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    Combined effects of acidification and high-pressure processing on microbial inactivation, bioactive compounds and antioxidant activity of liquorice root sherbet
    (2021) Aday, Serpil; Pala, Cigdem Uysal; Cam, Belgizar Ayana; Bulut, Sami
    High Hydrostatic Pressure Processing (HPP) has gained more attention in the fruit and vegetable industry in recent years. In this study, the optimal acidification parameters (citric acid alone and combination with ascorbic acid at the pH range 3.0 to 4.5) were determined and the effect of HPP conditions (pressures 250- 450 MPa and exposure times 1-5 min) on acidified liquorice root sherbet (ALRS) were investigated. Results showed that acidification of LRS by only citric acid had higher aroma and flavor scores. HP treatments were effective to reduce the yeast and mould (YM) count, total coliforms (TC), and inoculated pathogens (Escherichia coli ATCC 25922 and Salmonella Typhimurium ATCC 14028) in ALRS. Although acidification of LRS achieved a significant reduction in glycyrrhizic acid (GA) content, further treatment by HPP did not affect pH, the contents of total phenolic, total soluble solids, flavonoid, and GA or the antioxidant capacity of ALRS. Our results suggests that acidification and HPP treatments could be used to increase the consumer acceptability and extend the shelf life of LRS.
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    Effect of UV-C light on anthocyanin content and other quality parameters of pomegranate juice
    (Academic Press Inc Elsevier Science, 2011) Pala, Cigdem Uysal; Toklucu, Aysegul Kirca
    Pomegranate juice (PJ) was subjected to UV-C irradiation as a non-thermal technology and changes in major quality characteristics of juice such as anthocyanins, polymeric colour, antioxidant activity and total phenol content were determined. The results were compared with control (untreated) and heat treated (at 90 degrees C, 2 min) juice samples. UV-C treatment preserved the major quality characteristics of pomegranate juice better than heating process. After UV-C treatment, total monomeric anthocyanin content of pomegranate juice did not change significantly and decrease in individual anthocyanin pigments were between 8.1% and 16.3%. However, anthocyanin content of PJ was significantly affected by heat treatment (P < 0.05) and 15.4% and 28.3% of individual anthocyanin pigments were lost after this process. Also, differences between the control and UV-C treated PJ samples were small in terms of polymeric colour values (P > 0.05) while polymeric colour of PJ were significantly affected by heat treatment (P < 0.05). There were no significant changes in antioxidant capacity evaluated by trolox equivalent antioxidant capacity (TEAC) assay and total phenol contents of PJ after UV-C and heat treatments. The effectiveness of the UV-C system on the aerobic plate count, yeast and mould count and Esherichia coli ATCC 25922 as a surrogate microorganism of E. cola O157:H7 in PJ resulted in 1.8, 1.45 and 6.15 log reductions, respectively. (C) 2011 Elsevier Inc. All rights reserved.
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    Effects of UV-C Light Processing on Some Quality Characteristics of Grape Juices
    (Springer, 2013) Pala, Cigdem Uysal; Toklucu, Aysegul Kirca
    White and red grape juices (GJs) were subjected to ultraviolet C (UV-C) light as a non-thermal preservation technology using a coiled tube UV-C reactor with nine lamps. The effects of UV-C light on microbial (total aerobic count and yeast and mould count) and some chemical quality characteristics (total phenolics, antioxidant capacity, anthocyanin and polymeric colour, etc.) of white and red GJs were investigated. The results were compared with control (untreated) and heat-treated juice samples. Single-pass UV-C treatment (12.6 J/mL) of white and red GJs resulted in 3.51 and 3.59 log reductions in total aerobic count and, 2.71 and 2.89 log reductions in yeast and mould counts, respectively. The microbial loads of both GJs were completely eliminated after two passes through the reactor (25.2 J/mL). After UV-C and heat treatments, there were no significant changes in antioxidant capacity, total phenolics, titratable acidity, soluble solids and pH of white and red GJs (P > 0.05). The losses in monomeric anthocyanins were 6.1% and 8.7% after UV-C treatment of 12.6 and 25.2 J/mL doses, respectively. However, anthocyanin level of red GJ was significantly affected by the heat treatment with an 11.8% loss (P < 0.05). The percent polymeric colour of the red GJ with heat treatment was significantly higher compared to the colour with the UV-C treatment.
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    Microbial Inactivation and Physicochemical Properties of Ultrasound Processed Pomegranate Juice
    (Int Assoc Food Protection, 2015) Pala, Cigdem Uysal; Zorba, Nukhet Nilufer Demirel; Ozcan, Gulcin
    The effects of ultrasound treatment at various amplitudes (50, 75, and 100%) and times (0, 6, 12, 18, 24, and 30 min) on Escherichia coli ATCC 25922 (a surrogate for E. coli O157:H7) and Saccharomyces cerevisiae ATCC 2366 levels and physicochemical characteristics (monomeric anthocyanins, color values, total phenolics, pH, and soluble solids) were determined in pomegranate juice. More than a 5-log inactivation of E. coli ATCC 25922 and a 1.36-log inactivation of S. cerevisiae ATCC 2366 were achieved after 30 min of ultrasound treatment at 100% amplitude. The log-linear and Weibull models were successfully used to estimate the microbial inactivation as a function of ultrasound treatment time (R-2 > 0.97). No significant changes were observed in total phenolics, pH, and soluble solids of the treated juice (P> 0.05). The ultrasound treatment for up to 30 min resulted in more than 92 and 89% anthocyanin retention at 75 and 100% amplitude, respectively. The redness (a*) of the juice did not change significantly after the ultrasound treatment at amplitudes of 75 and 100% for up to 24 and 12 min, respectively. No significant changes in L* and b* values were observed after ultrasound treatment at all amplitudes and after up to 30 min of treatment for 50 and 75% amplitudes. Small differences in juice color were noted based on total color difference scores.
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    Microbial, physicochemical and sensory properties of UV-C processed orange juice and its microbial stability during refrigerated storage
    (Elsevier, 2013) Pala, Cigdem Uysal; Toklucu, Aysegul Kirca
    The effect of the UV-C light on quality characteristics (microbiological, physicochemical and sensorial) and microbial stability of orange juice (OJ) during storage (4 and 10 degrees C) were investigated and the results were compared with untreated and heat treated (at 90 degrees C, 2 min) juice. UV-C treatment (36.09 kJ/L dose) of OJ resulted in 2.8 log and 0.34 log reductions in aerobic plate count and yeast & mould count, respectively. Also, a 5.72 log reduction in Escherichia coli ATCC 25922 after UV-C treatment (36.09 kJ/L dose) was achieved, which indicates an acceptable reduction of a potential pathogen in juices. Ascorbic acid content as a major quality parameter of OJ did not change significantly after the UV-C treatment (36.09 kJ/L dose). Differences between untreated and UV-C treated (48.12 kJ/L dose) OJ were small in terms of organic acids, antioxidant capacity and phenolics. Based on sensory analysis results, no significant differences were detected between fresh and UV-C treated juices, and UV-C treated OJ was preferred more than the heat treated juice. UV-C treatment partially extended the shelf life of fresh juice during storage at the refrigerated conditions. (C) 2012 Elsevier Ltd. All rights reserved.
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    Molecular Characterization of Natural Fungal Flora in Black Olives: From Field to Table
    (2017) Ozsoy, Nisa; Özkılınç, Hilal; Pala, Cigdem Uysal
    In this study, molecular markers were used to determine fungal flora in black olive fruitsfrom field surveys to the table, following the fermentation process. Field samples werecollected from different locations of Canakkale province, including Gokceada (Imbros),where organic farming is employed. Some of the fruits from field samples were used forblack table olive production and then fungal flora was tracked during the fermentationprocess. Fungal isolation was also conducted on some commercial samples. Fifty sevenisolates from field samples, 56 isolates from the fermentation process and 17 isolatesfrom commercial products were obtained. Among these isolates, 41 Alternaria, 43Penicillium, 19 Aspergillus, 8 Monascus and 19 other genera were determined usingamplified sizes of the Beta-tubulin gene region. Species level identification was carriedout based on sequences of Beta-tubulin amplicons, which provided accurateidentification, especially where the genera were morphologically highly similar. Theoccurrence and prevalence of fungal species changed in fungal collections from the fieldto the fermentation process. While Alternaria alternata was common in field samples,they were absent during fermentation. Many of these identified species, such asPenicillium expansum, Aspergillus niger and Monascus pilosus, which are known aspotential toxin producers such as aflatoxin, ochratoxin A and citrinin, were found both innatural and fermented samples, even at the end of the fermentation process. These resultsshowed that some fungal species which survive on olives from the field to the table arepotential toxin producers and can be successfully characterized by amplification andsequencing of Beta-tubulin gene.
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    Storage quality and microbiological safety of high pressure pasteurized liquorice root sherbet
    (Elsevier, 2018) Aday, Serpil; Pala, Cigdem Uysal; Cam, Belgizar Ayana; Bulut, Sami
    In this study, the effect of high pressure processing (HPP) on wide-range quality characteristics (microbial, physicochemical, bioactive compounds and sensory properties) of liquorice root sherbet (LRS) were investigated. Pressure levels of 250, 355 and 450 MPa for holding times of 1 min and 5 min were applied to LRS. Full inactivation of yeast and mold count (YMC) and total coliforms (TCs) were observed at pressure-time combinations more severe than 355 MPa-1m and 250 MPa-5m, respectively. More than 6 log reduction in inoculated E. coli ATCC 25922 and Salmonella Typhimurium ATCC 14028 were achieved when the inoculated samples were treated at 450 MPa for 5 m. Even 450 MPa of pressure for 5 m applied, there was a persisting resistant total aerobic count, total decrease about 2.7 log. No significant differences were observed between HPP-treated and control samples regarding their pH, soluble solids, total phenolics, total flavonoids, antioxidant activity and glycyrrhizic acid content (P > .05). Consumer acceptability test showed that no differences were found between 450 MPa and 5m HPP-treated and control LRS in terms of their flavor and appearance. As a result, HPP could be used to extend the shelf life of liquorice sherbet without changing its physicochemical composition.
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    The impact of ozone and equilibrium-modified atmosphere packaging on storage stability and health-promoting indicators of fresh Angelino plums
    (Sage Publications Ltd, 2024) Caner, Cengiz; Pala, Cigdem Uysal; Yuceer, Muhammed
    Effectiveness of ozone concentrations (2, 5, and 10 ppm) and exposure time (3 and 9 min) on selected physicochemical properties (pH, soluble solids, color values (L*, a*, and b*), and texture) and health-promoting indicators such as organic acids, total phenolics (TP), and anthocyanins of Angelino fresh plums was evaluated during storage (0, 30, 90, and 120 days) in equilibrium modified atmosphere packaging (EMAP). Total anthocyanin contents and organic acid profiles were significantly affected by storage times. Malic acid (MA) was the main organic acid in Angelino plums. MA content (4663 and 4764 mg/L) was the highest value in the ozonated 2-ppm/9-min and 5-ppm/3-min than other ozonated groups and also control at 120 days of the storage. The ozone treatments especially 2-ppm/9-min and 5-ppm/3 min can significantly retard the degradation of MA content (8294 to 2688-2694 mg/L) during the storage (p < .05). Total phenol content were most significantly decreased in the control during storage, with the loss at the level of 31.7% of TPs, while the lowest one 2-ppm/9-min (20.8%) and 5-ppm/-3 min (21.9%). The color and texture are maintained for the ozone applications compared to the control during storage. Ozonation with 2-ppm/9-min and 5-ppm/-3 min showed the best performance while maintaining the storage stability based on the physicochemical properties including hardness and bioactive compounds (such as anthocyanins and organic acids), visual appearance due to the more attractive color (L*, a*, b*) the plums.
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    The potential of near and mid-infrared spectroscopy for rapid quantification of oleuropein, total phenolics, total flavonoids and antioxidant activity in olive tree (Olea europaea) leaves
    (Springer, 2018) Can, Aygul; Ayvaz, Huseyin; Pala, Cigdem Uysal; Condelli, Nicola; Galgano, Fernanda; Tolve, Roberta
    Natural foods and food-related antioxidants such as phenolic phytochemicals are of great interest due to their preventive properties against oxidative damage. Olive tree leaves contain high quality and amount of phenolic compounds including oleuropein and therefore considered as nutraceutically valuable materials. The composition of olive leaves, its phenolics and antioxidant power are influenced by numerous factors causing great variation among samples. Additionally, traditional analytical methods performed to quantify these parameters in each product entail long and complicated sample preparation procedures, the use of toxic chemicals, skilled labors, instrumentation and sophisticated laboratory conditions. One appealing alternative is the use of infrared spectroscopy since it gives information about the food composition quickly and it is a multi-parametric and environmentally friendly choice. Therefore, we investigated the oleuropein, total phenolic content, total flavonoid content and antioxidant activity levels of 23 common cultivars of olive leaves harvested from Turkey and Italy using traditional reference methods and also developed near and mid-infrared based partial least squares regression (PLSR) models to predict these parameters without the need of sample preparation. Internal validations of the PLSR calibration models were done using full cross-validation and yielded very high correlation coefficients (0.95) and low errors in predictions (% standard error of cross-validation for parameters were lower than 7.54%). The levels of all the parameters of interest could be successfully predicted using both NIR and MIR instrumentation within seconds. Overall, infrared spectroscopy along with chemometrics exhibited great potential for future olive leave studies.