Nutritionists advise eating fruit 2-3 hours after a meal, if you want to eat an apple or a banana right before and right after a meal, then be prepared to face heartburn, bloating and an unpleasant feeling of acidity. This is because the enzymes needed to digest fruits are very different from the enzymes needed to digest the rest of the food.
Any type of heat treatment of fruits deprives them of a certain amount of nutrients. So minimize the consumption of packaged juices, candied fruits, jams, compotes - there is practically no benefit in them, but there is plenty of sugar and calories.
Although citrus fruits like lemon and grapefruit seem acidic, they produce an alkaline effect in the body. Just like all other fruits. Therefore, if you are worried about high acidity, then the question here is most likely not about fruits. Maintaining normal levels of alkali in the body is the key to good health. If you want to detox the body, then arrange yourself a two-day unloading on fruit.