Spotting a bad bean

I am a home roaster and get my beans from sweetmarias. I was reading some articles on using the aeropress and saw a few people talking about selecting good beans and throwing out ones with a defect. How do you spot a defect in a bean?

You can look at this. It seems to be a pretty good compilation of bean information.

http://www.zecuppa.com/coffeeterms-bean-defects.htm

I heard about people selecting beans without any roasting defects (no tipping, cratering, burnt/scorched, etc.) when trying to brew the perfect cup.

With a burnt bean it is pretty obvious that the taste is going to be off, but I am not sure how craters or milder defects will impact the cup when mixed in with other beans.

The two on the left look like a defect. The other two with the craters are beans that blow off the chuck when the go to second crack. I dont think they are a bean with a defect

I believe they are called quakers? Anyway, its the ones that are much lighter than the others after roasting that I pick out.

Is your concern more about defects in green coffee or those that happen during roasting? I believe I introduce more defects during my roasting than the farmer did in their growing and processing. ;-) I have only had one truly bad or defective green coffee, which was due to bad processing and affected the whole batch. All my other green bean purchases were somewhere between good and excellent. I have seen some batches that have more small bits or shrivelled up beans than the others, but I think it has a minor affect on the taste.

I am interested in spotting the bad ones after I roast

I usually pull out the quakers (off colored, under developed beans) and any beans that look scorched. That's about all I do after I roast...I don't worry all that much about it since I'm roasting for my family alone and I really don't think my taste buds are that refined.

Likewise, I rarely do any after roast inspection to remove beans. The wire drum of the Behmor helps to screen out smaller bean defects either before or during the roast. If I happen to spot a charred bean or a really off colored bean I will throw it out, but most of the time just grind and brew, defects and all.