Cooling after roasting

When you have roasted your coffee beans you need to cool your batch quickly – or it will harm the taste.

From roasting teachers I have heard the rule: cool the roast to below 40°C in 4 minutes.

But I have never explored what difference the speed of the cooling makes for taste. Mike Costaney did and he made a voice memo for my podcast. Listen at Sip 1: cooling the beans.