Quantitative understanding of Refractance Window drying

His scientific efforts helped development and evolve the refractance window drying technique into InfraRWD. InfraRWD offers faster, more efficient and more economical drying than refractance window drying. The retention of food quality in a drying process rather than mere extension of shelf life has gained prominence because of consumers demand for more health-promoting foods. InfraRWD dryer can be used in three different mode, namely refractance window drying, infrared drying and infrared assisted refractance window drying.
Zhang, Y.; Zhao, J.H.; Ding, Y.; Xiao, H.W.; Sablani, S.S.; Nie, Y.; Tang, X.M. Changes in the vitamin C content of mango with water state and ice crystals under state/phase transitions during frozen storage. Caparino, O.A.; Nindo, C.I.; Tang, J.; Sablani, S.S.; Chew, B.P.; Mathison, B.D.; Powers, J.R. Physical and chemical stability of Refractance Window®–dried mango (Philippine ‘Carabao’ var.) powder during storage. Cichella Frabetti, A.C.; Refractance Window Dryer Durigon, A.; Laurindo, J.B. Effect of process variables on the drying of guava pulp by cast-tape drying. Dalla Nora, C.; Müller, C.D.R.; de Bona, G.S.; De Oliveira Rios, A.; Hertz, P.F.; Jablonkski, A.; de Jong, E.V.; Flôres, S.H. Effect of processing on the stability of bioactive compounds from red guava and guabiju . And C.I.O.-M.; methodology, Y.M.L.-R.; formal analysis, Y.M.L.-R.; investigation, Y.M.L.-R.; resources, Y.M.L.-R., A.A-A.

Powder flow behavior may be inferred from the ratio of bulk and tapped densities . In this study, the tapped density ranged from 0.596/cm3 to 0.774/cm3, depending on the drying technique. This study revealed that the refractance window dried jackfruit powder had the least tapped density.
Effect of different drying techniques on sensory characteristics of loquat cultivar ‘Algar’ . Numerical and experimental analysis of heat and moisture transfer during drying of Ataulfo mango. Castoldi, M.; Zotarelli, M.; Durigon, A.; Carciofi, B.; Laurindo, J. Production of tomato powder by refractance window drying. Jafari, S.; Azizi, D.; Mirzaei, H.; Dehnad, D. Comparing quality characteristics of oven-dried and refractance window-dried kiwifruits. Topuz, A.; Feng, H.; Kushand, M. The effect of drying method and storage on color characteristics of paprika. Sanjinez-Argandoña, E.; Cunha, R.; Menegalli, F.; Hubinger, M. Evaluation of total carotenoids and ascorbic acid in osmotic pretreated guavas during convective drying.
That confirms that the films were transparent to radiation to a high degree, which allowed the heating of the sample, as discussed in the previous section. The limited access to non-renewable resources for packaging materials has turned the focus to biopolymers. These films are used for food packaging, adhesives, biocomposites, and hydrogel films. It gently removes water from our foods while protecting the vitamins, minerals and micronutrients. Working with farm-fresh foods from our amazing Farm Fresh Partners is central to our identity, however preserving the vital compounds of those foods as they make their way into the bottle isn’t easy. Each step of our process was thoughtfully created to maximize the preservation of nutrition, however no step in the process quite illustrates this like our Refractance Window Dryer.

Miller25 method was used for the quantification of total reducing sugars in the samples. 3 mL of the sample and 3 mL of DNS reagent were added in the test tube and kept in the hot water bath at 60 °C for 15 min. 1 ml Rochelle salt solution was then added to the tubes and were allowed to cool down. The absorbance was taken at 575 nm using spectrophotometer (Bausch & Laumb Spectronic-20). The standard curve was used to calculate the concentration of reducing sugars (20–100 g mL−1). Where yk is the model's projected response value; β0, βi, βii, and βij are constants, regression coefficients for linear, quadratic, and interaction effects factors, and xi is the coded independent variable.
The TFC values were 2.82 and 2.84 mg QE/g for the slice and pulp samples, respectively. The TFC value was higher in the FD samples than in other drying methods, mainly due to the lower temperatures of FD, which contribute to the preservation of flavonoid compounds. After the control sample, the RWD sample had higher crude fiber content values, which were 0.96 and 0.98 for the slice and pulp samples, respectively. The FD sample had the lowest value because the fiber content may have been decreased due to the application of a lower temperature during processing.

Hu et al. reported similar results of microstructure of polysaccharides from Crassostrea gigas using electric heating air-blowing drier at 100 °C for 12 h. They elucidated that convective drying process result in irregular shape and rough surface of polysaccharides particles which indicate lesser antioxidative and bioactive activity because of greater surface area. Nindo et al. carried out experiments with pumpkin purée to evaluate the energy efficiency and the effect of the microbial reduction of RW. This technique was able to reduce the moisture content from 80% to 5% in less than 5min. The results showed that RW is energy efficient and has a good capacity for microbial reduction.
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.
Nowicka P., Wojdyło A., Lech K., Figiel A. Chemical composition, antioxidant capacity, and sensory quality of dried sour cherry fruits pre-dehydrated in fruit concentrates. Figiel A. Drying kinetics and quality of beetroots dehydrated by combination of convective and vacuum-microwave methods. Calín-Sánchez Á., Figiel A., Hernández F., Melgarejo P., Lech K., Carbonell-Barrachina Á. Chemical composition, antioxidant capacity, and sensory quality of pomegranate (Punica granatum L.) arils and rind as affected by drying method.

The use of hot water as the heat transfer medium and at temperatures just below boiling is a design  feature that is unique to this drying method. First mechanism which was proposed for RW drying suggested that in this type of dryer, thermal energy from circulating hot water is transported to the wet product via a plastic interface which is relatively transparent to infrared radiation. During RW drying, the three modes of heat transfer are active which include conduction , convection , and radiation (C. I. Nindo & Tang, 2007). Developed equipment that uses solar energy and operates under a vacuum.