Food Engineering / Gıda Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/12

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Subject: search.filters.subject.Rheology

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  • Article
    Citation - WoS: 12
    Effects of Fat Reduction on the Stability, Microstructure, Rheological and Color Characteristics of White-Brined Cheese Emulsion With Different Emulsifying Salt Amounts
    (Korean Society for Food Science of Animal Resources, 2018) Urgu, Müge; Ünlütürk, Sevcan; Koca, Nurcan
    Cheese emulsion is an intermediate product for the production of cheese powder and needs to be stable, homogeneous and pumpable characteristics to convey to the spray drier. This study was conducted to evaluate the effects of fat reduction and emulsifying salt (ES) amount in cheese emulsion systems on the physicochemical characteristics. Reduced-fat (RF) and full-fat (FF) white-brined cheese emulsions were produced with different dry matters (DM; 15%-25% excluding ES) and ES concentrations (0%-3% based on cheese weight). Stable cheese emulsion was obtained at lower DM in RF cheese emulsion than that of FF cheese emulsion. Reduction in the amount of ES resulted in instability of both emulsions. Apparent viscosity with pseudoplastic flow behavior significantly increased with the decrease of fat content in stable cheese emulsions. Microstructure of emulsions appeared to be related to the fat content, stability and degree of emulsification. Reduction of fat content caused to get less lightness and more greenness in color, whereas yellowness was significantly decreased by increase in the amount of ES. In conclusion, fat reduction resulted in higher viscosities of cheese emulsion due to inducing the increment of protein, and the addition amount of ES considered as very important factor to produce stable cheese emulsion without protein precipitation or cream separation. Therefore, for preparation of RF cheese emulsion using a variety of white-brined cheese, lower amounts of DM would be suggested in this study to obtain homogenous droplets in the atomizing process of spray drying.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 25
    Milk Fat Substitution by Microparticulated Protein in Reduced-Fat Cheese Emulsion: the Effects on Stability, Microstructure, Rheological and Sensory Properties
    (Korean Society for Food Science of Animal Resources, 2019) Urgu, Müge; Türk, Aylin; Ünlütürk, Sevcan; Kaymak Ertekin, Figen; Koca, Nurcan
    Fat reduction in the formulation of cheese emulsion causes problems in its flowability and functional characteristics during spray-dried cheese powder production. In order to eliminate these problems, the potential of using microparticulated whey protein (MWP) in cheese emulsions was examined in this study. Reduced-fat whitebrined cheese emulsions (RF) with different dry-matters (DM) (15%, 20%, and 25% excluding emulsifying salt) were produced using various MWP concentrations (0%-20% based on cheese DM of emulsion). Their key characteristics were compared to full-fat cheese emulsion (FF). MWP addition had no influence on prevention of the phase separation observed in the instable group (RF 15). The most notable effect of using MWP was a reduction in apparent viscosity of RF which significantly increased by fat reduction. Moreover, increasing the amount of MWP led to a decrease in the values of consistency index and an increase in the values of flow behavior index. On the other hand, using high amounts of MWP made the emulsion more liquid-like compared to full-fat counterpart. MWP utilization also resulted in similar lightness and yellowness parameters in RF as their full-fat counterparts. MWP in RF increased glossiness and flowability scores, while decreased mouth coating scores in sensory analyses. Fat reduction caused a more compact network, while a porous structure similar to FF was observed with MWP addition to RF. In conclusion, MWP showed a good potential for formulation of reducedfat cheese emulsions with rheological and sensorial characteristics suitable to be used as the feeding liquid in the spray drying process.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Effect of Different Raw Materials on Aroma Fingerprints of 'boza Using an E-Nose and Sensory Analysis
    (Wageningen Academic Publishers, 2019) Kemahlıoğlu, Kemal; Kendirci, Perihan; Kadiroğlu, Pınar; Yücel, Ufuk; Korel, Figen
    Boza is a Turkish traditional beverage produced by fermentation of maize, rice, wheat, millet, cracked wheat, and durum clear flour. The aim of this study was to determine the effect of different raw material combinations on the aroma fingerprints of boza samples using an electronic nose equipped with surface acoustic wave detector in combination with sensory analysis. According to flavour profile analysis of boza samples, significant differences were obtained among the samples. Hierarchical clustering analysis of e-nose and sensory analyses indicated that boza samples were clustered based on their aroma profiles, odour and taste properties revealing the effect of different cereals as raw materials. Rheological analysis showed that all boza samples exhibited pseudoplastic flow behaviour as the apparent viscosity decreased with increasing shear rate. This revealed that differences in raw materials did not change flow behaviour of boza samples. The results indicated that e-nose could be used as a fast and non-destructive method to assess the influence of raw material formulation on aroma profiles of boza samples in correlation with sensory analysis.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 21
    An innovative approach: Cow/oat milk based kefir
    (Hrvatska Mljekarska Udruga, 2015) Dinkçi, Nayil; Kesenkaş, Harun; Korel, Figen; Kınık, Özer
    The aim of this study was to evaluate the potential of kefir production using cow-oat milk mixture. Therefore kefir samples with 20, 40 and 60 % of oat milk were produced. The effect of oat-milk ratio on physicochemical, rheological, microbiological and sensory characteristics of the kefir samples was studied during 21 days storage at refrigerated conditions. Increasing oat milk concentration affected the whey-off and apparent viscosity by higher whey off and lower viscosity results. Also the proteolytic activity of the samples was decreased by raising the oat milk concentrations. Increase of the oat milk concentration leaded to a decrease of pH of the samples. Statistical analysis showed that the lactococci and lactobacilli viable cell counts differed among the samples while the highest count was detected in sample with the highest amount of oat milk. The control sample (without oat milk) had higher yeast count during the storage period. The final product with 20 % of oat-milk and without addition of flavour was found to be the most acceptable by the sensory panellists. The results indicate the possibility for a new cow/oat milk based kefir.
  • Article
    Citation - WoS: 33
    Citation - Scopus: 37
    Relationship Between Morphology, Rheology and Polygalacturonase Production by Aspergillus Sojae Atcc 20235 in Submerged Cultures
    (Elsevier Ltd., 2006) Göğüş, Nihan; Tarı, Canan; Öncü, Şelale; Ünlütürk, Sevcan; Tokatlı, Figen
    A full factorial statistical design, with the factors of, two taxonomically different strains, seven types of seed culture formulations (slants) and two types of fermentation media were used to investigate the effect of these parameters on the morphology and polygalacturonase production. The rheology of the final fermentation medium was analyzed and appropriate mathematical model was applied to calculate suspension viscosity. It was found that most fermentation broths showed non-Newtonian flow behavior. According to statistical analysis, factors of strain types and fermentation media and the interaction between them were found significant on the enzyme activity. The effect of seed culture formulations (slants) were found insignificant at the significance level of 1%. Interaction of slants with strain types and fermentation media were also found insignificant. Considering the morphology of the final culture, Aspergillus sojae with the desired pellet morphology in a complex media, inoculated with a seed culture prepared from molasses resulted in maximum polygalacturonase enzyme activity (0.2 U/ml) and lowest suspension viscosity with a broth rheology close to Newtonian flow behavior.