Pineapple Jam - cooking recipe

Ingredients

1 (20 ounce) can crushed pineapple in syrup, undrained
1 (1 3/4 ounce) box Sure-Jell, fruit pectin
1/2 teaspoon butter (optional) or 1/2 teaspoon margarine (optional)
3 cups sugar, measured into separate bowl

Preparation

ADD enough water to undrained pineapple to measure 3-1/4 cups. Place in 6- or 8-quart saucepot. Stir in pectin. Add butter to reduce foaming. Bring to full rolling boil (a boil that doesn't stop bubbling when stirred) on high heat, stirring constantly.
ADD sugar; stir. Return to full rolling boil and boil exactly 1 minute, stirring constantly. Remove from heat. Skim off any foam with metal spoon.
LADLE quickly into prepared jars, filling to within 1/8 inch of tops. Wipe jar rims and threads. Cover with 2-piece lids. Screw bands tightly.
Process 5 minutes in a hot water bath. Remove jars and place upright on towel to cool completely. After jars cool, check seals by pressing middle of lid with finger. (If lid springs back, lid is not sealed and refrigeration is necessary.).