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This present research aimed to investigate the effect of slice thickness and concentration of the osmotic solution on mass transfer kinetics, the color profile of osmotically dehydrated pineapple slices, and product quality characteristics of osmotically dehydrated microwave-dried (ODMWD) products. Three slice thicknesses (0.5, 1, and 1.5 cm) and three concentrations of osmotic solution (40, 50, and 60 °Brix) were used. The mass transfer kinetics (moisture reduction behaviour, weight loss, solid gain), physicochemical properties (color, TSS, pH, titratable acidity, vitamin C, and total sugar), and total phenolic content of pineapple slices were analyzed. During osmotic dehydration, the moisture reduction behaviour of 0.5 cm slices was faster in all osmotic solutions, whereas water loss and solid gain were higher for all slices treated with 60 °Brix. Both slice thickness and concentration of the solution significantly affected the color of OD pineapple slices. For ODMWD products, total soluble solids (TSS), pH, ascorbic acid content, total sugar, and total phenolic content increased for all slice thicknesses with an increase in osmotic solution concentration, whereas titratable acidity exhibited the opposite result. The rehydration ratio was higher in 0.5 cm slices for all solution concentrations. According to the finding, pineapple fruits can be dehydrated by using 60 °Brix solution concentration with 0.5 cm slices for making dehydrated pineapple fruit, and osmotic dehydration followed by microwave drying of pineapple fruit could be used for value-added processing products.

In this paper, the effect of two options (first option: fluidized bed drying (120–160 °C) + sun drying; second option: fluidized bed drying (120–160 °C) + again fluidized bed drying (65 ± 2 °C)) of two-stage drying on kinetics, energy consumption, quality of dried maize as color, nutritional properties, and hardness was evaluated to assess the drying performance. First stage drying for both options was executed by FBD at 7.0 cm bed thickness within the temperature range of 120–160 °C for 1.5–4 min. Then, the samples were tempered for 45 min in a closed container after completion of first stage drying. Second stage drying was then done by sun drying method (temperature: 33–36°C, RH: 52–65%, air velocity 0.4–0.6 m/s) for first option while for second option, it was accomplished again by FBD (65 ± 2°C). Drying time was shorter in the case of second option (2.23 h) than first option (4.98 h). Effective moisture diffusivity was found higher in both options of two-stage drying (10.5 × 10−09 m2/s to 63 × 10−09 m2/s) than control drying. Specific energy consumption was lower in first option compared to second option. Color of dried maize in two-stage options deteriorated markedly. However, nutritional qualities of dried grain for two-stage drying technique were similar to control sample. Hardness of the two-stage dried maize was lesser than control product. The two-stage drying options of maize drying instead of conventional sun drying method can be considered an alternative drying technique for the commercial maize drying industries.

Drying is an important issue for all paddy-producing countries in the world. Paddy drying facts and figures in industrial LSU (Louisiana State University) dryer for the major rice processing areas ...

Evolution of energetic and exergetic performance is an important concern for selecting suitable dryer for any drying process. This paper attempts to observe performance evaluation in terms of energ...

Suitable drying technique and energy efficient dryer are important concerns for drying of high moisture paddy. In this study, a small scale mixed flow dryer (MFD), with presenting systemati...

Investigation of exergy transfer is an important aspect for all grain drying industry. Exergy transfer of rice husk fired cyclonic furnace assisted recirculating mixed flow dryer (MFD) equipped with a heat exchanger, was sought in this study. A cyclonic furnace (CF) having capacity 0.5 MW and recirculating MFD were designed and developed to investigate exergy transfer during grain drying. Efficiency of furnace was determined to quantify performance of CF for industrial grain drying system. Exergetic efficiency was also thoroughfare performed for the developed CF, air mixing chamber (heat exchanger) and MFD. Thermal efficiency of the CF varied from 68.96 to 87.01% during drying of high moisture maize grain. Exergy efficiency of the CF, heat exchanger and drying chamber marked between 58.8 and 63.5%, 74.6–93.29%, and 3.03–21.9%, respectively. Exploration of exergy inflow persist between 53.32 and 60.51 kJ/s and 7.58 to 9.81 kJ/s while exergy outflow ranged between 7.58 and 9.81 kJ/s and 1.52 to 3.10 kJ/s, respectively for heat exchanger and drying chamber. Results based on exergy losses indicates that 44.01–51.54 kJ/s and 5.87–7.50 kJ/s of exergy is just loss through heat exchanger and drying chamber, respectively. Exergy improvement potential and sustainability index varied between 1.02 and 1.80 kJ/s and 1.17–1.40 kJ/s, respectively. Quality of final product is in acceptable range as color difference of dehydrated maize kernel varied from 9.19 ± 0.46 to 17.05 ± 0.13. Exergy results indicate that CF can aptly be applied for grain drying industry in commercial scale.