God provided liquid oxalic acid a long time ago......red wine, concord grape juice, carrot juice, beet juice, cranberry juice, prune juice, all vegetable juices!! How about the juice from strawberries, blueberries, blackberries, and raspberries? Not all bottled juices are manufactured by use of giant electric juicers. Many use hydrolic presses. Only suggestion.....avoid the juices that contain citric acid . That ingredient alone will decompose as much oxalic acid as a microwave. As the website www.coljoe.com indicates, Hains Pure Foods Hollywood carrot juice is probably one of the best. One 12 ounce can is equal to 2 pounds of carrots and is simply pressed. This company canned a product without feeling the need to better that which was already perfect. The question to ask is, "Why does man feel the need to better what God has already perfected?"