The drying conditions affect not only the apparent volume, which characterizes the individual particles but also the shape of these particles and thus the bulk volume which, in turn depends on the degree of packing of the material. In this way, studies on dried chokeberry showed that both FD and MVD were found to be the most efficient methods in terms of bulk density reducing it to around 50% when compared to the CD. In addition, the combined CD-VMD, developed to prevent the sample overheating, was also found to be a good option in order to reduce the bulk density of the dried products up to 55% with respect to the convective dried products. This could be due to volumetric heating occurring when microwaves are applied, which results in puffing of the material.
Enhancing Food Processing: Refractance Window Dryer's Role in Nutrient Preservations are very successful at removing moisture from high moisture products that generally vary in solids content between 3% and 70%. Refractance Window Dryers feature modular design which enables the customer to add more modules to the dryer as processing needs increase. The Influence of selected drying methods on the physical properties of dried apples cv. Chen Q., Li Z., Bi J., Zhou L., Yi J., Wu X. Effect of hybrid drying methods on physicochemical, nutritional and antioxidant properties of dried black mulberry. Que, F.; Mao, L.; Fang, X.; Wu, T. Comparison of hot air-drying and freeze-drying on the physicochemical properties and antioxidant activities of pumpkin (Cucurbita moschata Duch.) flours. In order to have an attractive appearance of the final product and to avoid the unpleasant taste of the seeds after drying, the fruits were washed, peeled and depulped.
In this paper, a local fruit-based snack was dried by hot air drying, microwave-assisted drying, and refractance window drying. The study showed that refractance window drying is more advantageous in terms of drying time, chemical properties, and heat-induced contaminants compared to other drying techniques. Moreover, this study also demonstrated that refractance window drying can be used in film type products instead of powders or flakes.
Our machines are built to last and are designed to deliver high-quality results with maximum efficiency. Table 4.Relation between the dry product and the sample thickness. The Tukey test for film type and thickness showed that the mean value of the drying flux was statistically similar for the three thicknesses of each of the films and different for each type of film. The highest drying flux was obtained with PET, followed by LDPE and PP. Fresh green okra pods were purchased from a local supplier and stored at 4 °C prior to the tests. Okra pods were washed and sliced using a manual slicer with 3 mm thickness before drying.
However, this macroscopic approach to quantify the transport of water during the first falling rate period of drying commonly involves the determination of an effective water diffusivity . Chaaban, H.; Ioannou, I.; Chebil, L.; Slimane, M.; Gérardin, C.; Paris, C.; Charbonnel, C.; Chekir, L.; Ghoul, M. Effect of heat processing on thermal stability and antioxidant activity of six flavonoids. Castoldi, M.; Zotarelli, M.F.; Durigon, A.; Carciofi, B.A.M.; Laurindo, J.B. Production of tomato powder by refractance window drying. The total flavonoid content was quantified following the colorimetric method described by Zhishen et al. , using rutin as a standard and performing spectrophotometric reading at 450 nm . The results were expressed in milligrams of rutin per 100 g of sample .
Firstly, it was assumed that the main heat transfer mechanism of RW drying system was thermal radiation via the plastic sheet through a transparent window which was created by the contact of wet material on the surface of the sheet. Another important parameter in a RW drying is air convection. Forced air convection in a RW dryer causes lower product temperature during the process and higher moisture loss values in comparison with natural convection. Recently, refractive window drying has received considerable scientific attention due to its potential to produce high-quality dried products. However, understanding the drying mechanism and comparing it with conventional drying methods are important to expand its potential applications.
So, more research is needed for the drying of solid foods like meat, fruits, vegetables, etc without compromising their quality. Nowadays, efforts are done to combine RWD with other novel processing technologies like microwave, ultrasound, etc., for the pre-treatment of food products. A bottleneck to scaling up the RW drying process is the need for a wide area to dry and thermal exchange and the film’s thickness is kept on the low side, which reduces the processing capacity.
Recently, Refractance Window Drying technique is seen as an advanced method in terms of drying parameters and product properties compared to the negative aspects of existing drying techniques. Refractance Window Drying technology has advantages on many parameters such as scalability, energy efficiency, cost and end-product quality. The RW drying optimized results were compared with tray drying and oven drying (S D Instruments & Equipments, Kolkata) (Ochoa-Martínez et al. 2012; Tontul and Topuz 2017). Mango pulp of 2.50 mm thickness was dried at 95 °C drying temperature using three different drying processes. For tray and oven drying, pulp was spread uniformly in petri dish (150 × 15 mm, Borosilicate) using spreader (Kaur et al. 2017).
Therefore, the hot air reduces the products surface unbound moisture while the microwave energy eliminates the bound moisture from the inside of the product via volumetric heating. Dried apple slices have a good market potential as a raw material in many processed foods and can be an alternative to deep fat fried chips for health-conscious consumers. This work focuses on assessing the efficacy of developed FIR assisted RW drying system in terms of drying time, energy, and quality attributes in comparison with conventional drying methods.
For pulp production, the dragon fruit slices were ground in a mixer and sieved using a 40-mesh size, with the resulting pulp spread out in a thin layer 5 to 8 mm thick. After drying, the texture of the dried product was analyzed using a texture analyzer (TA-XT plus model, Micro-Systems, UK). Then, the dried product was ground into powder using a mixer grinder . The resulting powder was sieved and packed into LDPE pouches for further analysis.
Greater heating in HD, VD, and RWD at a temperature of 60 °C assisted the breakdown of cell components, resulting in a significant decrease in antiradical activity. Table 4 shows the R2 and RMSE values of the best drying model and ANN model. It was observed that the ANN model showed a higher R2 value and lower RMSE value when compared to the best drying model for both drying methods. The ANN model was able to predict the MR for both drying methods with a reasonable level of accuracy. Independent of the parameters used, the prediction capability of the trained ANN model was better than that of the drying models.