Quantitative understanding of Refractance Window drying

RW Drying time of pulp was more influenced by thickness of the pulp than by temperature of drying . In the last phase of drying, heat transfer by conduction becomes more dominant and heat transfer to the product slows down (Baeghbali & Niakousari, 2018; Nindo & Tang, 2007; Topuz, Feng, & Kushad, 2009). Due to these advantages, the RW method is a drying technique suitable for foods that are dried in thin layers such as pulp. RW drying is a novel drying technique for liquid and semi liquid foods such as vegetable purees and juices. In a recent paper, Raghavi, Moses, and Anandharamakrishnan reviewed studies on RW drying. In this technique, drying was achieved in a very short time due to effective heat transfer by both radiation and conduction, with no or little effect on colour and nutritive values of dried materials (Tontul & Topuz, 2017a).
The utilization of ultrasonic technology as pre-treatment before FD represents a promising alternative in accelerating the drying process, decreases energy consumption and maintaining quality as compared to the non pre-treated sample. This review summarizes research progress and current studies in ultrasonic as pre-treatment for freeze drying (US + FD) technique. The impact of US + FD on phytochemical, color, texture and micro-structure of food are well summarized. The review also suggests that Revolutionizing Food Drying: The Advantages of Refractance Window Dryer the optimised US treatment parameters are required to improve heat and mass transfer in food samples which help in speed up the drying process and reduction of drying time. Hydrocolloid formulation resulted in superior physicochemical properties of the pestils compared to traditional formulation. While microwave-assisted drying provided higher phenolic content, refractance window drying provided higher ascorbic acid and anthocyanin content, and lower content of 5-hydroxymethylfurfural.

The fermentation process was carried out in 1 L bioreactor with a workload of 800 mL at 37 °C and agitation at 100 rpm for 10 h. The cell count was done after the fermentation process as shown in section Microbiological analysis. Fermentum K73 with and without carrier material, simulation of Gompertz-Arrhenius model (Eq.7). Until now, different species of probiotic microorganisms have been selected according to their characteristics.
It can be achieved by varying drying air temperature, humidity, pressure or even mode of heat input . Intermittent drying can be accomplished by controlling the supply of thermal energy, which can be achieved by varying the airflow rate, air temperature, humidity, or operating pressure. One can also vary the mode of energy input (e.g., convection, conduction, radiation, or microwave) to achieve intermittency . Selection of proper drying conditions is of primary importance for reduced thermal stress during drying and retention of nutrients, flavour, aroma compounds and microstructure of the dried product (Caparino et al. 2012). Refractance window drying of fruit pulp mainly depends upon the drying temperature and thickness of pulp (Ochoa-Martínez et al. 2012; Zotarelli et al. 2015).
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.

Effects of natural convection and forced convection of air in RW dryer was studied by Ortiz-Jerez & Ochoa-Martínez . Pumpkin slices were dried in this study and temperatures were measured at three levels during drying. The most common drying processes used for the preservation of the food materials are conventional thermal drying, which proved to be a high energy consuming process. With the world progressing towards the application of green technology and sustainable methods, the use of alternative energy efficient drying systems are of paramount importance. Fresh white dragon fruit was purchased from a local fruit supplier in the Kokrajhar market, India.
And R.K.K.; software, M.S.; validation, P.K.N. and K.S.; formal analysis, H.D. And R.K.K.; resources, M.S., S.K., P.K.N., and B.S.I.; data curation, H.D. And P.K.N.; funding acquisition, P.K.N. All authors have read and agreed to the published version of the manuscript. The approach that Saikia et al. describe was utilized in order to ascertain the level of DPPH radical scavenging activity.

Thus, in order to develop high quality dried products besides retaining its color and other functional properties it is also necessary to assure a proper rehydration. Drying methods influence the density, porosity, and sorption features of the product thus, the election of drying methods is essential in order to produce high quality product both dried and rehydrated. Consequently, reduced hydrophilic properties are developed due to the cellular rupture, which is irreversible and results in an integrity loss and dense structure formed by broken down and shrunken capillaries. All of this obstruct the water absorbance and so the rehydration. During rehydration, the dried product suffers numerous internal structure changes i.e., moisture, porosity, volume etc. changes.
Generally, a nonlinear decrease in moisture content with drying time was recorded for all drying methods. From an average moisture content of 2.185 g/g of dry matter, the samples were reduced to 0.01 g/g of dry matter after 1.42, 21, and 27 hours of effective drying for RWD, oven, and solar drying, respectively. Recent studies concerning dehydration of agricultural products using vacuum-microwave technique showed that the most promising method is combined drying which ensures high quality at the lowest possible energy consumption. Research, development, and innovation are carried out in the food processing, especially in fruits, vegetables and aromatic herbs. Nowadays, consumers are demanding novel and healthier ready-to-eat products with long shelf-life and dehydrated products meet these criteria.
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.

Interpretation of results was performed according to CLSI standard. Polymerase chain reaction was used for determination of mec genes. Fifty samples from 70 tested were positive for Staphylococcus spp. In 30% of the isolated staphylococci, the growth was observed on selective media with cefoxitin as well as on MRSA2 Agar.