What you are seeing is the root tips looking for something to anchor in"dirt,growing medium".They generally do not turn a color.If you are looking for a good sprout for eating that is high in protein then check out buckwheat grouts.A great site for info. on sprouting is sproutpeople.com the info. is solid but the seed prices are way to high.Sunlight exposure should not be a problem but less is better during the initial sprouting phase.Are you making bread or what are you going to do with the sprouts?