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    A modeling approach in the interpretation of starch pasting properties
    (Academic Press Ltd- Elsevier Science Ltd, 2017) Palabıyık, İbrahim; Toker, Ömer Said; Karaman, Safa; Yıldız, Önder
    In this work, starch pasting curves were reinterpreted with suitable models to show deficiency of widely used starch pasting parameters in the literature. The aim was to attract scientific attentions to the behavior and dynamics of the curve with respect to process parameters instead of values on the curve. Mainly, pasting curve was separated into four parts combining sigmoidal gelatinization model, exponential thinning model and Arrhenius temperature model. For the gelatinization part, starch swelling rate, water binding capacity and starch resistivities to heat and shear might be compared by the proposed model parameters. Amylose and damaged starch contents of starches had a good relation with Arrhenius and exponential model parameters. Activation energy values gave clues about retrogradation rate of starches and changed between 7142 and 17,327 kJ/mol. (C) 2017 Elsevier Ltd. All rights reserved.
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    Optimization of citrus fiber-enriched vegan cream cheese alternative and its influence on chemical, physical, and sensory properties
    (Wiley, 2024) Gurbuz, Basak; Cayir, Merve; Akdeniz, Esra; Akyil Ozturk, Saniye; Karaman, Safa; Karimidastjerd, Atefeh; Toker, Omer Said
    Dairy product alternatives have increased in recent years as a result of medical prescriptions or personal preferences. The main purpose of the present study was to optimize vegan-based cream cheese formulation added with citrus fiber considering the textural and physicochemical properties of the samples. The physicochemical (pH value, water activity, and color), texture, microstructure, and sensory properties of manufactured vegan-based cream cheese were characterized and compared to those of a commercial one. Three optimized products were produced, according to the textural properties. The addition of citrus fiber did not affect the pH and water activity values of the cheese samples significantly. Although citrus fiber had an effect on the color values of the samples, a significant difference in the sensory scores was not recorded by the panelists. The sample having 1.21% citrus fiber (A) showed a hardness value similar to that of control sample and it received high sensory appreciation. The sample added with 1.41% citrus fiber (B) was scored high by the panelists, with no significant difference compared to commercial cream cheese, even though it showed high hardness. According to the results of the current research, vegan-based cream cheese can be produced as a promising food as a new alternative to milk and dairy products. The present study is carried out to optimize a vegan-based cream cheese product using pea protein and citrus fiber using mixture design approach. In the first stage, physicochemical and textural characteristics of the produced cheese samples were determined and the best receipt was created based on the textural analysis and in the second stage, three different cheese samples having different citrus fiber and fat levels were prepared and compared to those of a commercial vegan cream cheese sample.image
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    Pasting properties, texture profile and stress-relaxation behavior of wheat starch/dietary fiber systems
    (Elsevier Science Bv, 2013) Yıldız, Önder; Yurt, Bayram; Baştürk, Ayhan; Toker, Ömer Said; Yılmaz, Mustafa Tahsin; Karaman, Safa; Dağlıoğlu, Orhan
    The effect of dietary fiber type (oat, pea, lemon and apple) and concentration (0, 2.5, 5, 10, 15 and 20% w/w) on theological properties of wheat starch/fiber systems was evaluated based on their pasting properties; texture profile and stress-relaxation behavior. Peak, trough, breakdown, final and setback viscosity increased; however, peak time and pasting temperature decreased as fiber concentration increased. The lemon fiber was the most effective in increasing the pasting viscosity parameters, and in decreasing pasting temperature, followed by apple, pea and oat fibers. The effect of fiber concentration was successfully described by power-law and exponential type models; however, estimating the performance of exponential model was generally better. Regarding texture profile, an increase in fiber concentration linearly decreased hardness, adhesiveness, gumminess and chewiness values of the starch/lemon fiber and starch/apple fiber gels. Maxwell, Nussinovitch and Peleg models were used to evaluate the stress relaxation data. Maxwell and Peleg models were the best in representing the stress relaxation behavior; however, Nussinovitch model was also valid. Fiber addition changed the stress relaxation properties, which was remarkable depending on fiber concentration. Fiber addition increased the elasticity of wheat starch gel. To summarize, fiber addition provided an increase in resistance of wheat starch gel to deformation, as revealed by the RVA, TPA and stress relaxation tests. (C) 2013 Elsevier Ltd. All rights reserved.
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    Recovery Potential of Cold Press Byproducts Obtained from the Edible Oil Industry: Physicochemical, Bioactive, and Antimicrobial Properties
    (Amer Chemical Soc, 2015) Karaman, Safa; Karasu, Salih; Tornuk, Fatih; Toker, Ömer Said; Geçgel, Ümit; Sağdıç, Osman; Gül, Osman
    Physicochemical, bioactive, and antimicrobial properties of different cold press edible oil byproducts (almond (AOB), walnut (WOB), pomegranate (POB), and grape (GOB)) were investigated. Oil, protein, and crude fiber content of the byproducts were found between 4.82 and 12.57%, between 9.38 and 49.05%, and between 5.87 and 45.83%, respectively. GOB had very high crude fiber content; therefore, it may have potential for use as a new dietary fiber source in the food industry. As GOB, POB, and WOB oils were rich in polyunsaturated fatty acids, AOB was rich in monounsaturated fatty acids. Oil byproducts were also found to be rich in dietary mineral contents, especially potassium, calcium, phosphorus, and magnesium. WOB had highest total phenolic (802 ppm), flavonoid (216 ppm), and total hydrolyzed tannin (2185 ppm) contents among the other byproducts. Volatile compounds of all the byproducts are mainly composed of terpenes in concentration of approximately 95%. Limonene was the dominant volatile compound in all of the byproducts. Almond and pomegranate byproduct extracts showed antibacterial activity depending on their concentration, whereas those of walnut and grape byproducts showed no antibacterial activity against any pathogenic bacteria tested. According to the results of the present study, walnut, almond, pomegranate, and grape seed oil byproducts possess valuable properties that can be taken into consideration for improvement of nutritional and functional properties of many food products.
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    Rheological and some Physicochemical Properties of Selected Hydrocolloids and their Interactions with Guar Gum: Characterization using Principal Component Analysis and Viscous Synergism Index
    (Taylor & Francis Inc, 2014) Karaman, Safa; Kesler, Yusuf; Göksel, Meryem; Doğan, Mahmut; Kayacier, Ahmed
    In this study, rheological and some physicochemical characteristics of some commercial hydrocolloids were determined. Principal component analysis and viscous synergism index (I-v) were used for the characterization of gums. Specific gravity and pH values of hydrocolloids were in the range of 0.431-1.010 and 5.470-9.830, respectively. Power law model was used to describe the viscous flow behavior of hydrocolloids. In general, hydrocolloids exhibited significant differences in many physicochemical characteristics (p < 0.05). When used individually, xanthan gum showed the highest K (5.131 Pa s(n)) compared to others. The highest K value was calculated to be 11.570 Pa s(n) for xanthan and guar gum mixture, which shows a synergistic interaction (I-v = 0.866), while the lowest was for tara and guar gum mixture (0.212 Pa s(n)), which shows an antagonistic interaction (I-v = 0.459). The n values were in the range of 0.118-0.816 and 0.098-0.619 for sole and mixture hydrocolloids, respectively. Nine physiochemical and rheological variables were reduced to two independent principal components, which accounted for 88.42% of the total variance. Moisture, pH, water holding capacity, oil holding capacity, and ash resulted in the most effective variables for the PC1 while specific gravity, consistency coefficient, and flow behavior index were useful to define the PC2.