Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 24Citation - Scopus: 35Physicochemical and Rheological Properties of Rice-Based Gluten-Free Blends Containing Differently Treated Chickpea Flours(Academic Press Inc., 2018) Kahraman, Gökçen; Harsa, Şebnem; Lucisano, Mara; Cappa, CarolaThis study focused on the evaluation of the physicochemical and rheological properties of chickpea flours and blends obtained by partially substituting rice flour (25 g/100 g) with raw, roasted and dehulled chickpea flour. The characteristics of the resultant doughs were evaluated. In comparison with rice flour, blends containing chickpea flours exhibited high protein and fat content, a reduced retrogradation tendency (setback values of 404–415 vs. 479 Brabender Unit) and a higher foaming capacity and stability, which can be beneficial for their use in baked food formulations. However, roasting decreased foaming capacity and stability. Even if the rheofermentographic test evidenced a slight reduction in dough development, high CO2 retention capacity (≥ 98%) and similar-to-lower leavening times were observed for doughs containing chickpea flours. Incorporating chickpea flours also caused an increase in the viscous and elastic moduli of rice-based doughs, resulting in a good structuring of the dough. The results of this study indicated that chickpea flours could be used as a healthy ingredient in gluten-free rice-based formulations.Article Citation - WoS: 15Citation - Scopus: 19Whey Protein-Pullulan (wp/Pullulan) Polymer Blend for Preservation of Viability of Lactobacillus Acidophilus(Taylor and Francis Ltd., 2015) Çabuk, Burcu; Harsa, Hayriye Şebnem; Harsa, ŞebnemIn this study, whey protein isolate-pullulan (WP/pullulan) microspheres were developed to entrap the probiotic Lactobacillus acidophilus NRRL-B 4495 by spray-drying technique. Microcapsules were analyzed for physicochemical characteristics including morphology, particle size, moisture content, water activity, dissolution time, and color properties. Results revealed that microcapsules were spherical in shape and obtained particle sizes between 5 and 160 µm, with an average size of around 50 µm. Blending pullulan with WP provided enhanced survival of probiotic bacteria during spray drying with a final viable cell number of 8.81 log CFU/g of microcapsule. Encapsulated probiotics were also found to have significantly (p ≤ 0.05) higher survived cell numbers compared to free probiotics under detrimental gastrointestinal conditions. Moreover, dissolution analysis suggested that protein-polysaccharide powdered microcapsules showed pH-sensitive dissolution properties in simulated gastric juice and simulated intestinal juice.Article Citation - WoS: 34Citation - Scopus: 39High Genetic and Phenotypic Variability of Streptococcus Thermophilus Strains Isolated From Artisanal Yuruk Yoghurts(Academic Press Inc., 2014) Erkuş, Oylum; Okuklu, Burcu; Yenidünya, Ali Fazıl; Harsa, ŞebnemStreptococcus thermophilus is a commonly used starter bacterium in dairy industry. It reduces the pH of milk rapidly and equilibrates the medium for the growth of Lactobacillus delbrueckii subsp. bulgaricus during yoghurt fermentation. Efforts to increase the diversity of artisanal yoghurt starters are not only important to bring new strains with novel and desirable characteristics, but also for the preservation of natural diversity which diminishes with the overuse and spread of industrial starters to natural resources. In the present study, 14 artisanal yoghurt samples were processed for the isolation of promising strains for yoghurt starter culture production and 66 strains were subsequently characterized. They were all identified as S. thermophilus using species-specific PCR and 16S rRNA gene sequencing. Genotypic diversity at the strain level was investigated by pulsed field gel electrophoresis (PFGE), and 22 homology groups were obtained. Further phenotypic characterization unearthed a significant phenotypic heterogeneity within homology groups, mostly with atypical novel character. Only 7 out of 66 strains showed S. thermophilus type-strain like phenotypic traits. Majority of the isolates were determined to be protease positive and fast milk acidifier to be used as yoghurt starter culture.Article Citation - WoS: 48Citation - Scopus: 59Biochemical and Thermal Properties of Ss-Galactosidase Enzymes Produced by Artisanal Yoghurt Cultures(Elsevier Ltd., 2010) Üstok, Fatma Işık; Tarı, Canan; Harsa, Şebnemβ-Galactosidases, produced by pure and mixed cultures of Streptococcus thermophilus 95/2 (St 95/2) and Lactobacillus delbrueckii ssp bulgaricus 77 (Lb 77) isolated from the Toros mountain region of Turkey, were characterised with respect to their biochemical and thermal properties. Optimum pH and temperature for maximum activity were determined and these enzymes were stable in the pH range 7-9 and in the temperature range 20-37 °C, retaining 80-90% of their initial activities. The inactivation energies of β-galactosidase from Lb 77, St 95/2 and mixed culture (Lb 77 and St 95/2) were 51.3, 44.0 and 48.3 kcal mol-1, respectively. Moreover, thermodynamic (ΔG, ΔS, ΔH) and kinetic constants (Km and Vmax) were determined and effects of metal ions were investigated. As a result, these enzymes could be considered as potential candidates for lactose hydrolysis of milk and milk products. © 2009 Elsevier Ltd. All rights reserved.