As with all kosher products, kosher wine must conform to strict Jewish biblical laws and be produced under a rabbi's supervision (even the yeast must be kosher). In North America, kosher wine used to be made from acidic Concord grapes, then sweetened with sugar to cut down the acidity. Today's vastly improved kosher wines use standard winemaking methods and grapes but are still an integral part of traditional Jewish ceremonies such as Sabbath kiddush and Passover seders.