Garg, M. K.Rushikesh2016-10-282016-10-282012http://krishikosh.egranth.ac.in/handle/1/82697A study was undertaken on osmotic-convective and convective drying of aloe vera cubes to investigate mass transport process. Fresh aloe vera leaves were washed and cut into 15 × 15 × 15 mm cubes. These cubes were osmotically dehydrated in different concentration (30, 40, 50, 60 and 70 ºBrix) and process temperature (30, 40, 50, 60 and 70 ºC) with syrup to fruit ratio (3:1, 4:1, 5:1, 6:1 and 7:1) for 4 h duration of osmosis. Central composite rotatable design was used to analyse osmotic dehydration process. The osmosed and unosmosed aloe vera cubes were dried in heat pump dryer at 30, 40, 50 ºC and tray dryer at 50, 60, 70 ºC drying air temperatures. The effect of process parameters during osmotic dehydration such as duration of osmosis, sugar concentration and process temperature of syrup on mass reduction, water loss and sugar gain were studied. It was found that the mass reduction and water loss increased with increase of sugar concentration and process temperature while solid gain decreased with increase in sugar concentration and process temperature. It was found that osmosis as a pretreatment prior to convective air drying was able to decrease drying time. Drying curves were affected by the drying air temperature and osmotic dehydration as a pretreatment. Increase in the air temperature caused a decreased in the drying time. It was observed that drying rate increased with increase in drying temperature from 30°C (HPD) to 70°C (tray) and constant rate drying period was absent throughout the drying process of aloe vera cubes dried under all drying air temperatures. The moisture diffusivity varied in the range of 1.37E-08 to 4.56E-08 m²/s and 9.11E-09 to 5.18E-08 m²/s during convective drying of unosmosed and osmosed aloe vera samples depending on the drying air temperature. The values of rehydration ratio of conventionally hot air dried sample were higher than the osmo-convective dried aloe vera samples. The osmo-convective dehydrated samples were found more acceptable than convective dried ones. Air temperature and pretreatment as osmotic dehydration had a significant effect on sensory evalution.enDrying, Aloe, Dryers, Irrigation, Sugar, Sampling, Concentrates, Evaporation, Solutes, ProductivityThesis