Strawberry Jelly

This is less a recipe than a two-stage strategy: bank the strawberry flavor in June, then borrow the setting power of crab apples in the fall. The chemistry is sound, but the original leaves the proportions and the storage step to the cook's judgment.

• Why it worksStrawberries are low in both pectin and acid, which is why straight strawberry jelly so often stays syrupy. Crab apples are high in both, so the finished mixture sets on the strength of the apple while tasting of the berry.
• The syrupOne pound of sugar to one pint of strained juice is roughly 2 cups sugar to 2 cups juice. Heat until the sugar is fully dissolved and the syrup just reaches a boil; longer cooking darkens it and dulls the fresh berry flavor you are trying to preserve.
• Storing the syrup"Seal and set away" reflects a period assumption that a hot-filled, heavily sugared jar keeps on a cellar shelf. Current practice is to process filled half-pint or pint jars in a boiling-water bath for 10 minutes, or simply to refrigerate or freeze the syrup until crab-apple season. Surface mold is the likeliest way an unprocessed sealed syrup goes wrong.
• "Half as much" — of what"Half as much" -- of what -- The instruction means half as much crab-apple jelly as syrup, measured by volume: 1 cup of jelly to 2 cups of syrup. The recipe frames this as something done while making crab-apple jelly, so it may mean the jelly just cooked rather than a jar off the shelf; either will work, provided it is strained jelly and not raw juice.
• Judging the set"Boil together a few minutes" is vague because it depends on how firm your crab-apple jelly was. Boil to 220F (8F above the boiling point of water at your altitude), or test on a chilled saucer until the drop wrinkles when pushed.
• SkimmingReboiling two cooked preserves together can throw some foam. Skim it off just before jarring, or the finished jelly may be cloudy rather than clear.
• YieldA pint of strawberry syrup plus a cup of crab-apple jelly gives roughly three half-pints, a little less after boiling. Fill hot, sterilized jars and process 5 minutes in a boiling-water bath. If you would otherwise seal jelly under paraffin, as was common when this was written, note that paraffin is no longer recommended.
• If you have no crab applesTart cooking apples, cored and cooked with skins on, give a weaker but usable pectin stock. Commercial liquid or powdered pectin does the same job, but follow that package's sugar ratio rather than this one, since the ratios are not interchangeable.