The effect of ohmic heating pretreatment on drying of apple

[EN] In this study, effects of ohmic pretreatment on the drying rates and color kinetics of apple were investigated. Apple slices were treated at different electric field strengths (20-30 and 40 V/cm) at 60°C for 1 min. Drying process was applied at 60˚C-2 m/s by using a tray-dryer. ΔE and moisture content were calculated. These values were fitted to the semi-theoretical thin-layer drying and the zero and first-order kinetic model. The shortest drying time was found samples treated with 30 V/cm. Wang&Singh model gave the superior fit to the experimental data. ΔE fitted well to the zero-order kinetic model.Kutlu, N.; Yilmaz, MS.; Arslan, H.; Isci, A.; Sakiyan, O. (2018). The effect of ohmic heating pretreatment on drying of apple. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1487-1494. https://doi.org/10.4995/IDS2018.2018.7375OCS1487149

Optimization of Ethanol Production From Microfluidized Wheat Straw by Response Surface Methodology

In this study, wheat straw was pretreated with a microfluidizer to improve its enzymatic hydrolysis and ethanol yields. The pretreatment was performed at various pressures (500, 1000, and 1500bar) and solid loadings (1, 2, and 3%). The microfluidized biomass was then subjected to hydrolysis and simultaneous saccharification and co-fermentation (SSCF) experiments at different enzyme loadings (5, 10, and 15 FPU/g dry wheat straw) using a mutant yeast. The results indicated that the microfluidization method alters the structure of biomass and leads to a reduction in lignin content. The samples pretreated at 1% solid loading contained the minimum lignin concentration and provided the maximum sugar and ethanol yields. These results signified that the microfluidization method is more effective on biomass at low solid loadings. The process conditions were optimized for higher ethanol and sugar yields using response surface methodology (RSM). The optimum pressure and solid and enzyme loadings were found as 1500bar, 1%, and 15 FPU/g dry wheat straw, respectively. The yields obtained at this condition were 82%, 94%, and 65% for glucose, xylose, and ethanol, respectively. High sugar yields implied that microfluidization is an effective pretreatment method for cellulosic ethanol production. On the other hand, low ethanol yield may indicate that the microorganism was sensitive to inhibitory compounds present in the fermentation medium

Estimation of Dielectric Properties of Cakes Based on Porosity, Moisture Content, and Formulations Using Statistical Methods and Artificial Neural Networks

Dielectric constant (DC) and dielectric loss factor (DLF) are the two principal parameters that determine the coupling and distribution of electromagnetic energy during radiofrequency and microwave processing. In this study, chemometric methods [classical least square (CLS), principle component regression (PCR), partial least square (PLS), and artificial neural networks (ANN)] were investigated for estimation of DC and DLF values of cakes by using porosity, moisture content and main formulation components, fat content, emulsifier type (Purawave (TM), Lecigran (TM)), and fat replacer type (maltodextrin, Simplesse). Chemometric methods were calibrated firstly using training data set, and then they were tested using test data set to determine estimation capability of the method. Although statistical methods (CLS, PCR and PLS) were not successful for estimation of DC and DLF values, ANN estimated the dielectric properties accurately (R (2), 0.940 for DC and 0.953 for DLF). The variation of DC and DLF of the cakes when the porosity value, moisture content, and formulation components were changed were also visualized using the data predicted by trained network

Investigation of dielectric properties of different cake formulations during microwave and infrared-microwave combination baking

Dielectric properties can be used to understand the behavior of food materials during microwave processing. Dielectric properties influence the level of interaction between food and high frequency electromagnetic energy. Dielectric properties are, therefore, important in the design of foods intended for microwave preparation. In this study, it was aimed to determine the variation of dielectric properties of different cake formulations during baking in microwave and infrared-microwave combination oven. In addition, the effects of formulation and temperature on dielectric properties of cake batter were examined. Dielectric constant and loss factor of cake samples were shown to be dependent on formulation, baking time, and temperature. The increase in baking time and temperature decreased dielectric constant and loss factor of all formulations. Fat content was shown to increase dielectric constant and loss factor of cakes

THE EFFECT OF DIFFERENT FORMULATIONS ON PHYSICAL PROPERTIES OF CAKES BAKED WITH MICROWAVE AND NEAR INFRARED-MICROWAVE COMBINATIONS

The aim of this study was to determine the effect of different formulations on color and textural characteristics of different cakes during baking in microwave and near infrared-microwave combination ovens. For comparison, cakes were also baked in conventional ovens. Color and hardness for both types of baking schemes were found to be dependent on formulation. Cakes containing Simplesse (TM), a fat replacer consisting mostly of whey protein, baked in microwave and near infrared-microwave combination ovens were found to be the firmest cakes

Comparison of antifungal activity of essential oils of clove, lemongrass and thyme for natural preservation of dried apricots

Currently, the majority of fresh apricots destined for the production of dried apricots undergo sulphur oxide fumigation before drying to protect the fruit against fungal spoilage. To eliminate the use of sulphite, packaging assisted with essential oil is a promising strategy to increase shelf-life of dried apricots since it does not impact its flavor characteristics. In this study, three essential oils were selected: clove, lemongrass and thyme. They were screened for antifungal activity against Eurotium spp. with different methods: micro- and macro-dilution and agar-diffusion. Growth/no-growth data were used to develop models for all three methods. Clove exerted the strongest antifungal activity with an inhibitory concentration of 0.075%, 0.035% and 0.05% through respectively micro-dilution, macro-dilution and agar diffusion. For thyme the following values were obtained: 0.775%, 0.070% and 0.100%. This means that the antifungal activity of thyme is 10 times lower in micro-dilution and 2 times lower in macro-dilution and agar diffusion compared to clove. Through micro-dilution, lemongrass was found to have the second highest antifungal activity (0.25%). When used in the volatile atmosphere of dried apricots and in macro-dilution, the antifungal activity of lemongrass was the lowest, with respective values of > 0.200% and 0.105% for G/NG prediction

Deep Eutectic Solvent-Based Extraction of Phenolic Compounds from Pomegranate (Punica granatum L.) Peel

In this study, the effect of deep eutectic solvent on the extraction of phenolic compounds (TPC) from pomegranate peel was investigated. The extraction was performed using an ultrasound bath. The results were compared with conventional extraction. In addition, different solvents (such as water and ethanol) were also examined to determine the efficacy of deep eutectic solvents. The highest TPC values by ultrasound assisted extraction method were found as 154.7, 171.2 and 195.1 mg GAE/g dry matter for water, deep eutectic solvent and ethanol-water (50:50 (v/v)), respectively. The difference in TPC values between ethanol-water and deep eutectic solvent was statistically insignificant. The shortest extraction time was obtained using deep eutectic solvent for ultrasound assisted extraction. The TPC values obtained during conventional extraction were lower compared to that of ultrasound extraction

Functional properties of microwave-treated wheat gluten

In this study, the effects of microwave treatments on solubility, foaming and emulsifying properties of gluten were investigated. The solubility of microwave-heated gluten proteins gradually decreased as the treatment time increased, at all power levels applied. The highest solubility values were obtained for gluten samples microwave treated at 50% power level. The lowest emulsifying capacity values were obtained with the samples heated at 100% power level at all treatment times. The emulsifying stability values of microwave-heated gluten samples were found to be slightly higher than those of the control sample. However, there were no significant differences among the microwave power levels at all treatment times in terms of the emulsifying stability values. The foam volumes of the samples treated at 80 and 100% energy levels were slightly higher than those of the control gluten. The foam stability values of microwave-heated gluten samples gradually increased with treatment time at all power levels, which were more pronounced at 100% power level. Generally, microwave treatment did not cause major changes on the protein electrophoretic patterns of gluten samples at the power levels used

Effect of Drying on Porous Characteristics of Orange Peel

The purpose of the study was to determine the effects of different temperatures (40, 50 and 60 degrees C) and air velocities (1 and 2 m/s) on shrinkage, porosity, pore size distribution, color and microstructure of orange peel. Empirical models were also proposed to predict shrinkage and porosity as a function of moisture. A strong negative correlation was determined between moisture and shrinkage. Air temperature had no significant impact on the final shrinkage and porosity values. During drying, porosity of the samples first increased until a critical value, at which point further decrease in moisture resulted in collapse of pores. The porosity of the orange peel was correlated with moisture by a third- order polynomial. Pore size distribution curve of raw sample showed two major peaks, a wider and a sharper peak at around 19.8 and 7.18 mu m, respectively. After drying, the peaks became shorter and the curve shifted to the left, indicating that the amount of pores and their diameter decreased. The SEM analysis revealed that at extreme process conditions, the orange peel surface was cracked and the characteristic distribution of the waxy components was obstructed

A Study on Degree of Starch Gelatinization in Cakes Baked in Three Different Ovens

The main objective of the study was to determine the effects of different baking ovens and different cake formulations on the degree of starch gelatinization during cake baking. Baking was performed in microwave, infrared-microwave combination, and conventional ovens. Starch gelatinization levels of fat free, 25% fat, and 25% Simplesse (TM)-containing cake samples were examined using differential scanning calorimeter (DSC) and rapid visco analyzer (RVA). Both DSC and RVA results showed that increasing baking time increased gelatinization level for all baking types significantly. It was also found that the effect of fat content on starch gelatinization was different depending on the type of baking. Addition of fat reduced the degree of starch gelatinization in conventional baking. However, fat enhanced the gelatinization in microwave and infrared-microwave combination ovens. Usage of Simplesse (TM) as a fat replacer decreased the starch gelatinization in all types of baking significantly. There was insufficient starch gelatinization in microwave-baked cakes in which the degree of gelatinization ranged from 55% to 78% depending on formulation. On the other hand, it ranged from 85% to 93% in conventionally baked cakes. Combining infrared with microwaves increased degree of starch gelatinization (70-90%)