I used Vitamix before myself and just soaked grapes and apples in water for 20 minutes or so before putting them into Vitamix together with the skin. Now that my dad has been diagnosed with some form of cancer on upper palate (still waiting for final pathology results at this moment) , me and my siblings are debating if we need to peel off the skins as while some say the skin have lots of good nutrients, others would say all skin need to be off to get rid of pesticides. If skin can stay, what will be the best way to clean them ? Many thanks!