Here is an image of white long-grain rice. I mixed 2 cups of rice with a table spoon of canola oil, then cooked it in a microwave oven at high power for 5 minutes to brown it. I then added 4 cups of water and cooked it in a microwave oven at medium power for 15 minutes.
Such dots would not show up if the rice were cooked without browning first. I suspect that the germ (embryo) has higher lipid content than other parts of the rice grain do, absorbing more microwave energy during cooking.
