For most Americans, grape juice is an occasional treat. For Orthodox Jews, it is an obligation.

Orthodox Jews bless and drink a cup of wine three times on the Sabbath and four times at each of the two Seders for Passover, which will begin at sundown on Monday. Parents often buy grape juice so the children can accustom themselves to fulfilling the commandments. And since Hasidic and other ultra-Orthodox families typically have six, seven or more children, that’s a lot of grape juice.

Welch’s, the American titan of grape juice, has noticed. It has flooded the Orthodox market, having made its intentions clear last year when it teamed up with the kosher colossus Manischewitz. This year, Welch’s Manischewitz demonstrated that it really meant business by turning out juice with an additional kosher certification from a panel of exacting rabbis from the rigorous Hasidic and ultra-Orthodox communities.

“You’re getting two powerhouses coming to this market,” said Sara Stromer, the assistant brands manager for Manischewitz, which is supplying Welch’s with its expertise in distribution to the kosher market.

But in doing so, the almost 150-year-old Welch’s, whose name is practically a synonym for grape juice, and the 129-year-old Manischewitz, the world’s largest matzo manufacturer and a kosher wine and food producer, have set off a fight with the long-reigning emperor of kosher grape juice, Kedem.