On a recent shopping trip I bought some locally roasted beans from Rwanda, which were labelled "Karenge".
The aroma is delicious, but on opening the bag I immediately noticed light-colored matter clinging to the clefts of the roasted beans (click for close-up):
Upon grinding light-colored flecks are noticeable in their contrast with the dark coffee grounds.
What is this light-colored matter, and does its presence result from shortcuts in the coffee production or processing?
What you are likely seeing is the silverskin of the coffee cherry. Green coffee beans prior to roasting generally still have the silverskin intact/attached. As the bean expands during roasting and the silverskin dries out, it generally comes off. Part of the roasting process is some sort of agitation and airflow to remove this chaff. Depending on the roast level and other mechanical factors, more or less of the silverskin may be removed. On lighter roasted coffee with less expansion you can often see bits of silverskin along the seam on the bean. Some processing methods prior to roasting also remove less of the silverskin, "dry processed" coffee in particular tends to be more chaffy when roasting and may require a longer time agitating or smaller roast batches to remove chaff.
Many of my lighter roasts end up with a bit more chaff than I'd like. Like most anything involving coffee, you can find differing opinions on how much it affects taste.
Do you know whether your beans are "washed" ("wet process")?
There should be no problem with the white part. This is typical of washed coffee beans (vs. the "natural" beans that are, well, not washed, and the same part is then black).
Also, when grinding beans, there is production of chaff that does affect the taste of the final drink. This should be the light-coloured flecks you have noticed. Although part of the chaff is inevitable, you can try to remove as much as possible to get better results. Chaff is a reason why a good grinder can be important.
