Ohmic processing of liquid whole egg, white egg and yolk

The Ohmic heating rate of a food is highly influenced by its electrical conductivity. In this study, electricalconductivities, colour changes and system performance of liquid whole egg, white egg and yolk were determined on alaboratory scale static Ohmic heater by applying 30 V/cm voltage gradient. The samples were heated from room temperaturethrough to pasteurization temperature (19 – 60℃). In all cases, the linear temperature dependent electrical conductivityrelations were obtained. Conductivity measurements of liquid egg indicated that white egg is highly conductive compared toyolk and whole egg. The system performance coefficients for liquid egg samples were in the range of 0.814 to 0.857. Ohmicheating revealed better colour values from the values of heated samples for convectional heating.Keywords: egg, Ohmic heating, electrical conductivity, colou

Effect of Ultrasound on Mechanical Properties of Walnut

Walnut mechanical properties are an appropriate criterion for designing and adjusting the various parts of harvesting machines that are in contact with walnut. In this research, the aim is to find the effect of ultrasound factors on walnut mechanical properties to reduce walnut rupture force and energy. Walnuts were treated with three ultrasound time duration (5, 10, and 15 min) and three ultrasound bath temperatures (20, 35, and 50 ºC). After the walnuts were treated by ultrasound factors, wet and dried walnut samples were loaded at three loading speeds (0.5, 1.5, 2.5 mm/s) along width and length direction for determination of mechanical properties. Regarding the ANOVA results, the ultrasound time factor had the most effect on the rupture force, energy, and toughness. Results showed walnut ultrasound-treated samples had minimum rupture force and energy. Also, rupture force, required energy, and toughness decreased with increasing ultrasound bath temperature and the ultrasound time duration. The minimum walnut rupture force was obtained at 62.7 N in 25 min ultrasound time duration, 50 ºC bath temperature, 1.5 mm/s loading speed, and width loading direction for wet walnut sample

Analysis of the combinative effect of ultrasound and microwave power on Saccharomyces cerevisiae in orange juice processing

High temperature in conventional method for juice pasteurization causes adverse effects on nutrients and nutritional value of food. The objective of this study was to examine the effect of microwave output power, temperature, ultrasound power, and ultrasonic exposure time on Saccharomyces cerevisiae in orange juice. Based on our findings, microwave output power, ultrasound power, ultrasonic exposure time orange juice temperature were the most effective factors to reduce S. cerevisiae. The results showed that the quadratic model included was the best model for account. The model showed that regarding decrease of S. cerevisiae account microwave-induced temperature was more effective than microwave output power. Also, compared to microwave power, the ultrasound power was more effective on S. cerevisiae reduction. The optimum processing condition was 350 W microwave power, 35 °C temperature, 778.2 W ultrasonic power, and 11 min of exposure. Based on our result, the consumption energy was 142.77 J/mL with no remaining of S. cerevisiae. The results showed that the given scores by panelists to the combinative and conventional methods for color and flavor indices were significant (P b 0.05). Industrial Relevance: In order to reduce the adverse effects (loss of vitamins, flavor, and non-enzymatic browning) of the thermal pasteurization method, other methods capable of inactivation of microorganisms can be applied. In doing so, non-thermal methods are of interest, including pasteurization using high hydrostatic pressure processing (HPP), electric fields, and ultrasound waves. The ultrasound technology has been the main focus of studies in recent years. However, the main challenge facing the non-thermal technologies in food processing is the inactivation of pathogenic microorganisms and food spoilage agents, which can be achieved by various methods. The aim of present research was examined simultaneous effect of ultrasonic and microwave to remove microorganism. This research introduces new, innovative, and combined method for fruit juice pasteurization, and this method can benefit the food industry

Simulating and Evaluating the Effects of Air Passing through a Linear Parabolic Solar Collector on Some Properties of Leaving Air

In the current energy and environmental conditions, it is necessary to implement systems based on renewable energy sources in order to reduce energy consumption worldwide. Solar collectors have been studied for years, and many researchers have focused their attention on increasing their efficiency and cost-effectiveness. Solar collectors are implemented for heating domestic water, heating or industrial processes. A promising system that is not yet widely known is air heating by solar collectors, which can be an efficient way to use solar energy with lower investment costs, a system that can preheat the fresh air needed for heating, drying. In this research, the air was established between the absorbent space and its glass cover at speeds of 2, 4, and 6 m/s using a fan, and the effect of incoming air speed and weather conditions such as solar radiation intensity, wind speed, and ambient temperature on the outlet air temperature from the collector and the absorber rod temperature were checked. Based on the obtained results, the temperature of the air coming out of the collector and the temperature of the absorber decreases with the increase in the speed of the incoming air. The greatest impact of weather conditions on the temperature of the absorber rod is related to the intensity of the sun's radiation. The numerical analysis results were obtained with an error of 5% compared to the experimental results

Hydrothermal characteristics and quality of alfalfa cubes during transport

Alfalfa cubes are transported over long distances for export. The ambient conditions that the cubes may be exposed to in transit could vary from below freezing to in excess of 40°C and relative humidity up to 100%, especially when cubes are exported to humid regions of the Pacific Rim. Under humid condition, cubes absorb moisture and become prone to spoilage at high temperature. The objectives of this research were to determine time-temperature-humidity combinations for safe storage of cubes and to develop a model for estimating the hydrothermal dynamics of cubes during transport. Samples of commercial alfalfa cubes were exposed to combinations of temperatures from 9° to 39°C and relative humidities (RH) from 60% to 86% for 66 and 90 days in closed chambers. Cube moisture content, colour, density, hardness, durability, and time of appearance of molds were measured. Dynamic equations representing quality change with respect to time and storage conditions were developed. The cubes stored below 71% RH did not develop mold, but all of the cubes lost some degree of their greenness. Discoloration was severe at higher temperatures and humidities. Density, hardness, and durability of cubes declined significantly at 80% relative humidity. Data from instrumented containerized alfalfa cube shipments from Canada to Taiwan were analyzed. Temperatures and relative humidities were monitored during transit, and the moisture contents and durabilities of alfalfa cubes were measured on samples taken at the time of loading and unloading. The calculated spoilage potential agreed with the incidence of mold recorded at the time of unloading. Heat balance equations based on bulk thermal diffusivities and natural convection were developed. Several boundary conditions representing the dynamics of cube surroundings during shipments were investigated. It was shown that for prediction of the cube temperature, temperatures of both the head space above the cubes and the container ceiling were required. The moisture transfer within the cube pile in the container was modeled as a closed system, i.e., assuming no moisture transfer between inside and outside of the container. The calculated humidity ratio in the headspace was lower than the measured humidity ratio. It was concluded that the source of extra moisture inside the container was outside moisture penetrating into the container

Effects of fluidized bed drying on the quality of soybean kernels

AbstractThe effects of air temperature and velocity on the drying qualities (cracking, bulk density, shrinkage and rehydration) of soybean kernels in fluidized bed dryer were investigated. Drying was carried out at 80, 100, 120 and 140°C and air velocity of 1.8, 3.1 and 4.5m/s. Soybean kernels were dehydrated from the initial moisture content of 25% (w.b) to a final moisture content of 10%. The drying evaluation showed that high drying temperature and air velocity resulted in high cracking and low rehydration ratios (P<0.05). However, air velocity had no significant effect on bulk density and shrinkage of soybeans. By increasing the temperature and air velocity over their full ranges, drying time decreased from 380 to 50min. Cracking, bulk density, degree of shrinkage and rehydration ratio varied from 31.80% to 58.22%, 1101.31 to 1186.39kg/m3, 0.730 to 0.787, and 0.583 to 0.873, respectively. Regression equations were established which can be used for the estimation of the quality parameters as a function of the drying variables

Shrinkage and kinetic models for color changes of pretreated mushrooms with gamma irradiation during thin layer drying

Non-thermal processes such as irradiation are desierable methods to be used in combination with thermal ones in order to improve the quality of agricultural products. In this study, mushroom slices were initially irradiated under various doses (0 as control, 1.2, 2.4 and 3.6 kGy) and then dried at different temperatures (50, 60, 70 ºC). Then, the machine vision and image processing techniques were used to investigate any color changes and area shrinkage of dried mushroom slices. By increasing the irradiation dose, the change of the color indices (L* and b*), total color difference (ΔE), browning index and chroma decreased. While high temperatures had negative effect on these parameters except chroma. Moreover, the variation range of a* was insignificant during drying and the hue angle was between 70° to 78°. The zero and first order models for L*, b* and ΔE, as a function of drying time, showed high correlation coefficient for all treatments (0.91-0.99). Regarding shrinkage, by increasing irradiation dose and drying temperature, the area shrinkage slightly increased, where the temperature was more effective than irradiation dose

Texture Quality Analysis of Rainbow Trout Using Hyperspectral Imaging Method

In this study a hyperspectral imaging system (short wave infrared range from 1000 to 2500 nm) was used to model fish texture by experimental compression test. Partial least square–discriminate analysis modeling technique was used for classifying the samples by linking the hyperspectral information and their measured texture. The R2 of cross validation and prediction were 0.97 and 0.96, respectively. The root mean squared errors for cross validation and prediction were 0.07 and 0.09, respectively. Sensitivity and specificity for both class I and II were 1.00. Results indicated that hyperspectral imaging in short wave infrared range has ability to detect texture stiffness of rainbow trouts which is affected by freshness.peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=ljfp20status: publishe

Investigation of some pretreatments on energy and specific energy consumption drying of black mulberry

Massive consumption of energy in drying industry makes it a matter of challenge regarding economical aspects and limited recourses. Several methods for drying including hot air convection, vacuum, infrared and hot air convection-infrared technologies were applied in order to estimate the consumed energy during the drying of mulberry fruit. Moreover, microwave heating, chemical (ethyl oleate and potassium), mechanical (ultrasonic) and blanching (hot water) pretreatments were compared. According to the Results, maximum energy consumption was recorded when no pretreatment was performed. Microwave heating in the hot air convection-infrared dryer resulted in the lowest consumption of energy. Total energy requirement decreased with the temperature in the convection dryer res. Conversely, energy increased with air velocity. The vacuum dryer consumed the highest amount of energy which was measured to be 46.95 kWh while the lowest energy was recorded with using infrared-convective dryers. Also Experimental results showed that minimum and maximum specific energy consumption in the drying of black mulberry were associated with microwave pretreatment in IR-hot air dryer and control treatment in vacuum dryer, respectively. The minimum color change (ΔE) for drying of black mulberry was found in microwave pretreated samples dried with the vacuum dryer, yet maximum ΔE was observed in hot air dryer when no pretreatment was applied