Details of the surface of a puffed rice grain. Puffing - the sudden expansion of the rice grain volume - resulted in the disintegration of the rice grain coat into small fragments dispersed on the grain surface now composed of a solid rice starch foam. Enhanced SEM. Image width: 2060 micrometers. Magnification: 48.5x if the image is printed 10 cm wide. Bar: 500 micrometers (0.5 mm).