Browsing by Author "Gul, O."

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Effect of high-pressure homogenization pretreatment on gelation behavior and physicochemical, rheological and structural properties of sesame protein isolate with glucono-δ-lactone
(Elsevier B.V., 2024) Maribao, I.P.; Gul, O.
This study investigated the gelation of sesame protein isolate induced by high-pressure homogenization (HPH) with glucono-δ-lactone (GDL) acidification, focusing on the effect of pressures on gelation behavior and physicochemical, rheological and microstructural properties of the resulting gels. The HPH significantly affected the acidification kinetic parameters such as Vmax, Tmax, T5, and T4.5. The maximum Vmax (0.062 pH units/min) value was determined in the sample treated with 100 MPa, and T4.5 was decreased by 30 min with HPH at 50 and 100 MPa pressures. The particle size of sesame protein decreased with the homogenization pressure increased, and this played a role in the formation of lower particle size aggregates after gelation. The highest water holding capacity (69.02%) and gel strength (7.9 g) were reached with a pressure at 100 and 150 MPa, respectively. While a significant increase in the whiteness index of gels was observed by increasing pressure up to 100 MPa, the highest total color difference (ΔE) was detected at 50 MPa. The G′ value of the samples tended to increase with gelation time and with the high pressure applied, indicating a significant improvement in the elasticity of the gels. All gel samples exhibit shear-thinning behavior. Hydrophobic interactions were dominant in the gel samples, and the highest value (8.28 mg/g) was determined in the sample prehomogenized at 100 MPa. This study revealed that the gelation properties of sesame protein induced by GDL can be improved with HPH and that 100 MPa pressure application is ideal.
Effect of sesame protein isolate modified by high-pressure homogenization, high-intensity ultrasound, and high-pressure processing on the colloidal stability of sesame paste: Determination of physicochemical, rheological, microstructural properties and storage stability
(2024.01.01) Gul, O.; Sahin, M.S.; Saricaoglu, F.T.; Atalar, I.
In this study, sesame protein isolate modified with different emerging technologies, including high-pressure homogenization, high-intensity ultrasonication, and high-hydrostatic pressure, was applied to improve the stability of sesame paste. Sesame protein addition reduced the phase separation by up to 48% in sesame paste compared to the sample (control) without protein addition, and also significantly enhanced the firmness and spreadability. With the addition of sesame protein isolate, the sesame paste samples formed a denser and more compact appearance. The flow characteristics of samples were better fitted by the Herschel-Bulkley equation, and modifying the added protein also played an essential role in improving the flow properties of sesame paste samples. Phase separation and oxidative stability of sesame paste were significantly improved by the addition of modified protein. Overall, the results indicated that sesame protein modified with HPH technology has a significant potential to improve the quality of sesame paste and prevent phase separation.
Modifications to structural, techno-functional and rheological properties of sesame protein isolate by high pressure homogenization
(Elsevier B.V., 2023.01.01) Baskinci, T.; Gul, O.
In this study, we aimed to determine the effect of high pressure homogenization (HPH) at a pressure up to 150 MPa on microstructural, techno-functional and rheological properties of sesame protein isolate (SPI). HPH treatment caused a partial change in the secondary structure of SPI, however, the changes in surface hydrophobicity and free -SH groups, indicating HPH had significant effect on the tertiary structure. After the HPH treatment, the particles dispersed homogeneously with more rougher surface. Sesame proteins had the smallest particle size (0.79 mu m) and highest zeta potential (38.83 mV) at 100 MPa pressure. The most developed water/oil holding capacity, emulsification and foaming properties were achieved at 100 MPa pressure. However, the maximum stable foam formation (83.33 %) was determined at 150 MPa pressure. When the shear rate is fixed as 50 1/s, an increase in the viscosity value of the samples treated with 100 and 150 MPa pressure was detected compared to the control sample, while the lowest viscosity was determined the ones treated at 50 MPa. In all samples except 50 MPa pressure-treated proteins, viscoelastic character became dominant with increasing frequency (G' > G"). Modification with HPH resulted in a decrease of about 15 degrees C in the gelation temperature of SPI.