90 research outputs found
Ultrasonic pretreatment of carrot slices: Effects of sonication source on drying kinetics and product quality
No full textCakmak, Hulya/0000-0002-4936-939X; Tavman, Sebnem/0000-0002-3069-1709; YILMAZ, Burcin/0000-0003-0719-4090In this study effects of ultrasonic pretreatment with different sonication sources on drying behavior of carrot slices were evaluated. Fresh carrot slices were pretreated with ultrasonic probe at 65, 75 and 85 W or ultrasonic bath at 10, 20 and 30 degrees C for 3, 5 and 10 min before air drying. Water gain % and solid loss % of pretreated samples were calculated and color values. beta-carotene content and rehydration ratios of dried samples were determined. Drying behavior of the pretreated samples was evaluated and the drying data were fitted to thin layer drying models. Constant drying rate period was not observed for the carrot slices; however two definite falling-rate periods having different slopes were obtained. Drying time was significantly reduced (up to 20%) depending on the type of pretreatment. the redness value, total color difference and Chroma values of pretreated and control samples were in the same group (p>0.05). beta-carotene content of ultrasonic bath pretreated samples were significantly higher than the samples pretreated with ultrasonic probe and the sample dried without any pretreatment as well (p<0.05). Also rehydration ratios of control samples were found lower than the ultrasound pretreated samples.Ege University Scientific Research Projects CommissionEge University [13-MUH-019]This study was financially supported by Ege University Scientific Research Projects Commission with the project no: 13-MUH-019
Thermal conductivity of granular food materials
No full textASME PDProceedings of the 1996 3rd Biennial Joint Conference on Engineering Systems Design and Analysis, ESDA. Part 7 (of 9) -- 1 July 1996 through 4 July 1996 -- Montpellier, Fr -- 46123In this study, the bulk thermal conductivity of Gediz 75, Ege 88 and Spanish varieties of Triticum durum wheat has been determined at ambient temperature by a modified hot wire method. The bulk thermal conductivities ranged from 0.129 to 0.3717 W/m.K for the moisture contents of the wheat samples ranging from 6.9 to 55 percent wet basis. The thermal conductivity of each variety of wheat increased linearly with moisture content. Various conduction models for granular porous systems are also considered and the experimental results are compared with the values calculated from the models. It has been found that the parallel model predicts best the value of the bulk thermal conductivity
Thermal diffusivity determination of pizza and puff pastry doughs at freezing temperatures
No full textThe thermal diffusivity of pizza and puff pastry doughs was measured in the temperature range from -35 to +15C by using time-temperature history method. Experimental data of thermal diffusivity were mathematically interpreted as a function of temperature by regression analysis in the frozen and unfrozen states. The thermal diffusivity of the frozen pizza and puff pastry doughs was greater than the unfrozen samples and decreased with temperature in the frozen state. Experimental values were compared to the prediction model and with previously documented values. A close agreement was found between the thermal diffusivity values determined experimentally and the values available in published literature
MEASUREMENT OF THERMAL CONDUCTIVITY OF EDIBLE OILS USING TRANSIENT HOT WIRE METHOD
No full textThermal conductivities of three different edible oils, namely sunflower oil, corn oil and olive oil, were measured at temperatures 25, 40, 60, and 80 degrees C. The measurements were carried out using a hot wire probe method. The calibration of the probe was performed using 0.3% agar gel with water and glycerin. In general, thermal conductivities of oils used in this study are found to be decreasing with temperature. The values of thermal conductivity measured are quite near to each other, the highest and the lowest being respectively 0.168 W/m K for sunflower oil at 25 degrees C and 0.152 W/m K for corn oil at 80 degrees C
Ohmic heating behaviour and rheological properties of ice cream mixes
No full textOhmic heating is an alternative heating method for Maras-type ice cream mix, which is a traditional ice cream in Turkey. Fast and uniform heating is necessary for the pre-heating of ice cream mixes. Maras-type ice cream, produced in continuous system, was investigated in this study. The results obtained were compared with those of standard ice cream. The ice cream mix used for this study was supplied before the pasteurization step. A voltage gradient of 10-60 V/cm was used to heat the ice cream mixes ohmically from 4 degrees C to 80 degrees C. Temperature dependent electrical conductivity relations were obtained for different ohmic heating rates. Electrical conductivity of the standard type ice cream mix was lower than that of the Maras type ice cream mix. Fat content and temperature had an effect on the electrical conductivity values. The rheological properties of the ice cream mixes were also measured at 4, 25, 40, 60, 70, and 80 degrees C by a Brookfield viscometer. Experimental data were evaluated according to power the law model-rheological constants (K, n) of Maras type ice cream mix were found to be greater than the standard type ice cream mix and increased with temperature
Thermal diffusivity measurement of meat products
No full textThermal diffusivity is an important thermal property in modeling, simulation and control of various food processing operations. Thermal diffusivities of meat products were measured in the temperature range of -35 to +10 degrees C, by using time-temperature history method. At temperatures below the initial freezing temperature, thermal diffusivity increased markedly as the temperature decreased and increased with increasing moisture content. Experimental data on thermal diffusivity were mathematically interpreted as a function of temperature and composition by application of regression analysis. Good agreement was found between thermal diffusivity values determined experimentally and literature values
Modeling and Optimization of Ultrasound Assisted Extraction Parameters using Response Surface Methodology for Water Soluble Polysaccharide Extraction from Hazelnut Skin
No full textThe aim of this study is to evaluate optimum process conditions for water soluble polysaccharides (WSP) of plant waste materials such as hazelnut skin by using response surface methodologies (RSM). Polysaccharides from hazelnut skin were extracted by means of probe type sonication system using distilled water as a solvent with several sonication time, temperature and amplitude. Response surface models were applied by both Box–Behnken Design (BBD) and Central-Composite Design (CCD) for determining optimal condition which satisfies both maximizing polysaccharide yield and minimizing applied energy for sonication. Results showed that both BBD and CCD models represented the system with high regression coefficient (R2 > 0.95) and optimum conditions are 16.15 min, 45C, 50.29% amplitude with 0.733 desirability, 15.97 min, 45C, 47.27% amplitude with 0.712 desirability, respectively, for designs. Results of given conditions are 1.74% yield and 78.75 kJ consumption for BBD and 1.64% yield and 71.68 kJ for CCD. These results were validated by comparing experimental results at 15 min, 45C, 50% amplitude. As a consequence, it was observed that selected statistical models represent the system with a high accuracy and associating scores of each optimal condition is close enough to experimental results. Practical Applications: Hazelnut skin is accepted as a waste material and there is no known application area in food industry. Although this waste can be utilized as bioactive polysaccharide source, extraction procedure requires enzymatic and chemical treatments. Sonication can be applied to extract water soluble polysaccharide from hazelnut skin and this method can be applied practically for further studies. Because during polysaccharide extraction, sonication improves uniform heat distribution and enhances mass transfer while decreasing activation energy due to the increase in particle velocity, intense mixing, cell disruption and partial hydrolysis. These effects make sonication profitable tool to obtain bioactive polysaccharides from plant waste materials. RSM is an easy way to organize experiments and optimize complex system such as extraction. On the other hand BBD design is easier and more applicable then CCD especially when the process has some concerns such as difficulties to adjust required level of parameters for CCD. © 2016 Wiley Periodicals, Inc
Ultrasound assisted extraction of polysaccharides from hazelnut skin
No full textIn this study ultrasound assisted extraction (UAE) of polysaccharides from hazelnut skin has been studied. Optimum sonication time has been evaluated depending on responses such as amount of carbohydrate and dried sample and thermogravimetric analysis. Chemical and structural properties of extracted material have been determined by Fourier transform spectroscopy attenuated-total reflectance (FTIR-ATR) spectroscopy. Pretreated hazelnut skin powders were extracted in distilled water. Mixture was sonicated by ultrasonic processor probe for 15, 30, 45, 60, 90, and 120min. The results of UAE showed that maximum ethanol insoluble extracts in 60min and the highest dry matter content could be obtained in 120min extraction. Although total carbohydrate content of ethanol insoluble dry extract decreased with time, total carbohydrate in ethanol soluble fraction increased. Polysaccharides extracted from hazelnut skin were assumed to be pectic polysaccharide according to the literature survey of FTIR analysis result. Application time of UAE has an important effect on extraction of polysaccharide from hazelnut skin. This affect could be summarized by enhancing extraction yield up to critical level. Decrease of the yield in ethanol insoluble part could be explained by polymer decomposition. Most suitable model was hyperbolic model by having the lowest root mean square error and the highest R-2 values.Celal Bayar University Scientific Research Project DepartmentCelal Bayar University [2014/04]Financial requirement of this study was supported by Celal Bayar University Scientific Research Project Department (No: 2014/04)
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