggested that the developed film has potential to be used as an edible food packaging material.
Prediction of Aspergillus parasiticus inhibition and aflatoxin mitigation in red pepper flakes treated by pulsed electric field treatment using machine learning and neural networks
(Elseiver, 2022) Evrendilek, Gülsün Akdemir; Bulut, Nurullah; Atmaca, Bahar; Uzuner, Sibel
Presence of aflatoxins in agricultural products is a worldwide problem. Because of their high heat stability and resistance to most of the food processing technologies, aflatoxin degradation is still a big challenge. Thus, effi-cacy of pulsed electric fields (PEF) by energies ranging from 0.97 to 17.28 J was tested to determine changes in quality properties in red pepper flakes, mitigation of aflatoxins, inactivation of aflatoxin producing Aspergillus parasiticus, reduction in aflatoxin mutagenity, and modelling of A. parasiticus inactivation in addition to aflatoxin mitigation. Maximum inactivation rate of 64.37 % with 17.28 J was encountered on the mean initial A. parasiticus count. A 99.88, 99.47, 97.75, and 99.58 % reductions were obtained on the mean initial AfG1, AfG2, AfB1, and AfB2 concentrations. PEF treated samples by 0.97, 1.36, 5.76, and 17.28 J at 1 mu g/plate, 0.97, 1.92, 7.78, 10.80 J at 10 mu g/plate, and 0.97, 1.92, 2.92, 4.08, 5.76, 4.86, 6.80, 9.60, 10.80, and 10.89 J at 100 mu g/plate were not mutagenic. Modelling with gradient boosting regression tree (GBRT), random forest regression (RFR), and artificial neural network (ANN) provided the lowest RMSE and highest R2 value for GBRT model for the predicted inactivation of A. parasiticus, whereas ANN model provided the lowest RMSE and highest R2 for predicted mitigation of AfG1, AfB1, and AfB2. PEF treatment possess a viable alternative for aflatoxin degradation with reduced mutagenity and without adverse effect on quality properties of red pepper flakes.
High hydrostatic processing of marinated ground chicken breast: Exploring the effectiveness on physicochemical, textural and sensory properties and microbial inactivation
(Elsevier Sci LTD, 2022) Evrendilek, Gülsün Akdemir
High hydrostatic pressure (HHP) processing of marinated ground chicken breast meat samples by 200-600 MPa for 5-15 min at ambient temperature revealed that increased magnitude of pressure and treatment time provided significant increase in pH, surface L*, a*, b*, and total color difference (delta E), inner a*, b* and delta E color values, marinade uptake, total antioxidant capacity, total phenolic substance content, textural properties of cooking loss, hardness, chewiness, cohesiveness, and gumminess, and sensory properties of appearance and color. A significant decrease was observed in the inner color L* value, and textural properties of springiness, whereas no significant changes were detected on sensory properties of aroma, hardness, and aftertaste. HHP processing at 600MPa/15 min provided maximum 4.73 and 3.89 log inactivations on the initial total mesophilic aerobic bacteria and total mold and yeast counts. The initial Salmonellae and total coliform counts of 3.53 +/- 0.12 and 6.59 +/- 0.11 log cfu/g were reduced to undetectable level by 400 MPa/15 min and 600 MPa for 5, 10, and 15 min, respectively. The results reveled that HHP is very efficient for diffusion of marinade solution with providing microbial safety without adversely affecting physical, textural and sensory properties of marinated ground chicken breast samples.
Exploring the lentil protein and onion skin phenolics interaction by fluorescence quenching method
(Elseiver, 2022) Köroğlu, Deniz Günal; YIlmaz, Hilal; Turan, Semra; Çapanoğlu, Esra
In this paper, the effect of two phenolic extracts (red and yellow onion skin, RS and YS respectively) with different phenolic profiles on the fluorescence quenching of lentil protein isolate (LPI) was investigated. The quenching effect of YS at 4-30 mu M concentrations on lentil proteins was in the range of 20.9-77.8%. A linear Stern-Volmer plot was obtained in agreement with static quenching for the LPI-YS complex while giving the blue shift at maximum emission between 8 and 30 mu M YS concentrations. Thermodynamic parameters of the LPI-YS complex showed that the interaction was hydrophobic (Delta H>0 and Delta S>0), enthalpy driven (Delta H>Delta S), and nonspontaneous (Delta G>0) reaction. RS provided a more effective quenching effect at lower concentrations compared to YS and the quenching effect of RS at 1-16 mu M concentrations was 24.5-92.8%. On the other hand, the red shift was observed between 0 and 16 mu M RS concentrations, where the Stern-Volmer plot was non-linear, so there was a sphere of action model for LPI-RS complexes.
Monitoring, control and reduction of bioaerosols in the intensive care unit in Turkey
(Ice Publishing, 2022) Lakestani, Sanaz; Çakır, İbrahim; Gözdaş, Hasan Tahsin; Yıldız, İsa; Demirhan, Abdullah
Maintaining high indoor air quality in hospitals is important for protecting the health of both personnel and patients. In this study, the results of air quality monitoring carried out in the intensive care unit of a hospital in Bolu, Turkey, are discussed. Air disinfection devices were used to reduce the concentrations of bacteria. A 4-week sampling programme was implemented. In the first and the last weeks of the sampling, the disinfection devices were turned off, while in the second and third weeks, they were turned on. Bioaerosols were collected, and their indoor levels were determined by counting all plate colonies and bacterial types were identified by matrix-assisted laser desorption/ionisation-time of flight mass spectrometry. The highest levels of bacteria were measured in the mornings and before the air disinfection devices were turned on. Doctors did their rounds at approximately nine to ten o'clock. The dominant bacteria in the air samples examined were Staphylococcus hominis, Micrococcus luteus, Staphylococcus capitis, Staphylococcus epidermidis, Corynebacterium afermentans and Staphylococcus haemolyticus. The results showed that the air disinfection devices were effective in decreasing the concentration of microorganisms between 83.4 and 55% in the intensive care unit, which is very important for the healthcare staff and patients, particularly during pandemics.
Start Codon Targeted (SCoT) markers for the assessment of genetic diversity in yeast isolated from Turkish sourdough
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2022) Aydın, Furkan; Özer, Göksel; Alkan, Mehtap; Çakır, İbrahim
Molecular markers are valuable tools for assessing the genetic variation in yeast. Here, we investigated the utility of SCoT markers for the genetic characterization of yeast strains at inter and intraspecies levels. A total of 345 endogenous yeast strains were isolated from 65 Type I sourdough samples collected from six different regions of Turkey. The seven SCoT primers produced 221 bands, of which 95.47% were polymorphic. Each primer could successfully differentiate species, supported by PIC and RP values. The ITS sequencing of isolates selected from the UPGMA dendrogram revealed that Saccharomyces cerevisiae predominated the microflora, followed by Kazachstania servazzii, K. humilis, Wickerhamomyces anomalus, Torulaspora delbrueckii, and Pichia kudriavzevii, respectively. The AMOVA revealed a high genetic variation between (49%) and within populations (51%) for S. cerevisiae. The high gene flow observed among S. cerevisiae populations suggests that it may have contributed to the geographical evolution of S. cerevisiae via the transportation of the sourdough samples. The different geographical origins were most likely to group separately on the UPGMA and PCoA. Saccharomyces cerevisiae strains from more distant populations generally displayed more significant genetic variation. SCoT markers can successfully be used alone or with the other existing DNA markers for DNA fingerprinting and analyzing the genetic variation between and within species.
Optimization of leavened dough frying conditions using the response surface methodology
(INNOVHUB SSI-AREA SSOG, 2023) Turan, Semra; Keskin, Şule; Solak, Rukiye
In this study, the optimum frying conditions of leavened doughs to minimise the oxidation products were investigated. Fifty repeated deep frying of leavened doughs with 0-2% salt content was performed for 1-5 min at 160-200?. While K232, K270, p-anisidine and polymer triglycerides contents of fried dough oil (FDO) were noteworthy (p < 0.05) affected by the frying temperature and the frying time, the dough salt content did not affect these values significantly (p > 0.05). The combined effects of frying temperature and time on K270, p-anisidine and polymer triglycerides contents were significant (p < 0.05). The effects of interaction of frying temperature and dough salt content on p-anisidine value were found to be significant (p < 0.05). The optimum frying conditions to minimize the K232, K270, p-anisidine values and polymer triglyceride content of FDO were observed where the frying time was 1 minute, the frying temperature was 160? and the salt content was 2%.
Molecular and technological characterization of Saccharomyces cerevisiae from sourdough
(MDPI, 2023) Aydın, Furkan; Günen, Tacettin Utku; Kahve, Halil İbrahim; Güler, Emrah; Özer, Göksel; Aktepe, Yeşim; Çakır, İbrahim
DNA markers help detect the intraspecific genetic diversity of yeast strains. Eight ISSR (Inter Simple Sequence Repeats) primers were used to assess the intraspecific diversity of Saccharomyces cerevisiae (n = 96) from different populations (n = 3), evaluate the technological characteristics, and investigate trait-loci associations. The primers amplified 154 reproducible and scorable bands, of which 79.87% were polymorphic. The UPGMA (unweighted pair group method with arithmetic mean) dendrogram clustered 96 isolates into two main clusters, supported by STRUCTURE HARVESTER results (Delta K = 2). Analysis of molecular variance (AMOVA) indicated significant genetic differences between (15%) and within the populations (85%) (p < 0.001). Twenty-nine genetically distinct strains were selected for the technological characterization. Principal component analysis (PCA) revealed that five strains with high fermentation capacity, leavening activity, high growth index at 37 degrees C, and harsh growth conditions were technologically relevant. Trait-loci association analyses indicated that the highest correlation (r = 0.60) was recorded for the fermentation capacity on the 8th and 113th loci, amplified by ISSR-1 and ISSR-6 primers, respectively (p < 0.05). The strains yielding high performances and the associated loci amplified by ISSR markers possess a high potential to generate locus-specific primers to target the strains with high fermentation capacity.
Recent developments in antimicrobial surface coatings: Various deposition techniques with nanosized particles, their application and environmental concerns
(Elsevier Science London, 2023) Kışla, Duygu; Gökmen, Gökhan Gurur; Evrendilek, Gülsün Akdemir; Akan, Tamer; Vlcko, Tomas; Kulawik, Piotr
Background: The recent development of nanotechnology has given rise to many potent applications, including control and eradication of pathogenic microorganisms. The most promising of those methods seems to be the development of surface coatings containing various nanoparticles and exhibiting antimicrobial properties. This method allows to reduce or even eliminate the possible microbiological threat without the need for continuous surface disinfection, thermal treatment or the use of various novel, non-thermal treatments. Scope and approach: In this review, deposition techniques, mechanisms of actions for different nanoparticles, as well as potential applications and environmental concerns are described. Key findings and conclusions: Nine deposition techniques have been identified with regard to novel antimicrobial coatings containing nanoparticles, including techniques of thermal evaporation, vacuum arc, pulsed laser deposition, sol-gel, chemical vapor deposition, sputtering, thermal as well as electro spray and electrochemical deposition. Besides, mechanisms of antimicrobial action are described considering various nanoparticles, i.e. the well-established antibacterial mechanism of most commonly used nanoparticles, the current state of knowledge related to their antifungal properties and the antiviral mechanism of Ag nanoparticles. Moreover, the review identified the potential industry fields in which such coatings can be applied, including food packaging, food contact surfaces, water treatment, biomedical applications and the textile industry. Finally, current knowledge gaps and fields for future research are identified, which include establishing antiviral mechanisms of action and effectiveness of various nanoparticles. Various environmental research regarding the accumulation of nano -particles in the environment, with their uptake as well as effect on growth and development of plants and animal is also needed.
The effect of in vitro digestion on matcha tea (camellia sinensis) active components and antioxidant activity
(MDPI, 2022) Kolackova, Tereza; Sumczynski, Daniela; Minarik, Antonin; Yalçın, Erkan; Orsavova, Jana
This study investigates the effects of in vitro digestion on the antioxidant activity and release of phenolics, xanthine alkaloids, and L-theanine contents of matcha. It establishes digestibility values between 61.2-65.8%. Considering native matcha, the rutin content (303-479 mu g/g) reached higher values than catechin (10.2-23.1 mu g/g). Chlorogenic acid (2090-2460 mu g/g) was determined as predominant. Rutin, quercetin, ferulic, ellagic, and caffeic acid were the least-released phenolics, and their remaining residues reached 76-84%. Protocatechuic, hydroxybenzoic acid, epigallocatechin, and epigallocatechin-3-gallate were the best-released phenolics, with the remaining residues under 1%. Caffeine, L-theanine, and theobromine contents in native matcha reached 16.1, 9.85, and 0.27 mg/g, respectively. Only caffeine (3.66-5.26 mg/g) and L-theanine (0.09-0.15 mg/g) were monitored in the undigested residue, representing 13 and 0.1% of the remaining part, respectively. A chemiluminescence assay showed that water-soluble antioxidants showed significant antioxidant activity in native matcha, while lipid-soluble compounds showed higher antioxidant activity in the undigested samples. Cinnamic and neochlorogenic acids were determined as the main contributors to the ACW values in the undigested matcha, epicatechin, and quercetin in the ACL fraction. The application of the digestion process reduced the antioxidant activity by more than 94%. SEM has proved specific digestion patterns of in vitro digestibility of matcha.
Isolation and characterization of yogurt starter cultures from traditional yogurts and growth kinetics of selected cultures under lab-scale fermentation
(Taylor & Francis Inc, 2023) Çakmakoğlu, Selma Kayacan; Vurmaz, Melike; Bezirci, Emine; Kaya, Yasemin; Dikmen, Hilal; Encu, Betül; Soykut, Esra Acar; Çakır, İbrahim
The development of new starter cultures is a crucial task for the food industry to meet technological requirements and traditional products are important reservoirs for new starter cultures. In this respect, this study aimed to isolate, identify, and determine the technological characteristics of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains originated from traditional yogurt samples. Genotypic discrimination of 200 isolates revealed the presence of distinct 19 S. thermophilus and 11 Lb. delbrueckii subsp. bulgaricus strains as potential starter cultures. Strain-specific properties determined the acidification capacity of the yogurt starter cultures and a higher acidification capacity was observed for S. thermophilus strains compared to Lb. delbrueckii subsp. bulgaricus strains. Proteolytic activity was found between 0.012-0.172 and 0.078-0.406 for S. thermophilus and Lb. delbrueckii subsp. bulgaricus strains, respectively. 4 of S. thermophilus and 3 of Lb. delbrueckii subsp. bulgaricus strains were found resistant to all tested bacteriophages. The antibiotic susceptibility tests of the isolates revealed that a very low antibiotic resistance was observed for the yogurt starter cultures. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected S. thermophilus and Lb. delbrueckii subsp. bulgaricus was calculated as 0.527 h(-1) and 0.589 h(-1), respectively.
Ozone processing of corn grains: Effect on seed vigor and surface disinfection
(TAYLOR & FRANCIS INC, 2023) Evrendilek, Gülsün Akdemir
Ozone treatment of corn seeds with respect to determination on changes in germination ability, germination under salt stress, seedling growth, seedling root length, conductivity and inactivation of endogenous microflora was studied. Corn seeds immersed in water treated by fixed ozone dose of 12.5 g/m(3) for 1 (1O(3)), 3 (2O(3)) and 5 min (3O(3)) at room temperature. Ozone treatment provided full germination (100%) of the corn seeds on the 2(nd) day; whereas 66.6% of the control seeds germinated on the 8(th) days after planting. Ozone treated seedling were significantly taller and stronger than the control samples with significantly longer seedling root. Germination under 100 mM salt stress for ozone treated seeds was significantly higher than that of the control samples. Electrical conductivity of the seeds was significantly affected by the measurement time rather than ozone treatments. Ozone treatments provided significant inactivation on total aerobic mesophilic bacteria and total mold and yeast of the endogenous bacteria revealing maximum of 5.31 and 6.15 log reductions, respectively. It was concluded that ozone treatment at 12.5 g/m(3) for 5 min can be utilized to treat corn seeds as these treatment parameters provided maximum inactivation on endogenous microflora with improvement of vigor and stronger seedling formation.
Pulsed electric field processing of red wine: Effect on wine quality and microbial inactivation
(MDPI, 2022) Evrendilek, Gülsün Akdemir
Pulsed electric field (PEF) treatment of red wine samples with energies changing from 2.4 to 13.2 kJ to inactivate Saccharomyces cerevisiae, Hansenula anomala, Candida lipolytica, Lactobacillus delbrueckii ssp. bulgaricus, and Escherichia coli O157:H7 with the determination of the changes in the quality and sensory properties in addition to metal ion concentration (Na, Mg, K, and Mn) were explored. Increased applied energy resulted in a significant increase in pH, conductivity, lightness (L*), yellowness (b*), and total phenolic substance content with significant inactivation of all microorganisms with no significant change in metal ion concentration. Sensory properties of particle status, sour taste, and aftertaste were significantly decreased, whereas the other measured properties were significantly increased by 13.2 kJ PEF treatment (p < 0.05). Joint optimization studies for the most optimal processing parameters for the measured properties were 488 s, 0.13 kJ, and 0.22 kV; 488 s, 13.2 kJ, and 31 kV; 348 s, 9.39 kJ, and 31 kV/cm; and 488 s, 13.2 kJ, and 0 kV EFS, with 0.79, 0.69, 1.00, and 0.72 composite desirability, respectively.
Genetic diversity and population structure of Saccharomyces cerevisiae isolated from Turkish sourdough by iPBS-retrotransposons markers
(Springer, 2022) Aydın, Furkan; Özer, Göksel; Alkan, Mehtap; Çakır, İbrahim
Molecular DNA markers are valuable tools for analyzing genetic variation among yeast from different populations to reveal the genetically different autochthonous strains. In this study, we employed inter-primer binding site (iPBS) retrotransposon polymorphism to assess the genetic variation and population structure of 96 Saccharomyces cerevisiae isolates from four different regions in Turkey. The nine selected iPBS primers amplified 102 reproducible and scorable bands, of which 95.10% were polymorphic with an average of 10.78 polymorphic fragments per primer. The average polymorphism information content and the resolving power were 0.26-3.58, respectively. Analysis of molecular variance (AMOVA) revealed significant (P < 0.001) genetic differences within populations (88%) and between populations (12%). The unweighted pair group mean with arithmetic (UPGMA) dendrogram grouped 96 S. cerevisiae strains into two main clusters, where the highest probability of the data elucidating the population structure was obtained at Delta K = 2. There was not an obvious genetic discrimination of the populations according to geographical regions on UPGMA, supported by principal coordinate analysis. However, the individuals of the closer provinces in each population were more likely to group together or closely. The results indicate that iPBS polymorphism is a useful tool to reveal the genetically diverse autochthonous S. cerevisiae strains that may be important for the production of sourdough or baked goods.

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