Combine
grapes, lemon (including rind and seeds) and the water in large
saucepan; bring to boil. Reduce heat; simmer, covered, 45 minutes. Stir
in port, crush grapes in pan using a potato masher. Simmer, covered, 45
minutes. Strain mixture through large piece of damp muslin into large
bowl; allow mixture to drip through cloth for several hours or
overnight. Do not squeeze or press the mixture through the cloth as this
will result in cloudy jelly.
Measure the
strained liquid, discard pulp. Allow the correct amount of sugar to each
cup of liquid. Return liquid with sugar to clean large saucepan; stir
over heat, without boiling, until sugar dissolves. Boil, uncovered,
without stirring, about 15 minutes or until jelly sets when tested. Pour
hot jelly into hot sterilized jars; seal while hot.
