Browsing by Author "Saricaoglu F.T."

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Effect of high pressure homogenization on microstructure and rheological properties of hazelnut beverage cold-set gels induced glucono-δ-lactone
(2021-05-01) Gul O.; Saricaoglu F.T.; Atalar I.
In this study, high pressure homogenized (HPH) hazelnut beverage samples were acidified with glucono-δ-lactone (GDL) and rheological, structural and gel strength properties of the cold-set gels were characterized. Hazelnut beverage at a concentration of 10 g 100 mL−1 was treated with HPH up to 150 MPa pressure and then mixed with GDL (2 g 100 mL−1). Gelation of hazelnut beverages was observed with small deformation oscillatory measurements during 150 min. Hazelnut beverages acidified with GDL displayed shear thinning behavior due to decreasing viscosity with increasing shear rate, however, HPH led to an increase in apparent viscosities of cold set hazelnut beverage gels. Cold set hazelnut beverages were characterized as weak gel-like macromolecular dispersions due to storage modulus (G′) was higher than loss modulus (G″). Angular frequency dependence of complex modulus (G*) was studied to measure the strength of the cross-linking protein network of suspension systems by calculating a constant order of relaxation function (α) and concentration-dependent stiffness parameter (Aα). This study revealed for the first time that hazelnut proteins can form good gel structures with acidification, and gel properties can be improved by HPH treatment.
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
(2024-08-01) Gul O.; Sahin M.S.; Saricaoglu F.T.; Atalar I.
Effect of ultrasonication treatment on structural, physicochemical and bioactive properties of pasteurized rosehip (Rosa canina L.) nectar
(2020-01-01) Atalar I.; Saricaoglu F.T.; Odabas H.I.; Yilmaz V.A.; Gul O.
The effect of ultrasonication process (US) on the physical and bioactive properties of pasteurized rosehip nectar was investigated. In order to solve sedimentation problem, two amplitude levels (50 and 100%) and different treatment times (5, 10, 15 and 30 min) were applied to rosehip nectars. Mean particle size decreased as amplitude and treatment time increased. US treatment caused to increase in redness and yellowness values of nectars and also color change was found noticeable as 1.9–2.6 at 100% amplitudes. US treated samples showed no sedimentation during storage for 15 days while control sample displayed 74% colloidal stability. All samples showed shear-thinning behavior and were characterized as weak gel network. Total phenolic and carotenoid contents and antioxidant activity was increased by US treatment, however, ascorbic acid content decreased. US treatment can be an alternative technology preventing sedimentation problems during shelf life with minimally affecting bioactive and physical properties of rosehip nectar.
Influence of pH and ionic strength on the bulk and interfacial rheology and technofunctional properties of hazelnut meal protein isolate
(2023-07-01) Gul O.; Gul L.B.; Baskıncı T.; Parlak M.E.; Saricaoglu F.T.
The functional, bulk, and interfacial shear rheological properties of hazelnut protein isolate were studied at different pH values between 3.0 and 8.0 and ionic strength levels between 0.0 and 1.0 M. The results showed that pH significantly affected protein solubility, emulsion properties, water and oil holding capacities, foam stability, surface hydrophobicity, and free -SH groups. The highest surface hydrophobicity, free -SH groups, and better functional properties were observed at pH 8.0. Protein solubility also increased with increasing ionic strength up to 0.6 M. The emulsion and foam stability of hazelnut protein isolate showed similar changes with protein solubility. The flow behavior of hazelnut protein suspensions was found to be shear thinning with the highest consistency index at pH 3.0 and the lowest at pH 6.0, however, the ionic strength did not significantly affect the consistency coefficient but did cause a significant change in the flow behavior index, with the lowest value observed at 0.6 M. The best gel structure in hazelnut proteins was observed at pH 3.0 and 4.0. The addition of ions at 0.4 and 0.6 M concentrations resulted in an improved viscoelastic character. The hazelnut protein isolate was also found to form solid-like viscoelastic layers at both air-water and oil-water interfaces, with the interfacial adsorption behavior affected by both pH and ionic strength. Overall, these results suggest that pH and ionic strength have significant effects on the functional and rheological properties of hazelnut protein isolate, which may have the potential as an auxiliary substance in food systems.
Potential Use of High Pressure Homogenized Hazelnut Beverage for a Functional Yoghurt-Like Product
(2022-01-01) Gul O.; Atalar I.; Mortas M.; Saricaoglu F.T.; Besir A.; Gul L.B.; Yazici F.
Hazelnut beverage is a plant-based beverage produced from hazelnut cake as a by-product obtained after cold press extraction. It has high nutritional value and a significant percentage of consumers show interest in it due to its health benefits. In this study, hazelnut beverage manufactured from by-products of hazelnut oil industry was incorporated into functional yoghurt production. Five formulations (ratio of 1/0, 3/1, 2/1, 1/1, 0/1, v/v, cow milk/hazelnut beverage) of yoghurt-like products were prepared to indicate the storage period of the samples and the analysis performed. For yoghurt production, hazelnut beverage and cows' milk were standardized to 14.5 g 100 g -1 with skimmed milk powder. The use of hazelnut beverage in yoghurt production negatively affected L. bulgaricus counts. Water holding capacity and viscosity values were improved by using hazelnut beverage. Increasing hazelnut beverage concentration led to an increase in the total phenolic compounds and antioxidant activity, malic acid levels and also unsaturated fatty acids, especially oleic and linoleic acid. Using the ratio of 3/1 was found the best in view of appearance, flavor and overall acceptability. Based on the structural, rheological and sensorial properties, this study could guide the dairy industry to use hazelnut beverage obtained from hazelnut cake.
Structural Characterization, Technofunctional and Rheological Properties of Sesame Proteins Treated by High-Intensity Ultrasound
(2023-05-01) Gul O.; Saricaoglu F.T.; Atalar I.; Gul L.B.; Tornuk F.; Simsek S.
Plant-derived proteins, such as those from sesame seeds, have the potential to be used as versatile food ingredients. End-use functionality can be further improved by high-intensity ultrasound treatments. The effects of high-intensity ultrasound on the properties of sesame protein isolates from cold-pressed sesame cake were evaluated. The SDS-PAGE demonstrated no significant changes in the molecular weight of proteins. Ultrasound treatments resulted in decreased particle size with a more uniform distribution, resulting in the exposure of hydrophobicity and free −SH groups and increased zeta potential. Although FTIR spectra of proteins were similar after ultrasonication, a partial increase in the intensity of the amide A band was observed. The ultrasound significantly (p < 0.05) affected the secondary structure of proteins. While optical micrographics revealed a dispersed structure with smaller particles after treatments, microstructural observations indicated more rough and irregular surfaces. Water solubility was improved to 80.73% in the sample subjected to 6 min of ultrasonication. Sesame protein solutions treated for 4 and 6 min exhibited viscoelastic structure (storage modulus (G′) > loss modulus (G′′)). In addition, the gelation temperature of proteins decreased to about 60–65 °C with increasing treatment time. Overall, ultrasound is a useful technique for the modification of sesame protein isolates.