The aerodynamic properties of crop grains influence the selection of the design and operational parameters of equipment. These properties are crop variety specific and moisture dependent. Measurement of terminal velocity is important to determine other aerodynamic properties. A terminal velocity measuring apparatus with vertical tapering rectangular air duct was developed which can measure velocity from 0 to 15 m/s. The sesame (Sesamum indicum Linn.) seeds of variety N-8 were dipped in water to obtain test samples of moisture contents 9.50, 13.46, 18.89, 24.17 and 28.99 per cent. The terminal velocity measured with the newly developed apparatus was found increased from 3.05 to 5.25 m/s with corresponding increase in moisture contents from 9.50 to 28.99 per cent (w.b.), respectively. In other aerodynamic properties, the values of drag co-efficient were found decreased from 2.9 to 0.6 and Reynolds number increased from 3939.9 to 11043.6 with corresponding increase in moisture contents from 9.50 to 28.99 per cent (w.b.), respectively. Simple linear regression equations were fitted to the obtained data to predict the aerodynamic properties of sesame seeds.

Barnyard millet (BM) based hot air puffed product has less crispness. Oven toasting improves the crispness of the puffed, roasted or flaked food products. A ready-to-eat (RTE) puffed and toasted snack food product from BM was developed. Toasting experiments were designed using central composite rotatable design (CCRD) at varying temperature (84-126 o C) and time (10-30 min). There was significant reduction in moisture content, colour and hardness of toasted product with increase in toasting temperature and time whereas there was higher increase in crispness at lower levels but less increase at higher levels of toasting parameters. The influence of temperature was dominant over toasting time for all responses. Reduction in moisture content and improvement in microstructure of the product during toasting resulted in the significant increase in crispness. The process parameters were optimized using response surface methodology (RSM). The quality attributes like moisture content, colour, crispness and hardness of the optimally toasted snack food were 0.046 kg kg-1 dm, 69.79, 18.45 and 362.64 g, respectively at the optimum temperature and time combination of 116.26 o C and 20.23 min, respectively. The total energy content of the BM snack food was 380.74 kcal per 100 g product.

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Barnyard millet (Echinochloa frumentacea L.) is a carbohydrate rich coarse grain which can be used to develop a readyto-eat (RTE) puffed product. Cold extruded dough sheet pieces prepared from barnyard millet flour, potato mash and tapioca powder in the proportion 60:37:3 were steam cooked and then puffed using high temperature short time (HTST) process in hot air puffing machine. The experiments were designed using central composite rotatable design (CCRD) and the effect of process parameters viz. steaming pressure (0-1.43 kg cm-2); steaming time (5-25 min); air temperature (210-250 °C) and puffing time (10-50 s) on the product quality attributes like moisture content, expansion ratio, colour (L-value), crispness and hardness were investigated and optimized using response surface methodology (RSM). The texture characteristics of puffed product were prominently dependent on moisture content while volume expansion was highly dependent on steaming pressure and puffing time. The final puffed product with optimum moisture content (0.106 kg kg-1 dm), expansion ratio (2.06), colour (72.19 L-value), crispness (11.65 peaks) and hardness (480.66 g) was obtained. The optimum process conditions were: steaming pressure, 0.85 kg cm-2 , steaming time, 10.0 min, air temperature, 234°C and puffing time, 39 s. The sensory evaluation of the optimally developed product added with spices to enhance taste, showed the product to be highly acceptable.

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