Phd Degree / Doktora
Permanent URI for this collectionhttps://hdl.handle.net/11147/2869
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Doctoral Thesis Physiologic Effects of the Golden Thistle (scolymus Hispanicus L.) Hydromethanolic Extracts: Outcomes of Phytochemical Health Benefits(01. Izmir Institute of Technology, 2022) Özel Taşcı, Cansu; Güleç, Şükrü; Büyükkileci, Ali Oğuz; Güleç, Şükrü; Büyükkileci, Ali OğuzThis dissertation aimed to screen the beneficial health effects of a hydromethanolic extract (GTE) obtained from the golden thistle (S. hispanicus L.) on different health conditions, including type 2 diabetes, inflammation, cancer, and wound healing. First, 1 mg/mL GTE resulted in 6.94% chlorogenic acid (CGA) bioavailability with (1.82±0.07)x10-6 cm/s apparent permeability on differentiated CaCo-2 cells. Then, 1 mg/mL GTE prompted 39.4-42.6% less glucose efflux and 49-66% less GLUT2 mRNA expressions on CaCo-2 cells. In the systemic inflammation model, pre-treatments of 50-500 μg/mL GTE reduced some inflammatory markers after 0.5 μg/mL lipopolysaccharide (LPS) inflammation induction for 12 h on RAW 264.7 cells. Reductions in 30-53%, 32-45% and 16-36% ranges for nitric oxide, tumor necrosis factor-α, and interleukin-6 (IL-6) were determined, respectively. Additionally, same GTE concentrations were pre-treated with the CaCo-2 cells in the colonic inflammation model. 15.5-19.5% and 8.7-17.3% less IL-6 and IL-8 cytokine releases were detected from CaCo-2 cells, respectively. The wound healing model of 3T3-L1 mouse fibroblasts revealed that 40-80 μg/mL root bark extract resulted in enhanced wound closures with significant differences in the cell cycle distributions. As the most significant result, G2 phase distributions were 1.8% and 12.5% in the negative and positive control samples, respectively. The root bark extract treatments of 10, 40, and 80 μg/mL resulted in 6.6%, 7.1%, and 9.1% in increasing concentrations. Finally, 4 mg/mL GTE application to CaCo-2 human adenocarcinoma cells caused 78.4% reduced cell viability, a cell cycle arrest, and increased early and late apoptotic properties. Overall results suggest that S. hispanicus L. has functional molecules that influence cellular regulations and have potential beneficial health effects.Doctoral Thesis Bioactive Compound Retention and Shelf Life Extension of Strawberry Juice by Selected Nonthermal Processing Technologies(Izmir Institute of Technology, 2017) Yıldız, Semanur; Ünlütürk, Sevcan; Barbosa-Canovas, Gustavo V.Shelf life extension of fruit juices while maintaining quality and functional properties is of great interest. Nonthermal food processing technologies have been emerged as innovative preservation methods alternative to thermal pasteurization of fruit juices. The objectives of this Ph.D. thesis were to (i) ensure microbial safety of strawberry juice (SJ) by thermal and nonthermal technologies, i.e. high pressure processing (HPP), ultrasound (US), pulsed electric field (PEF) and UV-C irradiation; (ii) evaluate physicochemical and phytochemical properties of SJ after processing and during storage; (iii) extend microbial shelf life of SJ without unduly affecting quality. HPP (300 MPa, 1 min), US (120 m, 5.15 J/mL, 55 C, 3 min), PEF (35 kV/cm, 27 s, 155 Hz), and thermal pasteurization (71.7 C, 15 s) conditions were determined based on equivalent inactivation of E.coli (ATCC 11775) in SJ studied at Washington State University. UV-C irradiation (1.01 J/mL, 53.9 C, 6 cycles, 5.8 min) and thermal pasteurization (72 C, 101 s) conditions were determined considering inactivation of E. coli K-12 (ATCC 25253) in SJ studied at IZTECH. Consequently, microbial shelf life of SJ treated by HPP, thermosonication, UVC+mild heating, thermal pasteurization was extended up to 42 days while PEF prolonged up to 35 days at refrigerated storage. Multivariate data analysis revealed that HPP and PEF enhanced phytochemical characteristics of SJ compared to thermosonication and thermal pasteurization. Although UV-C irradiation did not alter physcicochemical properties, total phenolic content, and antioxidant activities of SJ, total anthocyanin content was significantly decreased by UV-C light compared to untreated juice.Doctoral Thesis Applications of Mid-Ir Spectroscopy for Identification of Wine and Olive Yeasts and Characterization of Antimicrobial Activities of Phenolics on Yeasts(Izmir Institute of Technology, 2015) Canal, Canan; Özen, Fatma Banu; Baysal, Ayşe HandanThe aim of this study was application of mid-IR spectroscopy in combination with multivariate statistical analysis for characterization of yeasts from two fermented products, wine and olive, in comparison with cultural and molecular tests and characterization of antimicrobial effects induced by olive phenolics on yeasts. Totally 19 wine yeasts were molecularly identified as M. pulcherrima (11%), P. membranifaciens (16%), H. uvarum (5%) and S. cerevisiae (68%). According to FTIR spectroscopic data of wine samples, S. cerevisiae isolates formed a cluster which were generally separated from all other yeasts. Totally 182 olive yeasts were identified from naturally debittered Hurma and a common olive variety and their leaves. The most common yeasts were Metschnikowia sp. (39%) and Aureobasidium sp (78%) in the first and the second harvest years, respectively. Since only Aureobasidium sp. was the common yeast isolated from Hurma during both years, any link between natural debittering of Hurma and the yeast population of this olive type might be related to Aureobasidium sp. Molecularly identified yeast types generally formed different clusters and showed spectral differences. For antimicrobial activity tests, all phenolic compounds were found effective on both S. cerevisiae and A. pullulans; however, A. pullulans was observed to be more sensitive. Antimicrobial activity was differentiated with respect to treatment time and phenol concentration with statistical treatment of FTIR data. As a complementary technique, FTIR could be successfully used for identification of yeasts and characterization of antimicrobial activity of phenolics against yeasts.