Not credible. Although I am not an expert, I am a native of Aksu. The pulp in the center of the sugar-heart apple is high in sugar content, and the color is rock sugar color, which has a clear dividing line with the white pulp in the periphery, and the outermost layer is wrapped with the peel. Even at high temperature, sugar is difficult to volatilize. But if the storage temperature is too high or the storage time is too long (my family can only store it until March and April), the sugar core will turn black, which I personally think is bad. Some apples will have small or no sugar centers because of insufficient light time or other reasons. The skin of Aksu rock candy apple is bright yellow and red, and the best one is the one that seems to have red and yellow stripes and tastes hard.