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BİLĞİÇ ALKAYA, DİLEK

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BİLĞİÇ ALKAYA

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DİLEK

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2016 - 20193
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End date: 2019 × Has files: true ×

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    Determination of Natamycin in Turkish Yoghurt
    (HINDAWI LTD, 2016) BİLĞİÇ ALKAYA, DİLEK; Alkaya, Dilek Bilgic; Karalomlu, Ozlem
    This study was aimed at developing RP-HPLC method for determination of natamycin in Turkish yoghurt. Chromatographic separation was achieved on a C8 column (150mm x 4.6mm x 5 mu m) with a mobile phase of methanol : water : acetic acid (12 : 8 : 1 v/v/v), at 1 mL/min flow rate with a detection of 303 nm. Natamycin was spiked into handmade yoghurt samples and used for validation. The method has been fully validated according to ISO 9233-2, 2007 (IDF 140-2, 2007). It was successfully applied to determination of 28 different Turkish yoghurt products. Findings dealing with the presence of natamycin in cheese samples are presented.
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    PublicationOpen Access
    Influence of extraction method on antioxidant properties of Rheum ribes root extract
    (OVIDIUS UNIV PRESS, 2019-01-01) BİLĞİÇ ALKAYA, DİLEK; Bilgic Alkaya, Dilek; Ayaz Seyhan, Serap; Ozturk, Busra Nagihan
    Rheum species are important medicinal herbs, often used in pharmacological research, due to the presence of anthracene derivatives in the subterranean parts of the plant. In this study, we intended to assess its antioxidant capacity, in correlation with the method of extraction. For this purpose, Rheum ribes extraction was realized with four solvents of different polarities (50% methanol, 70% ethanol, 80% acetonitrile, and petroleum ether). We used different extraction techniques, such as orbital shaker, ultrasonic stirrer, microwave, and Soxhlet extraction, and the total phenolic content of the Rheum ribes extracts was determined by modified Folin-Ciocalteu method. The reducing power and radical scavenging activity of the extracts were also evaluated. The results shown that the antioxidant activity of the extracts depends on the extraction methods especially through the used solvent and decreases in the order: ethanol > methanol > acetonitrile > petroleum ether.
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    PublicationOpen Access
    Development and Validation of Liquid Chromatographic Method with DAD for the Quantification of Natamycin In Dairy Products
    (MARMARA UNIV, FAC PHARMACY, 2017-04-01) BİLĞİÇ ALKAYA, DİLEK; Karalomlu, Ozlem; Alkaya, Dilek Bilgic
    In this paper high performance liquid chromatography method was developed for the determination of natamycin in dairy product in Turkish market. Chromatographic separation was achieved on a C8 column (150 mm x 4.6 mm x 5 mu m 100 mm) with a mobile phase of methanol : water : acetic acid (12:8:1 v/v/v), at 1ml/min flow rate with DAD detection at 303 nm. Natamycin was analysed simultaneously using HPLC-UV method of ISO 9233+2, 2007(IDF 140-2, 2007). The method was found linear over the concentration ranges of 0.01-0.8 mg/L. Correlation coefficients (r) of the regression equations were greater than 0.999. The LOD and LOQ values for UV and DAD were found 0.321 mg/kg and 0.355 mg/kg; 0.321 mg/kg and 0.388 mg/kg for cheese samples respectively. The relative recoveries obtained for the spiked cheese samples were between 90 and 110 %. Also the interday precision of the method was found as 1.874% and 3.442 % RSD values for UV and DAD dedections. From the results of the present study using HPLC-DAD indicated that it is not reasonable to attribute the determination of natamycin in cheese. Therefore, the difference of the validation parameters were found insignificant for both detections. However, It was succesfully applied to determination of 46 different cheese products and finding dealing with the presence of natamycin in cheese samples were presented.