REFRACTANCE WINDOWTM TECHNOLOGY
The uncontrolled humidity and the temperature of ambient air within the dryer leads to a wide variation in dryer performance and product quality. For example, a dryer operating in a dry climate performs differently in a humid climate. Similarly, dryer performance varies in cold and hot climates, and from season-to-season or day to night at the same location. Pumpkin Microwave , freeze-drying, and convective greenhouse Drying kinetics, kinetics and rehydration indexes, quality. Microwave drying methods are suitable for pumpkin dehydration Monteiro et al.
Fractal dimension and lacunarity were used to study the structure and irregularities of dried jackfruit. SEM images were analyzed via the FracLac plug-in used in ImageJ software. The effect of high power airborne ultrasound and microwaves Revolutionizing Food Drying: The Advantages of Refractance Window Dryer on convective drying effectiveness and quality of green pepper. Torringa E., Esveld E., Scheewe I., Berg R.V.D., Bartels P. Osmotic dehydration as a pre-treatment before combined microwave-hot-air drying of mushrooms.
In other hand, the best quality (lowest ΔE, lowest BI, and highest WI) is observed for the sample blanched in 5% citric acid at 60 °C. Finally, the effect of the different pretreatment methods on the quality of the surface structure of the dried samples was studied by scanning the surface structure using Scanning Electron Microscope . RWD was found to take much less time to dry the dragon fruit, around 960 min, compared to the other drying methods, which took 1200 to 1320 min.
The authors claimed that refractance window drying has high potential to be used in bone broth powder production. In a recent study, Tontul et al comparatively researched refractance window drying and freeze drying in kefir powder production. According to study, refractance window drying provided better flowability and cohesiveness in kefir powder. Moreover, better wettability, hygroscopicity and solubility was observed in refractance window dried powders compared to those of freeze drying.
Calín-Sánchez Á., Kharaghani A., Lech K., Figiel A., Carbonell-Barrachina Á., Tsotsas E. Drying kinetics and microstructural and sensory properties of black chokeberry as affected by drying method. Cano-Lamadrid M., Lech K., Michalska-Ciechanowska A., Wasilewska M., Figiel A., Wojdyło A., Carbonell-Barrachina Á. Influence of osmotic dehydration pre-treatment and combined drying method on physico-chemical and sensory properties of pomegranate arils, cultivar mollar de elche. Vadivambal R., Jayas D.S. Non-uniform temperature distribution during microwave heating of food materials—A review.
Hot water comes from the thermostatic bath and circulates to the container. All samples were placed on the Mylar film as a thin layer of 3 mm. Samples were taken each 10 minutes for microbiological analysis and moisture content determination until the drying process was completed.
It uses circulating hot water at atmospheric pressure as a heating medium for the material to be dehydrated . These drying technologies differ in drying speed, energy efficiency, product quality, dryer costs, and technological simplicity. The main technical challenge is to identify a relatively inexpensive drying technology that gives high-quality products, even from heat-sensitive materials, as most drying technologies entail application of high temperatures. This causes loss of flavor, nutrients, and bioactive compounds. The color, microstructure, shrinkage, and bulk density of dried fruit products are all affected by drying methods and processing conditions . Refractance Window™ 1,2,3 as a relatively new film drying technique is characterized by short time exposure of foods to relatively low temperatures (Magoon, 1986, Nindo et al., 2003).
The use of the modified Midilli and Gompertz model allowed observing that there is a correlation between the drying rate and the cellular inactivation rate . When the drying temperature increases, kd and k increase, which indicates that the faster the moisture in the product is lost, the faster the cell death rate increases in the product. The above is consistent with the phenomena aforementioned, where it is stated that cell death can be caused by the migration of water from the microorganism to the environment.
This review paper aims to comprehend the RW drying system more mechanistically to understand better the principles, diffusion models explaining the transfer processes, and emerging novel hybrid drying approaches. The postharvest losses of agricultural and horticultural crops are high as a result of the lack of postharvest handling, storage, and processing technologies in India. Over the years, drying has been an essential food preservation strategy for reducing postharvest losses and extending the shelf life of products. Traditional drying techniques exhibit a negative impact on the flavour, colour, nutritional properties, and retention of bioactive components due to the high-temperature exposure. An alternative for traditional drying methods is required to retain quality and maintain greater nutritional content in processed foods.
It is suggested that radiation heat transfer is one of the dominant modes of heat transfer that promotes faster drying. However, no mathematical model-based mechanistic understanding of this process is available to support the above hypotheses, which is the objective of the present work. Computed results indicate that there is only a 5% increase in transmission of IR radiation through Mylar between a dry and wet product.
An experimental study was conducted to see the effect of different pretreatment methods on the kinetics and quality of microwave-dried apple samples. For drying kinetics, no significant effect is observed for the blanched and electric field treated samples. However, a reduction in drying time by a value of 14.6–20.3% is observed for frozen samples.
Fractal dimension and lacunarity were used to study the structure and irregularities of dried jackfruit. SEM images were analyzed via the FracLac plug-in used in ImageJ software. The effect of high power airborne ultrasound and microwaves Revolutionizing Food Drying: The Advantages of Refractance Window Dryer on convective drying effectiveness and quality of green pepper. Torringa E., Esveld E., Scheewe I., Berg R.V.D., Bartels P. Osmotic dehydration as a pre-treatment before combined microwave-hot-air drying of mushrooms.
In other hand, the best quality (lowest ΔE, lowest BI, and highest WI) is observed for the sample blanched in 5% citric acid at 60 °C. Finally, the effect of the different pretreatment methods on the quality of the surface structure of the dried samples was studied by scanning the surface structure using Scanning Electron Microscope . RWD was found to take much less time to dry the dragon fruit, around 960 min, compared to the other drying methods, which took 1200 to 1320 min.
The authors claimed that refractance window drying has high potential to be used in bone broth powder production. In a recent study, Tontul et al comparatively researched refractance window drying and freeze drying in kefir powder production. According to study, refractance window drying provided better flowability and cohesiveness in kefir powder. Moreover, better wettability, hygroscopicity and solubility was observed in refractance window dried powders compared to those of freeze drying.
Calín-Sánchez Á., Kharaghani A., Lech K., Figiel A., Carbonell-Barrachina Á., Tsotsas E. Drying kinetics and microstructural and sensory properties of black chokeberry as affected by drying method. Cano-Lamadrid M., Lech K., Michalska-Ciechanowska A., Wasilewska M., Figiel A., Wojdyło A., Carbonell-Barrachina Á. Influence of osmotic dehydration pre-treatment and combined drying method on physico-chemical and sensory properties of pomegranate arils, cultivar mollar de elche. Vadivambal R., Jayas D.S. Non-uniform temperature distribution during microwave heating of food materials—A review.
Hot water comes from the thermostatic bath and circulates to the container. All samples were placed on the Mylar film as a thin layer of 3 mm. Samples were taken each 10 minutes for microbiological analysis and moisture content determination until the drying process was completed.
It uses circulating hot water at atmospheric pressure as a heating medium for the material to be dehydrated . These drying technologies differ in drying speed, energy efficiency, product quality, dryer costs, and technological simplicity. The main technical challenge is to identify a relatively inexpensive drying technology that gives high-quality products, even from heat-sensitive materials, as most drying technologies entail application of high temperatures. This causes loss of flavor, nutrients, and bioactive compounds. The color, microstructure, shrinkage, and bulk density of dried fruit products are all affected by drying methods and processing conditions . Refractance Window™ 1,2,3 as a relatively new film drying technique is characterized by short time exposure of foods to relatively low temperatures (Magoon, 1986, Nindo et al., 2003).
The use of the modified Midilli and Gompertz model allowed observing that there is a correlation between the drying rate and the cellular inactivation rate . When the drying temperature increases, kd and k increase, which indicates that the faster the moisture in the product is lost, the faster the cell death rate increases in the product. The above is consistent with the phenomena aforementioned, where it is stated that cell death can be caused by the migration of water from the microorganism to the environment.
This review paper aims to comprehend the RW drying system more mechanistically to understand better the principles, diffusion models explaining the transfer processes, and emerging novel hybrid drying approaches. The postharvest losses of agricultural and horticultural crops are high as a result of the lack of postharvest handling, storage, and processing technologies in India. Over the years, drying has been an essential food preservation strategy for reducing postharvest losses and extending the shelf life of products. Traditional drying techniques exhibit a negative impact on the flavour, colour, nutritional properties, and retention of bioactive components due to the high-temperature exposure. An alternative for traditional drying methods is required to retain quality and maintain greater nutritional content in processed foods.
It is suggested that radiation heat transfer is one of the dominant modes of heat transfer that promotes faster drying. However, no mathematical model-based mechanistic understanding of this process is available to support the above hypotheses, which is the objective of the present work. Computed results indicate that there is only a 5% increase in transmission of IR radiation through Mylar between a dry and wet product.
An experimental study was conducted to see the effect of different pretreatment methods on the kinetics and quality of microwave-dried apple samples. For drying kinetics, no significant effect is observed for the blanched and electric field treated samples. However, a reduction in drying time by a value of 14.6–20.3% is observed for frozen samples.
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