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Öğe Covalent immobilization of aspergillus niger amyloglucosidase (ANAG) with ethylenediamine-functionalized and glutaraldehyde-activated active carbon (EFGAAC) obtained from sesame seed shell(Elsevier, 2020) Sharif, Yousif Mohammed; Şahin, Ömer; Aslan, YakupThis study was aimed the covalently immobilization of Aspergillus niger amyloglucosidase (ANAG) onto activated carbon (AC) obtained from sesame seed shell. AC was firstly functionalized with ethylenediamine, and after then activated with glutaraldehyde. 99.80% immobilization yield and 99.83% activity yield were obtained as the result of optimization of immobilization conditions (pH and molarity of immobilization buffer, AC amount, and reaction time). The optimum pH (5.5) and the optimum temperature range (55–60 C) for ANAG were not affected by immobilization. After immobilization, Vmax value decreased from 1464.1 lmol D-glucose/L.min to 1342.3 lmol D-glucose/L.min, while Km value decreased from 116.3 g maltodextrin/L to 109.9 g maltodextrin/L. The immobilized enzyme retained 99.30% and 98.30% of its initial activity, respectively after twenty repeated uses and after twenty days of storage in 5 mL sodium phosphate buffer (0.1 M, pH 5.5) at +4 C in a refrigerator. Finally, glucose syrup was produced from maltodextrin solution having 1% (w/v) concentration by using the immobilized ANAG. Maltodextrin was completely converted to glucose after four hours. Consequently, it can be said that the immobilized ANAG obtained in this study can be used in the industrial production of glucose syrup.Öğe Incorporation of Defatted Apple Seeds in Chewing Gum System and Phloridzin Dissolution Kinetics(2019) Gunes, R.; Palabiyik, I.; Toker, O.S.; Kurultay, S.Apple seeds are among the major natural sources of antioxidants and can be used in various industries. In this regard, antioxidant activity, total phenolic content, and individual phenolic compounds analyzes of defatted apple seed flours were firstly done in our study. According to these analyzes, total phenolic content, DPPH and ABTS radical scavenging activity of defatted seed flours were determined between 2861 and 5141 mg GAE/kg defatted seed, 21.45–43.56 μmol, and 291.50–391.79 μmol Trolox/g defatted seed, respectively. It was observed that the content of phloridzin represented 52–67% and 75–83% of the total phenolics that measured by the Folin-Ciocalteu assay and HPLC method, respectively. In the second part, chewing gums including defatted seeds were prepared and characterized in terms of phloridzin dissolution. The novel model described dissolution kinetics of phloridzin from chewing gum better than Higuchi and Korsmeyer-Peppas models. The results de- monstrated that 5 min was enough for the dissolution of almost all phloridzin (88.43–96%) determined by centrifugation method and according to the model parameters, the chewing gum formulation can be optimized for providing controlled dissolution. In conclusion, chewing gum could be a suitable delivering material for phloridzin uptake, and apple seeds, a valuable agricultural by-product, could be evaluated in this way.Öğe Effect of Ball-Mill Process on Some Quality Parameters of Chcocolate and Compound Chocolate: A Modelling Approach(2019)The long processing time is among the reasons for low efficiency in the implementation of conventional conching and ball-mill techniques. In this study, the time-dependent vari- ation of the moisture, particle size, and water activity of dark, milk, white, and com- pound chocolate (cocolin) samples were modeled using polynomial regression analysis. For this aim, analyzes were performed in chocolate samples taken at 10-min intervals. The total processing time was 150 min. It was determined that the particle size, water activity, and moisture contents of all the samples decreased with time, but these decreases varied depending on the chocolate variety. Time- dependent particle size (D90), water activity (aw), and moisture variation models were modeled and R2 values were found in the range of .984–.996, .872–.988, and .805–.905, respectively. For all types of chocolate, the quadratic relationship for “time × particle size” and cubic relationship for “time × water activity” were deter- mined. For dark chocolate, the quadratic relationship was detected between time and moisture content. It was seen that this relationship was cubic for other types of chocolates. The results of the study reveal that the ball-mill technique is possible to be modeled successfully for the particle size change and moisture removal in the main chocolate varieties.Öğe Application of simplex lattice mixture design for optimization of sucrose-free milk chocolate produced in a ball mill(2019) Homayouni Rad, A.; Rasouli Pirouzian, H.; Toker, O.S.The aim of this study was to define optimal conditions by using Simplex lattice mixture design for the for- mulation of sucrose-free chocolate produced in a ball mill. Milk chocolate mass were made using three different polyols including maltitol, xylitol and isomalt along with Stevia as high potency sweetener. The influences of polyols mixtures as sucrose substitutes on rheological properties and main physical quality parameters were investigated. According to the results, the fitted models demonstrated a high coefficient of determination (≥93%). The optimization of the variables illustrated that utilizing 11.16% w/w maltitol, 8.9% w/w xylitol and 12.93% w/w isomalt produced the optimum milk chocolate with the highest desirability (1.00) without un- wanted variations in the rheological and quality characteristics. Also the optimum formulation was produced to validate the optimum model. The sensory analysis of the optimized formulation satisfied the consumer demand.Öğe Determination of Some Quality and Safety Parameters for Black Raisin Juice(April, 2019) Aslan, Yakup; Hussein, Hawsar Syamand; Abdullah, Seerwan Ahmed; Cavidoğlu, İsaThe aim of the present study was to determine the safety and the quality parameters of raisin juice, such as total soluble solids (TSS), pH, titratable acidity (TTA), kinds and quantity of sugars, phenolic acid compounds, polyphenoloxidase (PPO) enzyme activity, water activity and total microbial counts. The total soluble solids and pH values were significantly decreased after two weeks of storage, while the titratable acidity in most samples were slightly changed. Glucose, fructose and sucrose as well as three kinds of phenolic acids such as gallic, chlorogenic and vanilic acids were determined in all samples. Total microbial contents of the freshly prepared raisin juice and of the raisin juice stored for one and two weeks did not significantly changed. The water activity was slightly decreased, while the polyphenoloxidase activity was significantly decreased, after storage for two weeks. Consequently, it can be said that the freshly prepared raisin juice and the raisin juice stored for one week have superior sensorial properties than the raisin juice stored for two weeks.Öğe Covalent immobilization of an alkaline protease from Bacillus licheniformis(DeGruyter, Aralık, 2018) Aslan, Yakup; Ömerosmanoğlu, Derya; Koç, Eda ÖndülObjective: Since the soluble enzymes can not be used in repeated reactions and are not stable in operational conditions and not suitable for continuous processes, this study aimed the covalent immobilization of Bacillus licheniformis protease (BLP) onto Eupergit CM. Methods: Optimum conditions for immobilization were determined by changing the conditions individually. The proteins and L-tyrosine were determined by UV/VIS spectrophotometer. Results: The immobilization resulted in 100% immobilization and 107.7% activity yields. The optimum pH (7–8) and the optimum temperature (70°C) have not changed after immobilization. The Km values for free and immobilized enzyme were 26.53 and 37.59 g/L, while the Vmax values were 2.84 and 3.31 g L-Tyrosine/L · min, respectively. The immobilized enzyme has not lost its initial activity during the repeated 20 uses and 20 days of storage. The milk proteins were hydrolyzed in 2 h by using immobilized enzyme. The pH of the milk dropped from 6.89 to 6.53, the color was clearer but there was no change in the smell or the taste. Conclusion: Consequently, it can be said that the immobilized BLP obtained can be used for industrial purposes.Öğe Improved catalytic activity of aspergillus oryzae β-galactosidase by covalent immobilization on eupergit cm(Descember, 2018) Aslan, Yakup; Taher, Alan Yaseen; Cavidoğlu, İsaIn this study, Aspergillus oryzae β-Galactosidase (AOG) was immobilized onto Eupergit CM. By optimizing the immobilization conditions such as pH and molarity of immobilization buffer, enzyme/support ratio and duration of immobilization, 100.00% immobilization yield and 129.82% activity yield was achieved. The optimum temperature (55 °C) of free enzyme was not changed while optimum pH of free enzyme was shifted from 4.5 to 5.5 after immobilization. Kinetic constants for free and immobilized enzyme were also determined by using the Lineweaver-Burk plot. The Km values of the free and immobilized enzymes were determined to be 307.7 and 234.2 g / L respectively, while the Vmax values were determined to be 0.366 g D-Glucose / L.min and 0.415 g D-Glucose / L.min respectively. The operational and storage stabilities of immobilized enzyme were also studied. The activity of immobilized enzyme decreased to 99.3% after repeated twenty usage while decreased to 98.3% after fifteen days of storage. Further, the immobilized enzyme was used for the hydrolyzing the cow's milk lactose. By using the immobilized enzyme, the milk lactose was completely hydrolyzed in four hours. Consequently, immobilized AOG can be used in the industrial production of lactose-free cow's milk.Öğe IMMOBILIZATION OF Aspergillus oryzae β-GALACTOSIDASE TO PRODUCE LACTOSE-FREE MILK(January-2018) Cavidoğlu, İsaAspergillus oryzae β-galactosidase enzyme, in this thesis study, was immobilized onto Eupergit CM, using covalent binding method with 100 % immobilization yield and 129.82 % activity yield by optimizing the immobilization conditions. Characterization of free and immobilized Aspergillus oryzae β-Galactosidase was also studied. After immobilization, optimum pH shifted from 4.5 to 5.5, while the optimum temperature (55 ° C) did not change. For free and immobilized enzymes, kinetic constants were also determined by using the Lineweaver-Burk graph. The Km values of the free and immobilized enzymes were determined to be 307.7 and 234.2 g / L, respectively, while the Vmax values were determined to be 0.366 and 0.415 g D-Glucose / L.min respectively. There was no decrease in the initial activity of the immobilized enzyme after repeated 20 batch experiments and after storage for 15 days under optimum conditions. In addition, using the immobilized enzyme, the lactose in the semi-skimmed UHT cow's milk was completely hydrolyzed within four hours. In conclusion, it can be concluded that the immobilized Aspergillus oryzae β-Galactosidase obtained in this thesis can be used in the industrial production of lactose-free milk.Öğe Alternative Tempering of Sugar-Free Dark Chocolates By βv Seeding: Sensorial, Micro-structural, and Some Physical Properties and Volatile Profile(International Journal of Food Engineering, 2019) Toker, O.S.; Oba, S.; Palabiyik, I.; Rasouli Pirouzian, H.; Artik, N.; Sagdic, O.In this study, sugar-free dark chocolate was produced from isomalt and maltitol by βV seeding technique as an alternative to conventional tempering process. The effect of βV seed concentrations on the particle size dis- tribution, textural, rheological and melting properties of the end products was studied, and the results were compared with those of conventional sugar-free dark chocolates. For this aim, conched dark chocolates were melted and crystallized with βV seeds added at different concentrations (0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 %, m/m). Conventional tempering process was performed by using temper machine (47–27–32 °C). Brightness, chroma, whiteness index and tetramethyl pyrazine content (as marker compounds of dark chocolate volatile compound) were not influenced by seeding technique compared to conventional tempering method. The water activity of the dark chocolate samples was substantially affected by βV seed level according to used bulk sweetener. How- ever, all the values were determined below 0.4 which is critical limit for chocolate. Regarding overall acceptabil- ity, sugar-free dark chocolates tempered by βv seeds had very close scores compared with conventional one, implying that sugar-free chocolates can be produced by βv crystals with desired quality characteristics similar to conventional samples. Results of this study showed that it is possible to produce sucrose-free dark chocolates by using βV seeds with desired quality similar to chocolate produced by using conventional tempering.Öğe Chocolate Quality and Conching(Trends in Food Science and Technology, 2019) Toker, O.S.; Palabiyik, I.Background: Conching is the processing step in which chocolate is subjected to long-term heat treatment, me- chanical forces and addition of fat and emulsifiers. There is an important relationship between the chocolate flavour and the type of conching process. However, it is a costly processing step due to long duration of high temperature application. Scope and approach: In order to increase the level of chocolate quality and microbiological safety, the raw materials used as well as the process methods and parameters are of importance. In particular, the knowledge of how conching process affects the main quality parameters of chocolate can lead to better quality product in a more cost-effective way. Therefore, the objective of this study is to provide a general overview on the relation between the type of conching processes and chocolate main quality parameters (safety, aroma, color, texture and flow behavior), and also on the innovative conching applications. Key findings and conclusions. With the conching process, significant changes occur in physical, physico- chemical and sensory properties of chocolate. Therefore, in addition to tempering and refining steps, conching process should also be considered to produce high quality products at a more cost-effective way. As a result of innovative modifications to be made in the conching process, it is possible to obtain a safe product with higher consumer acceptability. However, these targets should be reached with shorter conching application time to increase production efficiency.Öğe Effects of polyols on the quality characteristics of sucrose-free milk chocolate produced in a ball mill(RSC Advances, 2019) Homayouni Rad, A.; Rasouli Pirouzian, H.; Toker, O.S.; Genc Polat, D.Sucrose-free milk chocolates containing different types of bulk (isomalt, xylitol and maltitol) and high intensity (Stevia) sweeteners were produced by using a ball mill. The main quality characteristics of the formulated chocolates were evaluated and compared with those of the conventional sample containing sucrose. The Casson model was the best fitting model for the rheological data. Casson viscosity and Casson yield stress were significantly affected by the type of bulking agent in chocolates formulated with xylitol (p < 0.05). However xylitol notably improved the overall acceptability according to the sensory analysis results. Chocolates containing the sucrose replacers demonstrated lower Tonset values and higher enthalpy than the control sample. Sucrose-free chocolates illustrated a higher degree of particle agglomeration. Bulk sweeteners meanwhile seem to have high potential for milk chocolate production with low calorie values by using the ball mill technique. Industrial applications: the production of sucrose-free chocolates with conventional methods requires a lot of time and energy. Recently, using alternative methods for chocolate production has been raising interest in many small industries. This study proposed a ball mill method for the preparation of sucrose-free milk chocolates with physiochemical properties almost ranging in the standard limit defined for chocolate. Although using the ball mill method presents a more cost-effective technique for chocolate production and provides shorter processing times for small chocolate industries, it seems to be less efficient in evaporating moisture than the conventional processing. Challenges are still ahead for upgrading this alternative technique to be efficient in evaporating more moisture during operation ending in a high quality product.Öğe Using Spray Dried Sugar Bett Molasses in Ice Cream as a Novel Bulking Agent(International Journal of Food Science and Technology, 2019) Acan, Betül Gizem; Toker, O.S.; Aktar, T.; Tamturk, F.; Palabiyik, I.In this study, it is aimed to investigate and evaluate the use of molasses which is a by-product of sugar production as a novel bulking agent in ice cream as a sugar replacer. Sugar beet molasses (75%) and 12 DE maltodextrin (25%) were converted into powder form by spray drying. Spray-dried sugar beet molasses (SDSM) was then used as a substitute of sugar in different ratios (0:100, 25:75, 50:50, 75:25 and 100:0) in the ice cream products. The increased amount of SDSM decreased the overrun, L*, whiteness index (WI) and melting behaviours and increased a*, b*, total phenolic content, consistency and viscosity. Meanwhile, thermal properties have not been affected by the use of SDSM (P < 0.05). The sensory find- ings have been particularly interesting especially when replacing above 50% sugar with SDSM, aroma, flavour and general acceptability decrease. According to the results of this study, substituting 25% of total sugar with SDSM as a bulking agent can decrease cost of the product and improve total phenolic content and some quality parameters without compromising sensorial propertiesÖğe Developing Functional White Chocolate Incorparating Different Forms of EPA and DHA- Effects on Product Quality.(Elsevier Ltd, Temmuz 2018) Toker,Omer Said; Konar,Nevzat; Pirozian, H Rasouli; Oba, Şirin; Genç Polat, Derya; Palabıyık, İbrahim; Poyrazoğlu, Ender Sinan; Sağdıç, OsmanIn the present study, white chocolate was enriched with different forms (encapsulated form, microalgae containing form) of Eicosa-Pentaenoic-Acid (EPA) and Docosa-Hexaenoic-Acid (DHA). EPA/DHA sources were added after conching process. Main EPA/DHA percentage of the sources changed between 5.80-38.7 and 8.50–70.5 g/100 g, respectively in total fatty acid content. EPA and DHA contents of the chocolate samples increased to 226.8 and 54.3 mg/25 g chocolate, respectively, in a consequence of enrichment. Water activity (0.290–0.340), hardness (5.31–7.97 N), yield stress (2.09–3.87 Pa), plastic viscosity (1.06–1.62 Pa s), Tend (31.4–33.6 °C), energy required for complete melting (ΔH) (9.53–11.3 J/g) properties of the samples were affected significantly (P < 0.05), however these effects were tolerable and in narrow ranges. The use of EPA/DHA in different forms and origins affected the colour saturation, after taste and overall acceptance of the samples (P < 0.05). The findings of this study showed that it is possible to produce white chocolate fortified with EPA/DHA from microalgae origin and in free flowing powder form with desired quality. According to the results, it can be concluded that white chocolate can be used as a carrier of bioactive substances which are heat sensitive.Öğe Formulation of Dark Chocolate asCarier to Deliver Eicosapentaenoic and Docosahexaenoic Acids: Effects on Product Quality.(Elsevier Ltd, 15 Temmuz 2018) Toker,Omer Said; Konar,Nevzat; Palabıyık, İbrahim; Pirozian, H Rasouli; Oba, Şirin; Genç Polat, Derya; Poyrazoğlu, Ender Sinan; Sağdıç, OsmanIn this study, dark chocolate enriched with EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) was developed using various forms and origins. Quality characteristics such as physical, thermo-gravimetric, rheological, textural and sensory properties of chocolates were investigated. The highest EPA/DHA stability was determined in samples prepared by free-flowing powder and microencapsulated forms of omega-3 fatty acids (FA). The L∗ and C∗ values varied from 32.16–33.37 and 7.45–8.09, respectively for the all samples. Hardness values ranged between 6422 and 8367 N and the use of EPA/DHA in the triglyceride form caused softer chocolate whereas control sample was the hardest sample. Melting and rheological properties were not significantly affected by the studied EPA/DHA sources (P < 0.05). Microencapsulated EPA/DHA added chocolate was the most preferred source whereas sample with algae oil showed the lowest acceptability. According to the results, dark chocolate can be used for delivering omega-3 FA by considering their origin and physical form.Öğe Immobilization of Pectinex Ultra SP-L to Produce Fructooligosaccharides(Enzyme and Microbial Technology, 2005) Tanrıseven A., Aslan Y.Pectinex Ultra SP-L, a commercial enzyme preparation containing fructosyltransferase activity, was immobilized covalently onto Eupergit C and was used for the production of fructooligosaccharides. Immobilization resulted in 96% relative activity. The immobilized enzyme showed no decrease in activity for 20 batch reactions. Optimum conditions were not affected by immobilization, and the optimum pH and temperature for free and immobilized enzyme were 5.5–6.5 and 65 ?C, respectively. Immobilized enzyme was more stable at high pH and temperatures. The amount of fructooligosaccharides produced from 60% (w/v) sucrose solution using the free and immobilized enzyme was determined to be approximately 57% of the total sugar in the reaction mixtures. The kinetic parameters for free and immobilized enzyme were also determined. The immobilized Pectinex Ultra SP-L could be used for the production of fructooligosaccharides since the immobilization efficiency is quite high (96%) and immobilized enzyme retains its activity for 20 days without any decrease.Öğe Immobilization of Pectinex Ultra SP-L to produce galactooligosaccharides(Journal of Molecular Catalysis B: Enzymatic, 2007) Aslan Y., Tanrıseven A.Pectinex Ultra SP-L, a commercial enzyme preparation obtained from Aspergillus aculeatus, containing -galactosidase activity,was immobilized onto Eupergit C and was used for the production of galactooligosaccharides (GOS). Immobilization resulted in 100% binding yield and higher GOS yield (24%, w/v) with respect to soluble enzyme. Optimum conditions were not affected by immobilization, and optimum pH and temperature for free and immobilized enzyme were 4.0–5.0 and 55–60 ?C, respectively. Immobilized enzyme was more stable at high pH and temperatures. The amount of GOS produced from 30% (w/v) lactose solution using the free and immobilized enzyme was determined to be 12.8 and 15.8% (w/v) of the total sugar in the reaction mixture, respectively. The kinetic parameters for the free and immobilized enzyme were also determined. The immobilized Pectinex Ultra SP-L could be used for the production of galactooligosaccharides, since the immobilization yield is high (124%) and immobilized enzyme retains its activity for 20 days without any decrease.Öğe Immobilization of Penicillium lilacinum dextranase to produce isomaltooligosaccharides from dextran(Biochemical Engineering Journal, 2007) Aslan Y., Tanrıseven A.Penicillium lilacinum dextranase was immobilized covalently onto Eupergit C and was used for the production of isomaltooligosaccharides. Immobilization resulted in 90% relative activity. The immobilized enzyme showed no decrease in activity for 20 batch reactions. Optimum conditions were not affected by immobilization, and optimum pH and temperature for free and immobilized enzyme were 4.5–5.5 and 30–35 ?C, respectively. Immobilized enzyme was more stable at low and high pH and high temperatures. The kinetic parameters for the free and immobilized enzyme were also determined. The immobilized enzyme could be used for the production of isomaltooligosaccharides, since the immobilization efficiency is high (90%) and immobilized enzyme retains its activity for 20 days without any decrease.Öğe Improved Performance of Pseudomonas fluorescens Lipase by Covalent Immobilization onto Amberzyme(Turkish Journal of Biochemistry, 2013) Aslan Y. Handayani N, Stavila E, Loos KObjective: In this study, the conditions of covalent immobilization of Pseudomonas fluorescens lipase onto an oxirane-activated support (Amberzyme) were optimized to obtain a high activity yield. Furthermore, the operational and storage stabilities of immobilized lipase were tested. Methods: Optimum conditions for immobilization were determined by changing individually the conditions (pH from 5 to 9; buffer concentration from 0.025 to 2.5 M; amount of Amberzyme from 100 to 500 mg and duration of immobilization from 24 to 120 h). Amounts of protein and the activity of enzyme were determined by UV/Vis (PYE UNICAM SP8-200 UV/Vis spectrophotometer). Results: Immobilization conditions (pH and molar concentration of immobilization buffer, enzyme/support ratio and immobilization duration) significantly affected the immobilization efficiency. 100% immobilization yield and 145% activity yield were achieved by optimizing the immobilization conditions. Operational and storage stabilities of immobilized lipase were determined as well. The immobilized enzymes retained its activity for 20 consecutive batch reactions. Furthermore, the immobilized lipase showed a high storage stability as no decrease in its activity was observed for 20 days. Conclusion: Our results obtained in the present study are the best in the covalent immobilization of Pseudomonas fluorescens lipase in the literature. Therefore our future studies will focus on using the immobilized Pseudomonas fluorescens lipase for the production of biodiesel, hydrolysis of oils and various important esterification reactions.Öğe The Effect of Dielectric Barrier Discharge Plasma Treatment on The Microorganisms Found in Raw Cow's Milk(Turkish Journal of Agricultural Research, 2016) Aslan Y.Milk is an essential source of nutrition especially for the breastfed infants. Sterilization of milk is necessary because it can be contaminated by microorganisms due to unhygienic collection and storage conditions. In this study, the sterilization of raw cow milk was performed by using dielectric barrier discharge (DBD) plasma method. Raw milk was transferred to the plasma reactor and dielectric barrier discharge cold plasma was performed by changing various parameters including voltage, exposure time and frequency. It was found that dielectric barrier discharge cold plasma is very effective at sterilization of raw cow milk particularly at room temperature. The optimum parameters that wee demonstrated to completely kill the bacteria in raw milk were experimentally determined to be a 3 kV application voltage, 3 min exposure time and 500 Hz frequency. Additionally, there was almost no important change in pH value of cow milk after DBD plasma treatment (The average pH was 6.2). Pathogen microorganisms found in milk produces metabolites (during storage and transport) that have adverse effects on health. The method developed by us in this study will be used in a future study to develop a prototype of a sterilization device that can be integrated into the current milking system and can be continuously applied. Thus, the sterilization of milk during milking process could potentially be an extremely effective method for maintaining its quality and nutritional value. Furthermore, since the DBD plasma method is an ultra fast process that operates under ambient temperatures (ideal for thermolabile products) at a low running cost and is environment-friendly, it can be used for the sterilization of a wide range of liquid food products.
