Hello when one add coffee beans to there beer after it fermented how would one sanitize the coffee beans before adding them ??.
You don't. By the time the ferment is over, the alcohol and low pH pf the beer protect it. I have never sanitized the beans and it's never caused a problem.
not dry beaning but applicable http://brulosophy.com/2018/07/09/brewing-with-coffee-hot-vs-cold-brew-exbeeriment-results/