What causes tipping in coffee roasting?

Tipping in coffee roasting refers to the browning or darkening of the tips of the coffee beans during the roasting process. The correct answer is related to the phenomenon of heat transfer. Specifically, too rapid heat transfer can lead to uneven roasting, which is what causes the tips of the beans to develop a darker color compared to the rest of the bean.

When heat is applied too quickly, the outer surfaces of the beans can heat up faster than the inner parts. This creates a condition where the outer layer becomes too hot, causing it to caramelize and darken before the inner components of the bean reach the appropriate temperature for even roasting. The result is the visible darkening on the tips of the beans, known as tipping.

In contrast, insufficient moisture, water evaporation, and overtemperature conditions can affect the overall roast quality and flavor but are not the direct causes of tipping. Insufficient moisture might lead to attributes like a lack of body or flavor intensity but wouldn’t specifically cause the uneven browning that characterizes tipping. Therefore, the phenomenon is primarily attributed to the rapid heat transfer that disrupts the normal roasting progression of the beans.