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Green mature “amrapali” mango fruits were stored at 12 ± 0.2°C under rapid controlled atmosphere (RCA) with various combinations of two levels of oxygen (2 or 5%) and 3 levels of carbon dioxide (4, 6 or 8%) to investigate the effect of RCA on the production of aroma volatiles both in the raw fruit and after ripening at 21°C for 5 days. The RCA conditions were established by flushing calculated amounts of liquid nitrogen (LN2) into the storage chamber. Whole fruit samples were removed from storage at weekly intervals and analysed for volatiles with a headspace purge and trap system. Terpene hydrocarbons were found to be the dominant group for the raw fruits while esters were the major component of the volatiles for the ripe fruit. Production of aroma volatiles on ripening was found to be higher in the freshly harvested fruit, with lower level of O2 and elevated level of CO2 inhibiting production of volatiles especially for hydrocarbons and esters. Mathematical equations using polynomial regression were found to closely predict the values of total aroma volatile classes. The RCA stored ripened fruits were found to be sensorily acceptable, even though it scored lower compared to control fruits, the difference was not significant.

Convective air drying studies were conducted on a laboratory model thin layer dryer. The parameters studied were 70-150°C drying air temperature, 0.5-2 m/s air velocity and 5-20 cm grain bed depth. The effects of mixing, tempering and multistep drying process on milling quality were evaluated. Mixing, tempering, multistep drying and control of grain temperature enhanced the milling quality while reducing the drying time and specific energy requirement. To achieve maximum head yield, minimum specific energy and minimum drying time, the optimum process parameters were grain bed depth 7-10 cm, air velocity 0.55-0.68 m/s and drying air temperature 112-116°C. This combination gave 65-68% head yield and specific energy consumption of 8.5-10.7 MJ/kg of water removed.