Refractance Window Drying: An Emerging Technology for Heat-Sensitive Food Products

B. M. A. Amer, “Thin layer drying kinetics of mango puree in refractance window drying system,” Misr Journal of Agricultural Engineering, vol. B. Byaruhanga, “Optimization of drying conditions for jackfruit pulp using refractance window drying technology,” Food Science & Nutrition, vol. Refractance Window™ drying has primarily been studied to compare with other drying processes in terms of various quality attributes such as nutrition, flavor, color, aroma and antioxidant compounds.
The diffusion coefficient was higher when not considering shrinkage. These findings show that the RW™ technique is highly suitable for papaya drying; it makes it possible to dry the product reaching a Enhancing Food Processing: Refractance Window Dryer's Role in Nutrient Preservation low moisture content in shorter times, reducing the aw to values below 0.4 and preserving a similar color. This drying technology totally depends on Mylar film, which is the heart of this technology.

The RW drying showed a higher whiteness index of 90.26 ± 0.30, whereas HA drying showed 87.04 ± 0.45. The SEM analysis showed the presence of oblong and sphere-shaped starch granules with a smooth surface in the case of RW dried UGBF. The crystallinity of RW and HA dried UGBF were found to be 9.61% and 8.73%, respectively by using x-ray diffractograms. The gelatinization temperature and enthalpy of UGBF obtained by RW and HA drying were found to be 80.92 °C and 2.05 Jg−1K−1; 75.74 °C and 2.64 Jg−1K−1, respectively.
The survival of beneficial microorganisms in kefir powders by refractance window drying was higher at 50°C than other drying temperatures. This suggests that refractance window drying at low temperatures can be used in probiotic-rich products. Cornellian cherry pulp, a rich source of bioactive compounds was dried by both refractance window drying and convective drying. Refractance window drying not only provided a less drying time of minutes but also resulted in better quality in terms of colour, ascorbic acid, and total monomeric anthocyanin content. Additionally, it did not cause the formation of HMF, which is a heat-induced contaminant.
Hybrid dryer energy efficiency is superior to solar (25.6% and 12.0%, respectively) Lakshmi et al. In the production of mango powder with and without the addition of maltodextrin by spray-drying and RW drying. According to the authors, due to the sticky characteristics of the mango pulp, it is important to add maltodextrin in the spray-dryer process, which was not required for RW. However, to produce the final powder it is necessary to adopt a grinding after the RW process when an irregular structure is obtained.

Figure 3 shows the drying curves of guava samples obtained by CD, FD and RW methods. The moisture content of the fresh samples was 8.8 ± 0.7 g water/g dry solid (89.7%, wet basis). Optimization of drum drying processing parameters for production of jackfruit powder using response surface methodology. Effect of drying methods on the physical properties and microstructures of mango (Philippine “Carabao” var.) powder. Mango powder was prepared using three different drying process i.e. All powder samples were examined by Scanning Electron Microscopy using Scanning Electron Microscope operated at an accelerating voltage of 20 kV.
On the other hand, some authors have reported that the diffusivity shows a strong dependence on the moisture , particularly at low moisture contents, as mentioned by Ruíz-López and García-Alvarado . In the yoghurt powders produced by RW drying at 50 °C was higher than those produced by RW drying at 60 °C and 70 °C. Volza’s data of World Window and HSN Code 8419 imports from India is 100% authentic as it is based on actual import export shipments and is collected globally from over 20,000 ports from over 70+ Countries.

Most studies on the RW technique have been carried out with fruits and vegetables in purée or juice; however, this technique is also attractive for drying of fruit and vegetable slices. On the other hand, Nutradry, an Australian company, produces a range of products including lycopene, beta-carotene, spirulina, barley grass, teas and herb blends . Jones patented a method producing a homogeneous dried material from either a mixture of foods or herb and food extracts by using the RW technique. The equipment required for RW drying is simple and relatively inexpensive as compared to freeze-dryers, which generally require large facilities to be economic. For drying a similar amount of product, the cost of an RW equipment is about one-third of the cost of a freeze-dryer, whereas the energy consumed by RW is less than half the energy consumed by a freeze-dryer . Potatoes are a widely consumed staple food and a key ingredient in numerous food products such as French fries, chips, mashed potatoes and various snacks.
During impingement processing, the boundary layer around the product is broken through high velocity air impinging upon the surface. This process increases the heat and mass transfer rate, and allows efficient removal of moisture, baking, curing, toasting and roasting. Nozzle Dry Impingement Ovens reduce processing time significantly when compared to lower velocity convection or through-air systems. According to one embodiment, an apparatus includes a drying belt configured to receive a product to be dried on a first surface of the drying belt, and a heat medium in contact with a second surface of the drying belt. The heat medium is configured to heat the product and is maintained at a pre-determined temperature.
This drying technique outperforms the conventional method due to reduced drying temperature, drying time, energy consumption, and greater quality retention. The researchers have found that results of RW dried potato14, carrot15, tomato16, goldenberry17 and aloe vera18 had maximum quality retention. Considering the advantage of RWD technique, the present study was planned to dry black carrot puree using RW dryer then fermented with freeze dried LAB to produce reconstituted Kanji. Drying is a fundamental process in the food industry, especially for highly perishable foods, such as fruits and vegetables, because they tend to have short durability post-harvest, resulting in economic and environmental losses. The Refractance Window is a suitable technique for fruits and vegetables as it maintains the nutritional quality of the raw material in the dry product.

We produce Infrared assisted Refractance Window Dryers from lab scale to commercial scale. Moreover, we can also design and produce dryers according to your needs. InfraRWD provides better quality in terms of physical and chemical properties. Calín-Sánchez Á., Szumny A., Figiel A., Jałoszyński K., Adamski M., Carbonell-Barrachina Á.