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    Bioactivity, DNA damage protecting, and aroma potential of oleuropein enriched olive leaf extract by optimization of ultrasound-assisted process
    (Wiley, 2024) Ilgaz, Ceren; Kelebek, Haşim; Kadiroglu, Pinar
    In this study, Box-Behnken experimental design was employed to optimize Ultrasound-assisted extraction (UAE) method to obtain oleuropein-rich extract from olive leaf. The effect of three parameters, ethanol concentration (30%-70%), amplitude (30%-50%), and ultrasonication time (5-15 min) on oleuropein content were evaluated through experimental design. The total phenolic content, antioxidant capacity, DNA damage scavenging activity, aroma profile, and antimicrobial activity of olive leaf were also investigated. The optimum extraction condition was determined as 30% amplitude, 70% ethanol, and 5 min extraction time. The amount of oleuropein was found to be 42.621 mg/g dry leaves at the optimum condition. The total phenolic content of the optimized extract was found as 45.13 mg GAE/g dry leaves while the antioxidant capacity of the optimized extract was 216 mu mol Trolox/g in DPPH and 213.19 mu mol Trolox/g in ABTS method. Twenty-three volatile compounds were identified in extracts, mainly aldehydes and alcohols. The extracts showed high antimicrobial activity against selected bacterial strains. DNA damage protecting activity of extracts on plasmid DNA was clearly demonstrated. UAE has an important effect on the phenolic content and antioxidant capacity of olive leaves. Moreover, oleuropein-rich extract can have potential as a therapeutic agent depending on its antimicrobial and DNA-protecting activity. UAE process was optimized to obtain oleuropein-enriched olive leaf extract. Bioactive, DNA damage protecting, and aroma properties of the extracts were evaluated. Regarding the high antioxidant capacity and DNA damage-protecting activity, oleuropein-rich extracts obtained optimized probe-based UAE could have the potential to be used as a natural antioxidant compound in the food industry. image
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    Fourier transform-infrared assessment of cholesterol effect on antibiotic resistance of Salmonella Typhimurium
    (Wiley-Hindawi, 2022) Ilgaz, Ceren; Kadiroglu, Pinar
    In this study, the effect of cholesterol on antibiotic resistance of Salmonella Typhimurium was investigated. Antibiotic resistance patterns revealed that the bacterium was susceptible to ampicillin, streptomycin, sulfamethoxazole/trimethoprim, ciprofloxacin, tetracycline, chloramphenicol, and gentamicin and resistant to penicillin, erythromycin, and vancomycin. The minimum inhibitory concentrations (MICs) of ampicillin, streptomycin, ciprofloxacin, and sulfamethoxazole/ trimethoprim antibiotics were found as 16, 128, 0.25, and 16 mg/L, respectively. When the effect of cholesterol on antibiotic resistivity was examined, it was found that MICs increased in cholesterol medium than in non-cholesterol medium. The increase in MICs and decrement in inhibition zones was considered as the decreasing effect of cholesterol on the sensitivity of Salmonella Typhimurium. The effect of cholesterol on the antibiotic sensitivity of Salmonella Typhimurium was also assessed by Fourier transformed infrared (FT-IR) spectroscopy, and the results indicated that new functional groups were observed at different wavelengths in the presence of cholesterol. Practical applications Antibiotic resistance is a global phenomenon resulting in the emergence of pathogens with resistance to clinically important antibiotics. Antibiotic resistance in foodborne pathogens such as Salmonella is a major concern for public health safety. Significant increase in bacterial resistance makes it increasingly necessary to develop new drugs and antibiotic activity modifiers and effective techniques for treatment. Fourier transformed infrared (FT-IR) can be used as a rapid and precise method for the assessment of cholesterol effect on antibiotic resistance pattern of Salmonella Typhimurium.
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    Influence of pasteurization and storage conditions on microbiological quality and aroma profiles of shalgam
    (Elsevier, 2021) Kirlangic, Ozan; Ilgaz, Ceren; Kadiroglu, Pinar
    Shalgam is a traditional Turkish fermented beverage produced by the lactic acid fermentation of black carrot, salt, sourdough, bulgur flour and drinkable water. Aroma and microbial profiles of shalgams were examined based on the effect of pasteurization and storage parameters. At the beginning of the storage, the pH of the samples was 3.89, the acidity was 6.06-6.66 g/L and the brix values ranged from 2.67 to 2.73, at the end of storage these values were 3.89-3.98 for pH, 5.94-6.49 g/L for total acidity and 3.07-3.27% for brix. Total aerobic mesophilic bacteria decreased in unpasteurized sample, although the number of lactic acid bacteria increased and yeast and molds stored at 4 degrees C increased with storage time. A total amount of 32 and 35 volatiles were identified and amount of these compounds decreased during storage for unpasteurized and pasteurized samples, respectively. The total amount of volatiles, which was 1558.63-2179.49 mu g/L at the beginning of storage, decreased to 556.70-800.12 mu g/L at the end of storage. Samples were separated successfully according to storage times in terms of aroma profiles by principal component analysis (PCA). While the samples of shalgam stored for 0 and 7 days were characterized by most of the volatile compounds, samples stored for 14 and 30 days were characterized by ethyl alcohol, 4-phenyl-3-buten-2-one and myristicin. When effect of pasteurization process and storage parameters were evaluated comparatively, storage time and temperature were found more effective on shalgam quality.
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    Next-generation sequencing of shalgam flavor influencing microflora
    (Wiley, 2022) Ekici, Halil; Kadiroglu, Pinar; Ilgaz, Ceren
    Shalgam is a fermented sour beverage produced by lactic acid fermentation of black carrots. In this study, some physicochemical analyses and microbial counts of the shalgam samples were analyzed. Dominant lactic acid bacteria (LAB) and yeast-mold species and their composition were determined using next-generation sequencing (NGS) methods and volatile compounds profiles of shalgams were performed during the fermentation process. The total number of bacteria decreased gradually and the number of LAB and yeast increased gradually. The dominant types of LAB in the fermentation process were determined as Leuconostoc mesenteroides, Lactococcus lactis, and Leuconostoc pseudomesenteroides and the dominant yeast species were Saccharomyces cerevisiae and Candida boidinii. Ethyl alcohol was the dominant volatile compound in shalgam. Phenol and 2,4-bis(1,1-dimethylethyl) had lower percentage in total volatile compounds. Novelty impact statement Microbial profile and flavor changes were analyzed during fermentation in shalgam using real-time PCR and next-generation sequencing methods. Dominant species lactic acid bacteria species in shalgam were L. mesenteroides, L. lactis, and L. pseudomesenteroides and, S. cerevisiae and C. boidinii the dominant yeast species. Terpenes and alcohols were main volatile compounds of shalgam during fermentation. Quality of shalgam is closely related to the microbial flora, mainly LAB, of fermentation. Species determined in this study will be the source to select the starter cultures for future studies and then for industrial usage.
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    Ultrasound-Assisted Extraction of Hydroxytyrosol from Lactiplantibacillus plantarum Fermented Olive Leaves: Process Optimization and Bioactivity Assessment
    (Mdpi, 2023) Ilgaz, Ceren; Kelebek, Haşim; Kadiroglu, Pinar
    Olive leaves are important by-products for the recovery of phenolic compounds and extracts with high phenolic content using lactic acid bacteria during fermentation. Lactiplantibacillus plantarum (L. plantarum) strains as glucosidase-positive strains are starter cultures used to control the fermentation process. The main objective of the present work is to determine the most effective strain for the biodegradation of oleuropein to hydroxytyrosol using two L. plantarum strains for the fermentation of olive leaves. Box-Behnken experimental design was applied to determine the optimum ultrasound-assisted extraction (UAE) conditions to obtain hydroxytyrosol-rich extract using the brine of the fermented leaves. L. plantarum ATCC 14917 (hydroxytyrosol; 126.89 & PLUSMN; 1.59 mg/L) strain showed higher oleuropeinolytic activity than L. plantarum ATCC-BAA 793 (85.93 & PLUSMN; 0.70 mg/L) in olive leaf brine. When the UAE method was applied, it was seen that the hydroxytyrosol concentration of samples that were inoculated with L. plantarum ATCC 14917 (362.29 & PLUSMN; 2.31 mg/L) compared to L. plantarum ATCC-BAA 793 (248.79 & PLUSMN; 4.14) increased. The optimum UAE conditions were determined as 30% amplitude-5 min-30% ethanol for ATCC 14917 and 45% amplitude-9 min-10% ethanol for BAA 793 strain. This study showed that the brines of fermented olive leaves with oleuropeinolytic strains can be considered high added value products.