Many of us may enjoy the bountiful harvest of fresh watermelon,apples,tomatoes,oranges,strawberries,blueberries,raspberries,bananas,pineaple,plums,and nectarines.A mixture of fruits from various sources may contribute to a healthier body.However,fruits contain acetic acid,malic acid, tartaric acid,oxallic acid,lactic acid and benzoic acid. while acids are necessary for digestion and other body reactions,they can be harmful to your smile.