It is important to keep high acid food away from the coated tub because there would be a reaction between the food high in acid and the zinc-coated tub. The outcome of the reaction is Zinc salt which would contaminate the food. If the level of the salt is high, this could lead to sickness in most cases.
It is important to keep a high level of food hygiene so they do not meet materials like zinc which would erode and contaminate the food.