Although generally fruits and vegetables are considered kosher, grape juice, wine and their derivatives are an exception to this assertion. Because wine was used primarily for sacramental purposes in ancient times, the Rabbis wanted to prohibit consumption of wine that possibly was used for pagan practices. Therefore they enacted laws regarding wine production. Specifically, all grape products and their derivatives must come from wine that has been supervised from start to finish. Only these may be certified and approved as kosher. In addition, other food ingredients derived from grape or alcohol distilled from wine and its derivatives must have special supervision. This would include grape based colors, brandies, and wine and balsamic vinegars. Artificial grape flavors however, generally contain no grape derivatives and can easily be certified kosher.
The production of kosher meat, poultry, fish, wine and cheese involve particularly labor intensive requirements. Consequently , they generally are manufactured and sold exclusively to the kosher consumer rather than the general market. The additional cost of these special productions is passed on to kosher consumers who are willing to pay a premium for these products. Most other items, e.g. baked goods, beverages, cereals, confections, industrial chemicals, snack foods, and food ingredients not derived from animal sources, qualify for kosher certification with minimal, if any, disruption in normal operating procedure.