Person: YILDIZ, ELİF
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YILDIZ
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ELİF
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Publication Impact of coffee silverskin on in-vitro viability of kefir culture during storage(Croatian Dairy Union, 2022-01-01) Değirmencioğlu, Nurcan; Özmen-Togay, Sine; GÜLDAŞ, METİN; ÖZMEN TOĞAY, SİNE; Gülkün, Günnur; YILDIZ, ELİF; Yıldız, Elif; Sahan, Yasemin; ŞAHAN, YASEMİN; Gürbüz, Ozan; GÜRBÜZ, OZAN; Ziraat Fakültesi; 0000-0002-5187-9380; 0000-0003-1356-9012; 0000-0001-7871-1628; GLT-7125-2022; AAG-6424-2021; U-1332-2019Probiotic dairy products must contain a certain level of live probiotic microorganisms at the time of consumption. The number of live microorganisms in kefir culture, which is a mixture of different microorganisms, may change during storage due to various factors. In this study, the effects of adding a novel ingredient coffee bean membrane (CSS-coffee silverskin), on the viability of microorganisms contained in kefir culture were investigated. For this purpose, CSS obtained from 2 different coffee varieties (Arabica and Robusta) was added to kefir samples at 3 different concentrations (0.5, 0.75 and 1.0 %) at the beginning of fermentation. It was observed that especially the addition of CSS belonging to the Robusta variety significantly increased the viability of lactic acid bacteria (lactobacilli and lactococci) which accounted for 88-94.10 % and 82.37-92.44 % respectively. During the storage period of 28 days at 4 degrees C; it could be observed that kefir enrichment with CSS of both coffee varieties increased the viability of lactobacilli and lactococci after in-vitro digestion, depending on the rate of supplementation. Number of yeasts was decreased during the storage.Publication Antioxidant and anti-diabetic properties of spirulina platensis produced in Turkey(Soc Brasileira Ciencia Tecnologia Alimentos, 2021-07-01) Güldaş, Metin; Ziyanok-Demirtaş, Sedef; Şahan, Yasemin; Yıldız, Elif; Gürbüz, Ozan; GÜLDAŞ, METİN; ZİYANOK DEMİRTAŞ, SEDEF; ŞAHAN, YASEMİN; YILDIZ, ELİF; GÜRBÜZ, OZAN; Sağlık Bilimleri Fakültesi; Gıda Mühendisliği Bölümü; 0000-0002-5187-9380; 0000-0003-3878-3808; 0000-0003-1356-9012; 0000-0001-7871-1628; ABE-6748-2020; GLT-7125-2022; AAG-6424-2021; AAH-4272-2021; U-1332-2019Spirulina produced in Turkey has a high antioxidant capacity determined by the three common methods (ABTS, CUPRAC, and DPPH). The major phenolics found in Spirulina were acacetin (53.62%) and pinocembrin (41.28%). The bio-accessibility values of the phenolic compounds in Spirulina were approximately 60%. PUFas are the significant antioxidant compounds to prevent lipid peroxidation. Spirulina has been found to reduce blood sugar and oxidative stress due probably to the high amount of omega-6 PUFA. By the treatment of Spirulina, the levels of antioxidant enzymes (GSH-Px and SOD) were increased 240 and 60% in the healthy rats, while 19 and 59% in the diabetics. In diabetic rats fed with Spirulina, glucose, triglyceride, total cholesterol levels in blood and malondialdehyde content in body tissues were decreased by 20, 31, 22 and up to 56%, respectively. In-vitro and in-vivo tests have shown that Spirulina has anti-hyperglycaemic, anti-hyperlipidaemia and antioxidative effects on diabetic rats.Publication Oxidative stress and antioxidants-a critical review on in vitro antioxidant assays(Mdpi, 2022-12-01) Kotha, Raghavendhar R. R.; Tareq, Fakir Shahidullah; Luthria, Devanand L. L.; Yıldız, Elif; YILDIZ, ELİF; Keleş Meslek Yüksekokulu; 0000-0003-1356-9012; AAG-6424-2021Antioxidants have been widely studied in the fields of biology, medicine, food, and nutrition sciences. There has been extensive work on developing assays for foods and biological systems. The scientific communities have well-accepted the effectiveness of endogenous antioxidants generated in the body. However, the health efficacy and the possible action of exogenous dietary antioxidants are still questionable. This may be attributed to several factors, including a lack of basic understanding of the interaction of exogenous antioxidants in the body, the lack of agreement of the different antioxidant assays, and the lack of specificity of the assays, which leads to an inability to relate specific dietary antioxidants to health outcomes. Hence, there is significant doubt regarding the relationship between dietary antioxidants to human health. In this review, we documented the variations in the current methodologies, their mechanisms, and the highly varying values for six common food substrates (fruits, vegetables, processed foods, grains, legumes, milk, and dairy-related products). Finally, we discuss the strengths and weaknesses of the antioxidant assays and examine the challenges in correlating the antioxidant activity of foods to human health.Publication Characterization of fruit vinegars via bioactive and organic acid profile using chemometrics(Mdpi, 2023-10-01) Yıldız, Elif; YILDIZ, ELİF; Keleş Meslek Yüksekokulu; 0000-0003-1356-9012; AAG-6424-2021Vinegar has been known as a traditional remedy since ancient times. In addition to being used as a flavoring and aroma enhancer in world cuisines, it has attracted more and more attention due to its bioactive potential and health properties. Although the most common use is apple cider vinegar together with grape vinegar, vinegar produced from red fruits has come to the fore due to their health purposes. Rosehip, pomegranate, fig, guelder-rose, blackberry, raspberry, and blueberry vinegars were evaluated regarding the organic acid content, phenolic compound content, and bioactive potential to assess their health potential and associated contents. Acetic acid, citric acid, succinic acid, and malic acid were determined as prominent organic acids in the vinegar samples. In contrast, gallic acid, vanillic acid, protocatechuic acid, and ferulic acid were dominant regarding phenolic compounds. Raspberry, guelder-rose, and pomegranate vinegars came forth regarding their bioactive content and potential. The discriminative parameters of the vinegar samples were pH, total acidity, dL-isocitric acid, gallic acid, and hydroxybenzoic acid. Fruit vinegars were determined to have a notable bioactive content compared to apple and grape vinegars. The use of these vulnerable bioactive materials in vinegar fermentation could provide an effective way for nutrition and raw material resourcing.Publication Effects of honey enrichment with Spirulina platensis on phenolics, bioaccessibility, antioxidant capacity and fatty acids(Elsevier, 2021-09-12) Güldaş, Metin; Gürbüz, Ozan; Çakmak, İbrahim; Yıldız, Elif; Şen, Hasan; GÜLDAŞ, METİN; GÜRBÜZ, OZAN; ÇAKMAK, İBRAHİM; YILDIZ, ELİF; Sağlık Bilimleri Fakültesi; Gıda Teknolojisi Bölümü; 0000-0002-5187-9380; 0000-0001-7871-1628; 0000-0003-1356-9012; GLT-7125-2022; AAG-6424-2021; U-1332-2019; KFC-1744-2024The honeybees have been fed by Spirulina platensis extract and algal honey with green color produced by the bees naturally was obtained the first time in order to enhance its medicinal properties, mainly antioxidant properties. Antioxidant capacity, bioaccessibility of phenolics, hydrolysable and extractable phenolics, sugar, phenolic and fatty acid profiles were determined in the Spirulina honey. Total phenolic content of the Spirulina honey was 14.37 mg GAE/100g and increased 28.53% with Spirulina enrichment. Antioxidant capacities of the Spirulina honey were determined as 6.31, 5.85 and 3.66 mu mol Trolox/g by ABTS, CUPRAC and DPPH methods in bioaccessible extracts. No significant difference was observed between control and Spirulina honey samples in terms of bioaccessibility of the total phenolics (p <= 0.01). Among the detected phenolic compounds (15 phenolics), acacetin (48.55%) and pinocembrine (47.13%) were the highest. Total phenolic content of the honey can be enriched up to 20% by feeding of the honey bees with 10% of Spirulina. Saccharose content in Spirulina honey was lower than the control honey as 4.42%.Publication Effect of drying methods and pre-treatments on bioactive potential of persimmon ( diospyros kaki l.)(Springer, 2023-12-28) Yıldız, Elif; YILDIZ, ELİF; Yılmaz, Aslıhan; YILMAZ, ASLIHAN; Gürbü, Ozan; Alibaş, İlknur; ALİBAŞ, İLKNUR; GÜRBÜZ, OZAN; Ziraat Fakültesi; Gıda Mühendisliği Bölümü; 0000-0003-1356-9012; 0000-0002-4913-905X; 0000-0002-1898-8390; AAY-2088-2021In this research, persimmon samples (sliced, pureed) were dehydrated by convective (50 and 100 degrees C) and microwave (100 W) drying techniques with different pre-treatment combinations of sugar addition (25%) and blanching (100 degrees C, 5 min). Each pre-treatment consisting of sugar addition, slicing, and blanching resulted in a significant increase in color parameters compared to unpretreated samples. Color parameters measured at low drying temperatures were lower than high ones. Also, 100 W dried samples were higher in total anthocyanin content, and the pureed samples were 24.80% higher than sliced ones. The bioactive potential was evaluated regarding extractable, hydrolysable, and bioaccessible phenolic fractions by total phenolic content and ABTS (2,2 '-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl) and CUPRAC (Cupric Reducing Antioxidant Capacity) antioxidant capacity assays. (i) 50 degrees C drying prevailed on drying at 100 degrees C and 100 W, especially in terms of extractable phenolic fractions and bioaccessible phenolic fractions; (ii) Sliced samples were higher for EPF and BPF, while pureed ones were higher in hydrolysable phenolic fractions; (iii) Blanched samples were relatively higher than unblanched ones in total phenolic content. For antioxidant capacity assays, extractable phenolic fractions were higher in blanched samples and bioaccessible phenolic fractions in unblanched ones (TEAC(ABTS), TEAC(CUPRAC)). (iv) Sugar addition negatively affected the bioactive potential in persimmon samples; no-sugar-added samples were higher, especially in bioaccessible phenolic fractions (p < 0.01; Total phenolic content, TEAC(ABTS,) TEAC(CUPRAC)). (v) The CUPRAC assay was the most appropriate method due to providing a view of more statistical distinction by picturing the same potential.Publication Phenolics, antioxidant capacity and bioaccessibility of kombucha tea(Amer Chemical Soc, 2019-03-31) Değirmencioğlu, Nurcan; Yıldız, Elif; Şahan, Yasemin; Güldaş, Metin; Gürbüz, Ozan; YILDIZ, ELİF; ŞAHAN, YASEMİN; Fen Bilimleri Enstitüsü; Gıda Mühendisliği Bölümü; 0000-0003-3457-251X ; 0000-0003-1356-9012 ; AAG-6424-2021; ABE-6748-2020Publication Use of coffee silverskin to improve the functional properties of cookies(Springer India, 2019-06-01) GÖÇMEN, DUYGU; ŞAHAN, YASEMİN; YILDIZ, ELİF; Yıldız, Elif; Coşkun, Meral; Aroufai, Idriss Amit; Ziraat Fakültesi; Gıda Mühendisliği Bölümü; 0000-0003-1356-9012; AAG-6424-2021; ABE-6748-2020; KDP-3344-2024The purpose of this study was to determine the suitability of coffee silverskin (CSS) supplementation to enhance phenolic content and antioxidant capacity of cookies. Cookie samples were prepared with partial replacement of wheat flour by CSS (2.5, 5.0, and 7.5%). Spread ratios were found lower in all cookies with CSS than in control. Cookies became darker with increasing levels of CSS. This is due to the fact that CSS has a dark color like cocoa. CSS supplementation had improved functional quality of cookies by increasing phenolic contents, antioxidant capacities, and in vitro bioaccessibilities of them. According to the sensory evaluation, all samples with CSS received 6 and above scores (6: like slightly, 7: like moderately) for all attributes from the panelists. The results demonstrated that CSS supplementation have a good potential for developing functional and acceptable cookies and similar bakery products.Publication Changes in bioaccessibility, phenolic content and antioxidant capacity of novel crackers with turmeric (Curcuma longa l.) and mahaleb (Prunus mahaleb l.) powders(Wageningen Academic Publishers, 2019-01-01) Yıldız, Elif; Güngör, G.; Yılmaz, H.; Göçmen, Duygu; YILDIZ, ELİF; Güngör, G.; Yılmaz, H.; GÖÇMEN, DUYGU; Ziraat Fakültesi; Gıda Mühendisliği Bölümü; 0000-0003-1356-9012; 0000-0003-0557-1403; KDP-3344-2024; AAG-6424-2021; EWU-3698-2022; AAH-7633-2021The purpose of this study was to determine the suitability of supplementing turmeric and/or mahaleb powders in crackers to enhance phenolic content and antioxidant activity. They replaced wheat flour for 0, 5.0, or 7.5%. The highest bioaccessible phenolics (7,591.90 mg of gallic acid equivalents/100 g dry weight) and phenolic bioaccessibility values (77.94%) were obtained in the 7.5M7.5T sample. Turmeric and/or mahaleb powders' addition had a positive effect on phenolic contents and bioaccessibilities of the cracker samples. In all assays, antioxidant capacities of the crackers supplemented with turmeric and/or mahaleb powders were significantly (P <= 0.05) higher than the control crackers. The results showed that the samples with turmeric and/or mahaleb powders exhibited significantly (P <= 0.05) higher bioaccessible antioxidants than the control sample. Bioaccessibilities of crackers based on antioxidant capacity increased linearly with supplementation increments. Antioxidant bioaccessibility of the crackers ranged between 9.00 to 47.29% for the TEAC(ABTS), 11.54 to 14.47% for the TEAC(CUPRAC) and 12.47 to 20.59% for the TEAC(DPPH). The highest antioxidant bioaccessibilities (47.29%, 14.47%, and 20.59%) in all assays (respectively ABTS, CUPRAC, and DPPH) were obtained in the 7.5M7.5T sample. According to sensorial evaluations, generally, all supplemented crackers scored higher than the control. The taste of the crackers improved by supplementation of turmeric and/or mahaleb powders, as these crackers had typical pleasant mahaleb and turmeric flavour. Overall results suggest that turmeric and mahaleb powders are functional food additives with high phenolic content, bioaccessibility and antioxidant capacity. They can be used in foods, especially in bakery products, without any adverse effect on sensory properties.Publication Effects of chia seed on chemical properties and quality characteristics of regular and low-fat crackers(Soc Brasileira Ciencia Tecnologia Alimentos, 2021-10-01) Dundar, Ayse Neslihan; Aydin, Emine; Yildiz, Elif; YILDIZ, ELİF; Parlak, Ozen; Ziraat Fakültesi; Gıda Mühendisliği Bölümü; 0000-0003-2084-7076; 0000-0003-1356-9012; 0000-0002-6858-9638; KEJ-5004-2024; AAG-6424-2021; AAA-3876-2022As a direct consequence of understanding the importance of the relationship between health and food, the interest in healthy recipes has increased. In the present study, wheat flour was used to replace chia seed (CS) in the cracker formulation (control) at levels of 10, 20, and 30% (w/w) and fat content was reduced by 25, 50, and 75% for the production of low-fat crackers. The physicochemical, textural, sensorial properties of the crackers were investigated. It was determined that CS had high a dietary fiber (38.7%), protein (21.78%), and fat (28.69%) content. The cracker sample containing 25% fat and 30% chia seed had the highest amounts of protein (14.49%) and dietary fiber (16.70%). CS could provide positive effects on health in terms of its high fiber content and low carbohydrate value. Six different fatty acids (FAs) were determined in the cracker samples. By reducing fat and increasing chia seed amount; oleic, linoleic, alpha-linolenic increased compared to the control sample, whereas the palmitic acid amount decreased significantly. According to the sensorial evaluation, the crackers were acceptable. It was also determined that CS was a suitable supplementation for low-fat products.