Intolerance. Lemon yellow is a food additive, also known as E 102, which is usually used to increase the color of food. Lemon yellow is not alkali-tolerant, that is, it will decompose in alkaline environment, leading to discoloration or shedding. Therefore, when making alkaline food, lemon yellow should not be used as colorant. It should be noted that in acidic environment, lemon yellow is relatively stable and not easy to decompose. Therefore, lemon yellow can be considered as a colorant when making acidic food. However, because lemon yellow may cause allergic reaction to some people, the amount of lemon yellow used in food should be controlled within a safe range and follow relevant laws and standards.