Okur, İlhami
The main scope of this dissertation was to investigate the effects of High Hydrostatic Pressure-Assisted Extraction (HHPE) on phenolic compounds from different food wastes. The other aim of this study was to compare HHPE with conventional solvent extraction (CSE). At this study, three different food wastes namely spent coffee ground (SCG), olive leaves and olive pomace were used. In the first part of the study, the effect of HHPE on the spent coffee ground was examined. Three different pressure levels (300,400 and 500 MPa) for 5,10 and 15 min at 25 ºC was used. HHPE treatment at 500 MPa for 15 min gave the highest TPC (11.96±0.11 mg GAE/g DW). Also, it was observed that pressure and time had a significant effect on TPC (p≤0.05). In the second part of the study, the optimum HHPE condition for the recovery of bioactive compounds from olive leaves was investigated. For the optimization study, a Box–Behnken design (BBD) with 3 variables was used. The independent HHPE parameters were chosen as the pressure (X1), time (X2) and solid to solvent ratio (X3). Like spent coffee ground, the pressure parameter was selected as 300 and 500 MPa. The treatment time was between 5 and 15 min. Solid to solvent ratio was chosen as 0.1-0.3 (w/v). Extraction temperature and ethanol-water solution were constant in this research and they were 25°C and 70% respectively. Optimum HHPE condition was selected as 433.33 MPa for 15 min with 0.1 w/v solid-solvent ratio to obtain maximum total phenolic (57.5 mg GAE/g DW) and oleuropein content (18.45 mg/g DW). In the third part of the study, like olive leaves, an optimization study was conducted for olive pomace. a Box–Behnken design (BBD) with 3 variables was used. The independent HHPE parameters were chosen as the pressure (X1), time (X2) and solvent concentration (X3). The pressure and time parameters were the same with spent coffee ground and olive leaves. The solvent concentration was chosen as 50-90%. The best HHPE condition for recovery phenolic compounds from olive pomace with the highest total phenolic (16.39 g GAE/ g DW) oleuropein content (45.90 mg/ 100 g DW) was found as 409 MPa for 11.16 min with 63.74% v/v ethanol concentration. In all three studies, it was observed that HHPE increased the phenolic content significantly compared to CSE (p≤0.05). In addition, based on FTIR results, there was no significant difference on the chemical structure of phenolic compounds by HHPE. HHPE increased individual phenolic compounds identified by HPLC significantly and this result was also supported by FTIR results according to bands corresponding to oleuropein, chlorogenic acid and caffeic acids. According to SEM results, HHPE treatment increased the contact area between sample and solvent compared to CSE. As a result, it could be said that the mass transfer rate of phenolic compounds was raised when HHPE treatment was performed. Overall, HHPE has a good potential to be used as a recovery method of phenolic compounds from waste material such as spent coffee ground, olive leaves and pomace based on reduction of treatment time temperature.


Improving the Recovery of Phenolic Compounds from Spent Coffee Grounds (SCG) by Environmentally Friendly Extraction Techniques
Okur, İlhami; Söyler, Ulviye Betül; Öztop, Halil Mecit; Alpas, Hami (MDPI AG, 2021-1-25)
The aim of this study was to investigate and compare the effects of different extraction techniques (high hydrostatic pressure-assisted extraction (HHPE), ultrasound-assisted extraction (UAE), and classical solvent extraction (CSE)) on phenolic compounds from spent coffee grounds (SCG). Different HHPE parameters (300, 400 and 500 MPa at 25 °C for 5, 10 and 15 min) and UAE parameters (40%, 50%, and 60% amplitude at 25 °C for 5, 10 and 15 min) were used. These techniques were compared with CSE (at 50 °C for 3...
Optimization and Comparison of High-Pressure-Assisted Extraction of Phenolic Compounds from Olive Pomace
Okur, İlhami; Öztop, Halil Mecit; Alpas, Hami (2022-12-16)
In this study, it was aimed to find the optimum condition for extraction of phenolic compounds from olive pomace by using high-pressure-assisted extraction (HPAE). In this method, different pressure parameters (300-500 MPa), times (5-15 min), and ethanol concentrations (50-90% v/v) were used. According to Box-Behnken design, 15 experimental runs were performed to find the optimum condition of total phenolic and oleuropein contents. Also, the optimum HPAE condition was compared with that of classical solvent...
High hydrostatic pressure assisted extraction of pectin from sugar beet pulp
Kaya, Burcu; Okur, İlhami; Alpas, Hami; Oztop, Mecit Halil (2021-05-01)
This study aimed to investigate the effect of high hydrostatic pressure assisted extraction (HHPE) (250, 350 and 450 MPa at 40 degrees C for 5 min with/without acid addition) of pectin from sugar beet pulp and compare its properties with pectin obtained from conventional extraction (CE). Degree of esterification (DE), galacturonic acid (Gal-A) content, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) relaxometry experiments were performed on the obtained pectin powder. HHP...
The effects of hydrogen peroxide, gallic acid and resveratrol on growth and catalase production of aspergillus fumigatus
Doğan, Tunca; Ögel, Zümrüt Begüm; Department of Food Engineering (2008)
The aim of this study was to analyze the effect of hydrogen peroxide and selected phenolic compounds on growth and catalase production of Aspergillus fumigatus. As a result of growing A. fumigatus at different temperatures it was observed that, growth and catalase production of this species were highest at 37 °C. Catalase production was highest in the presence of 1 mM H2O2, yielding a significant 3 fold increase with respect to the control. Biomass was also increased by 1,44 fold with respect to the control...
Degradation of decabromodiphenyl ether (BDE-209) in microcosms mimicking sediment environment subjected to comparative bioremediation strategies
Demirtepe, Hale; İmamoğlu, İpek (Elsevier BV, 2019-03-01)
The aim of this study was to examine bioremediation strategies for BDE-209 contaminated sediments. Sediment microcosms were established to observe anaerobic debromination of BDE-209 under conditions representing three bioremediadon strategies: biostimulation, bioaugmentation and natural attenuation. To simulate biostimulation, a defined mineral medium containing both a carbon source (sodium formate) and electron donor (ethanol) was added into sediments. Bioaugmentation was established by enrichment of the s...
Citation Formats