Browsing by Author "Boyacioglu, Dilek"

Now showing 1 - 12 of 12

Citation Count: 3
A Case Study to Assess the Sample Preparation Error in Pesticide Residue Analysis
(Springer, 2015) Omeroglu, Perihan Yolci; Ambrus, Arpad; Boyacioglu, Dilek; Majzik, Etelka Solymosne
In the scope of this study, pesticide residue distribution within a fruit and the possible error deriving from sample preparation step were demonstrated with the analysis of benomyl residues in peel, pulp, and seeds of papaya fruits treated post-harvest. Benomyl residue, measured as carbendazim, in corresponding sections of peel and pulp of papaya fruits ranged from 0.178 to 1.325 mg/kg and 0.025 to 0.087 mg/kg, respectively. Residue concentration decreased in a range between 41 and 83 % by peeling of papaya. All seeds contained residue value below limit of quantification. As the residues are unevenly distributed among the peel, pulp, and seed, pesticide residue analysis should be carried out accurately according to proper sample preparation protocol in peel, pulp, or in whole fruit and evaluated correctly taking into consideration the purpose of the analysis. The proportion of peel and pulp after their separation significantly affected the residues measured in the peel and pulp. It shows how peeling operation can affect the results and how important it is to remove the peel without significant portion of pulp attached to it. Thus, the selected test system could be well used to demonstrate the possible variability of measured residues depending on the uniformity of sample preparation.
Citation Count: 13
Effects of Honey Addition on Antioxidative Properties of Different Herbal Teas
(inst Animal Reproduction & Food Research Polish Acad Sciences Olsztyn, 2015) Toydemir, Gamze; Capanoglu, Esra; Kamiloglu, Senem; Firatligil-Durmus, Ebru; Sunay, Asli E.; Samanci, Taylan; Boyacioglu, Dilek
Tea and herbal infusions are among the major contributors of phenolic compounds, specifically flavonoids, in our daily diet. Honey is another antioxidant-rich food that is widely used as a natural sweetener. In this work, the effects of honey addition on antioxidant properties of different herbal teas were investigated. For this purpose, 2 different types of honey (flower and pine honey) were added into 9 different herbal teas (melissa, green tea, rosehip, sage, echinacea, fennel, linden, daisy, and ginger) at 4 different temperatures (55 degrees C, 65 degrees C, 75 degrees C, and 85 degrees C), and the changes in the content of total pheolics, total flavonoids, and total antioxidant capacity were determined. The total phenolic content and the total antioxidant capacity of the honey-added-tea samples were found to be increased (up to 57% for both), especially with pine honey and at higher temperatures of honey addition. The findings of this study supported the use of honey as a natural sweetener in tea in order to be able to benefit from the health-enhancing antioxidative properties of these two promising food products.
Citation Count: 62
The effects of juice processing on black mulberry antioxidants
(Elsevier Sci Ltd, 2015) Tomas, Merve; Toydemir, Gamze; Boyacioglu, Dilek; Hall, Robert; Beekwilder, Jules; Capanoglu, Esra
Black mulberry fruit is processed to juice at significant scale in Turkey. The effect of industrial-scale juice production on black mulberry antioxidants was evaluated using samples collected from the main steps of processing; including the selection of fruits, washing, mechanical milling, mashing, cold pressing, pasteurization, and filling-packing. Two major anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside), two phenolic acids (3- and caffeoylquinic acid) and 3 flavonols (rutin, quercetin-3-glucoside, and quercetin-malonyl-glucoside) were identified using LC-QTOF-MS and were quantified using HPLC. Approximately, 60-70% of the fruit anthocyanins were retained in the final juice, which also contained high levels of caffeoylquinic acids, relative to the fruit. Mashing and pressing were the steps which were effective for the recovery of fruit polyphenolics into the juice fraction. Moreover, an in vitro gastrointestinal digestion model, applied to determine the effect of processing on the bioavailability of mulberry antioxidants, indicated a higher anthocyanin bioavailability for the fruit matrix than for the juice matrix. (C) 2014 Elsevier Ltd. All rights reserved.
Citation Count: 9
Estimation of Sample Processing Uncertainty of Large-Size Crops in Pesticide Residue Analysis
(Springer, 2013) Omeroglu, Perihan Yolci; Ambrus, Arpad; Boyacioglu, Dilek
Sample processing procedure should result in analytical portions that are representative of the analytical sample, even if 1-5 g portion are withdrawn from a large-size crops. Therefore, the efficiency of sample processing should be regularly tested during method validation and internal quality control studies. In the scope of this study, sample processing uncertainty was investigated by surface treatment of the cucumber, papaya, and jackfruit representing large-size crops with radio-labelled chlorpyrifos methyl. After homogenization in a chopper, five small and five large test portions were withdrawn from "statistically" well-mixed materials and their residue content was determined with liquid scintillation counter, which provided a quick and well reproducible mode of quantitative determination of residues. The efficiency of sample processing characterized with the sampling constant, changed between 0.78 and 3.01 kg with typical value of 1.61 kg for processing at ambient temperature. Once the sampling constant was established, it was used to predict the uncertainty of sample processing for different test portion sizes. Uncertainty of sample processing at 30 g analytical portion varied between 4.70 and 10.55 %. Furthermore, addition of dry ice to papaya resulted in well-mixed samples as well as 50 % reduction in sampling constant value.
Citation Count: 21
Evaluation of Turkish propolis for its chemical composition, antioxidant capacity, anti-proliferative effect on several human breast cancer cell lines and proliferative effect on fibroblasts and mouse mesenchymal stem cell line
(Taylor & Francis Ltd, 2018) Ozdal, Tugba; Sari-Kaplan, Gulce; Mutlu-Altundag, Ergul; Boyacioglu, Dilek; Capanoglu, Esra
Propolis is an extremely complex resinous natural compound collected by honey bees from various plant sources and exhibits pharmacological and biological properties attributed to the presence of polyphenols. This study examined the total phenolic and flavonoid contents as well as the total antioxidant capacity using 2,2 '-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), cupric-reducing antioxidant capacity (CUPRAC), and ferric-reducing antioxidant power (FRAP) methods. Turkish propolis has very high total phenolic (314.36 +/- 3.65 mg GAE/g propolis) and total flavonoid contents (522.71 +/- 11.45 mg QE/g propolis). The highest antioxidant capacity value was obtained by the CUPRAC method (1184.94 +/- 63.27 mg TE/g propolis). Phenolic profile of Turkish propolis was also determined by high performance liquid chromatography with photodiode array detection (HPLC-PDA) method. The main phenolic compounds identified in Turkish propolis was flavonoids including pinocembrin > chrysin > galangin > pinobanksin > pinostrobin and phenolic acids including caffeic acid > p-coumaric acid > ferrulic acid > t-cinnamic acid. In the present work, anti-proliferative and proliferative effects of propolis extracts were also investigated on two different breast cancer cell lines; MDA-MB-231, UACC-3199 and on two normal cell lines; fibroblasts and mouse mesenchymal stem cell lines. According to the XTT results, Turkish propolis sample showed significant anti-proliferative effect on MDA-MB-231 and UACC breast cancer cell lines. Interestingly, Turkish propolis sample had proliferative effect on both fibroblasts and mouse mesenchymal stem cells. These results suggest that Turkish propolis can be considered as a potent agent on breast cancer treatment for further investigations.
Citation Count: 40
Fruit Antioxidants during Vinegar Processing: Changes in Content and in Vitro Bio-Accessibility
(Mdpi, 2016) Bakir, Sena; Toydemir, Gamze; Boyacioglu, Dilek; Beekwilder, Jules; Capanoglu, Esra
Background: Vinegars based on fruit juices could conserve part of the health-associated compounds present in the fruits. However, in general very limited knowledge exists on the consequences of vinegar-making on different antioxidant compounds from fruit. In this study vinegars derived from apple and grape are studied. Methods: A number of steps, starting from the fermentation of the fruit juices to the formation of the final vinegars, were studied from an industrial vinegar process. The effect of each of the vinegar processing steps on content of antioxidants, phenolic compounds and flavonoids was studied, by spectroscopic methods and by high-performance liquid chromatography (HPLC). Results: The major observation was that spectrophotometric methods indicate a strong loss of antioxidant phenolic compounds during the transition from fruit wine to fruit vinegar. A targeted HPLC analysis indicates that metabolites such as gallic acid are lost in later stages of the vinegar process. Conclusion: The major conclusion of this work is that major changes occur in phenolic compounds during vinegar making. An untargeted metabolite analysis should be used to reveal these changes in more detail. In addition, the effect of vinegar processing on bio-accessibility of phenolic compounds was investigated by mimicking the digestive tract in an in vitro set up. This study is meant to provide insight into the potential of vinegar as a source of health-related compounds from fruit.
Citation Count: 91
Home-Processed Red Beetroot (Beta vulgaris L.) Products: Changes in Antioxidant Properties and Bioaccessibility
(Mdpi, 2016) Guldiken, Burcu; Toydemir, Gamze; Memis, Kubra Nur; Okur, Sena; Boyacioglu, Dilek; Capanoglu, Esra
In this study, the effects of home-processing on the antioxidant properties and in vitro bioaccessibility of red beetroot bioactives were investigated. For this purpose, fresh red beetroot and six different home-processed red beetroot products-including boiled, oven-dried, pickled, pureed, juice-processed, and jam-processed-were analyzed and compared for their total phenolic (TP) and total flavonoid (TF) contents, total antioxidant capacities (TAC), and individual anthocyanin contents. In addition, bioaccessibility of red beetroot antioxidants was determined using an in vitro simulated gastrointestinal digestion method. Dried, pureed, and fresh red beetroot samples had the highest TP, TF, and TAC values, which were 347 +/- 23 mg gallic acid equivalent (GAE)/100 g, 289 +/- 53 mg rutin equivalent (RE)/100 g, 3889 +/- 982 mg trolox equivalent antioxidant capacity (TEAC)/100 g, respectively. The in vitro digestion method revealed the highest recovery for TP (16%) and TAC (1.3%) in jam. This study provides comparative data to evaluate the effects of various home-processing techniques on antioxidant potential of red beetroot products.
Citation Count: 20
An Overview on Steps of Pesticide Residue Analysis and Contribution of the Individual Steps to the Measurement Uncertainty
(Springer, 2012) Omeroglu, Perihan Yolci; Boyacioglu, Dilek; Ambrus, Arpad; Karaali, Artemis; Saner, Samim
To facilitate the international food trade as well as to protect consumers from exposure to unacceptable pesticide residue levels, Codex Alimentarius Commission, European Union, and National Authorities set maximum residue limits for different food commodities. The control of pesticide residues at national and international level requires reliable and comparable analytical data that can be obtained by applying validated methods and implementing an effective internal quality control and quality assurance system in the testing laboratories. For the correct interpretation of the analytical results, measurement uncertainty should be estimated. Pesticide residue analysis includes two main steps: sampling performed outside of the laboratory and laboratory operations comprising of sample preparation, sample size reduction, sample processing, extraction, cleanup, and chromatographic determination. By taking into consideration the contribution of the individual steps to the overall uncertainty of the results, the analytical procedures can be optimized to fit for the purpose of the analysis with minimum cost. The scope of this paper is to review major steps of pesticide residue analysis in the light of current developments, to highlight the importance of identification and estimation of the uncertainties associated with the results, to describe suitable methods for their estimation, and to summarize the contribution of each step to the combined uncertainty.
Citation Count: 67
Potential Use of Turkish Medicinal Plants in the Treatment of Various Diseases
(Mdpi Ag, 2016) Ozkan, Gulay; Kamiloglu, Senem; Ozdal, Tugba; Boyacioglu, Dilek; Capanoglu, Esra
Medicinal plants are sources of health-promoting substances, including phytochemicals and phytoalexins that comprise polyphenols, flavonoids, carotenoids, vitamins A, C, E and several other constituents. Many studies have indicated that medicinal plants have been used to treat human diseases for thousands of years owing to their antimicrobial and antioxidant activities. Medicinal plants reduce the oxidative stress in cells and prevent cancer, cardiovascular and inflammatory diseases, neurodegenerative and digestive system disorders. These potential beneficial effects have been attributed to the presence of bioactive compounds that show antioxidant properties by acting as free radical scavengers or metal chelators, reducing the reactions that produce reactive oxygen and nitrogen species (ROS/RNS). Considering the importance of medicinal plants in terms of their beneficial health effects, some of the medicinally important plants grown in Turkey are covered in this review with respect to their antioxidant potential and phytochemical profile.
Citation Count: 43
Processing black mulberry into jam: effects on antioxidant potential and in vitro bioaccessibility
(Wiley, 2017) Tomas, Merve; Toydemir, Gamze; Boyacioglu, Dilek; Hall, Robert D.; Beekwilder, Jules; Capanoglu, Esra
BACKGROUNDBlack mulberries (Morus nigra) were processed into jam on an industrialised scale, including the major steps of: selection of frozen black mulberries, adding glucose-fructose syrup and water, cooking, adding citric acid and apple pectin, removing seeds, and pasteurisation. Qualitative and quantitative determinations of antioxidants in black mulberry samples were performed using spectrophotometric methods, as well as HPLC- and LC-QTOF-MS-based measurements. These analyses included the determination of total polyphenolic content, % polymeric colour, total and individual anthocyanin contents, antioxidant capacity, and in vitro bioaccessibility in processing samples. RESULTSJam processing led to a significant reduction in total phenolics (88%), total flavonoids (89%), anthocyanins (97%), and antioxidant capacity (88-93%) (P < 0.05). Individual anthocyanin contents, determined using HPLC analysis, also showed a significant decrease (approximate to 99% loss). In contrast, % recovery of bioaccessible total phenolics, anthocyanins, and antioxidant capacity (ABTS assay) increased after jam processing (16%, 12%, and 37%, respectively). CONCLUSIONFruit processing resulted in losses of polyphenols, anthocyanins, and antioxidant capacity of black mulberry jam. Optimisation of food processing could help to protect the phenolic compounds in fruits which might be helpful for the food industry to minimise the antioxidant loss and improve the final product quality. (c) 2016 Society of Chemical Industry
Citation Count: 549
The Reciprocal Interactions between Polyphenols and Gut Microbiota and Effects on Bioaccessibility
(Mdpi, 2016) Ozdal, Tugba; Sela, David A.; Xiao, Jianbo; Boyacioglu, Dilek; Chen, Fang; Capanoglu, Esra
As of late, polyphenols have increasingly interested the scientific community due to their proposed health benefits. Much of this attention has focused on their bioavailability. Polyphenol-gut microbiota interactions should be considered to understand their biological functions. The dichotomy between the biotransformation of polyphenols into their metabolites by gut microbiota and the modulation of gut microbiota composition by polyphenols contributes to positive health outcomes. Although there are many studies on the in vivo bioavailability of polyphenols, the mutual relationship between polyphenols and gut microbiota is not fully understood. This review focuses on the biotransformation of polyphenols by gut microbiota, modulation of gut microbiota by polyphenols, and the effects of these two-way mutual interactions on polyphenol bioavailability, and ultimately, human health.
Citation Count: 157
A Review on the Effect of Drying on Antioxidant Potential of Fruits and Vegetables
(Taylor & Francis inc, 2016) Kamiloglu, Senem; Toydemir, Gamze; Boyacioglu, Dilek; Beekwilder, Jules; Hall, Robert D.; Capanoglu, Esra
The role of antioxidants in human nutrition has gained increased interest, especially due to their associated health beneficial effects for a number of chronic diseases, including cardiovascular diseases and certain types of cancer. Fruits and vegetables are perishable and difficult to preserve as fresh products. Dried fruits and vegetables can be easily stored, transported at relatively low cost, have reduced packing costs, and their low water content delays microbial spoilage. Air-, freeze-, microwave- and sun-drying are among the most thoroughly studied drying methods. This review provides an overview of recent findings on the effects of different drying techniques on major antioxidants of fruits and vegetables. In particular, changes in ascorbic acid, carotenoids, flavonoids, phenolic acids, total phenolics, and antioxidant activity are discussed in detail.