Some jam recipes call for liquid pectin and others call for powdered pectin. What is the difference and can they be interchanged? —D.D., Mapleton, Maine
Both powdered and liquid pectin are made from the naturally occurring pectin in apples and citrus fruits. However, they are not interchangeable. Always use the type of pectin called for in the recipe. Usually, powdered pectin is stirred into the fruit and brought to a boil before the sugar is added. Liquid pectin, on the other hand, is added to the mixture after all other ingredients have been brought to a boil.