Onion slices were dried in a single layer of thickness varying from 1 to 5mm in the temperature range of 50–70°C in a laboratory scale vacuum dryer. The effect of pretreatment, drying temperature and slice thickness on the drying kinetics... more
Onion slices were dried in a single layer of thickness varying from 1 to 5mm in the temperature range of 50–70°C in a laboratory scale vacuum dryer. The effect of pretreatment, drying temperature and slice thickness on the drying kinetics of onion slices was studied. Four thin layer drying models namely Lewis model, logarithmic model, Page model and Fick's law
Onion slices were dehydrated under vacuum to produce good quality dried ready-to-use onion slices. Colour development due to non-enzymatic browning and flavour loss in terms of thiosulphinate concentration was determined, along with... more
Onion slices were dehydrated under vacuum to produce good quality dried ready-to-use onion slices. Colour development due to non-enzymatic browning and flavour loss in terms of thiosulphinate concentration was determined, along with moisture content and rehydration ratio. Kinetics of non-enzymatic browning and thiosulphinate loss during drying was analysed. Colour change due to non-enzymatic browning was found to be much lower in the case of vacuum dried onion, and improved flavour retention was observed as compared to hot air dried onion slices. The optical index values for non-enzymatic browning varied from 18.41 to 38.68 for untreated onion slices and from 16.73 to 36.51 for treated slices, whereas thiosulphinate concentration in the case of untreated onion slices was within the range of 2.96-3.92 μmol g
Conditioning of cashew kernels before peeling is done to loosen the peel of the kernel and make it fragile enough for its easy removal without damaging the kernel. Conventionally hot air conditioning is done at 70 °C for 6-8 hour. Results... more
Conditioning of cashew kernels before peeling is done to loosen the peel of the kernel and make it fragile enough for its easy removal without damaging the kernel. Conventionally hot air conditioning is done at 70 °C for 6-8 hour. Results obtained from Thermogravimetric analysis (TGA) study suggested thermal stability of cashew kernels up to 268 °C. Rapid conditioning is possible by infrared (IR) heating at 160 °C as alternative of conventional hot air conditioning. This study was carried out to investigate changes in properties during conditioning of cashew kernels. Proximate composition analysis showed that both conditioning treatments, hot air as well as IR, reduced the kernel moisture content significantly in comparison to raw kernels. Gap between kernel and peel, an important parameter determining the peelability of the kernel after conditioning, after the two conditioning treatments, was comparable having no significant difference at 5% level of significance. Thermal propertie...
ABSTRACT Bell pepper has high commercial demand based on its aromatic, coloring, and flavoring properties. Drying of Bell pepper under the Dehumidified Air Drying condition is a very effective preservation technique. Dehumidifier is used... more
ABSTRACT Bell pepper has high commercial demand based on its aromatic, coloring, and flavoring properties. Drying of Bell pepper under the Dehumidified Air Drying condition is a very effective preservation technique. Dehumidifier is used to control the humidity of air entering into the system. It dries the air by physical adsorption. It directly affects the water activity of the material (up to values where microbial activity and other reactions are inhibited) and maintain the texture, mechanical properties, nutritional values, physical properties, etc. The dried bell pepper is used in food mixtures, salad dressings, instant soups, frozen pizzas and many other convenience foods. The present study is focused on the effect of pretreatments on the drying characteristics. The sample were hot water blanched (95 °C for 5 min) and treated with 1% Sodium bicarbonate. The acceptability of nine kinetic models selected from literature for the drying of fruit and vegetables was determined by ap...
ABSTRACT A laboratory microwave-vacuum dryer was used to investigate the drying behavior of grapes under different combinations of power and vacuum levels. Fresh grapes procured from local market were used for the present study. Before... more
ABSTRACT A laboratory microwave-vacuum dryer was used to investigate the drying behavior of grapes under different combinations of power and vacuum levels. Fresh grapes procured from local market were used for the present study. Before drying, grapes were pretreated with solution of sodium hydroxide and ethyl oleate at 80 oC for 30 seconds. Grapes with an initial moisture content of 83% (w.b.) were dried up to a final moisture content of a 15.5±1 % (w.b.). The effect of process variables, namely microwave power (100, 110, 120, & 130 W), pressure (200, 400 & 600 mm Hg), were studied on the drying characteristics viz. drying rates, moisture ratios, Effective diffusivity & ln MR, of fresh grapes and quality attributes like color, texture, rehydration ratio of dehydrated grapes. Microwave-Vacuum drying resulted in 70 to 90 % reduction in the drying time and the mean effective moisture diffusivity in microwave-vacuum drying process was found 8 to 10 folds higher as compared to air-drying...
