It can. Heating yogurt to high temperatures destroys the beneficial cultures. To prevent this, never add yogurt directly to a boiling or extremely hot mixture. Instead, stir a few tablespoons of the hot food into the yogurt, warming it gradually. Then stir the warmed yogurt into the hot mixture. Do this near the end of the cooking process, so the yogurt won't be heated for a long time. If the temperature is higher than 120° F, as it is in baking, the live active cultures will not survive, but the yogurt will still provide valuable nutrients such as calcium and protein.