Browsing by Author "Toydemir, Gamze"

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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: 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: 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: 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.