A jelly bag is a piece of kitchen equipment used to strain fruits, typically for use in jelly, to separate the juice from seeds and other solid materials. While often commercially available, a number of substitute home methods for straining have been created and used by jelly makers over the years. These substitutions include using unbleached muslin, old pillowcases, and even mesh cloth such as pantyhose. This bag will typically be used with a stand, often a tripod stand or bending stand that can attach to a bowl, though some can be hung from hooks above a bowl.
Often made from unbleached muslin, a jelly bag can be made from other materials as long as they are fairly thin and can allow liquids to pass through while reserving solid substances. These bags are usually used in the early part of making jelly, with fruit that has been cooked slightly or smashed. The fruit is then placed inside the bag and the bag is either suspended over a bowl or connected to the bowl through some type of stand. This allows the liquid fruit juice to slowly drip from the sheer cloth, and the solids such as seeds, skin, and meat of the fruit remain in the bag. For best use, the fruit should be left for a long time, such as overnight, and not squeezed through the bag.
A jelly bag is used to produce jelly, though it can be used for any type of application where someone wishes to separate solid matter from liquid. Someone making homemade ketchup or spaghetti sauce can use this bag to strain the liquid from crushed tomatoes, while keeping the seeds and skin separate. Home jelly makers have often bragged about the clever substitutions they have found when a traditional jelly bag was not available. The small size of some bags also tends to make them sometimes inappropriate for some uses, especially when a large quantity of jelly is being made.
Among the more popular substitutions for this bag are new pantyhose or an old pillow case. Old pillow cases are often worn fairly thin from daily use and frequent washings. This means they can typically allow liquids such as juice to pass through, while keeping solids contained within the pillow case. New pantyhose are typically of such a fine mesh, and lack large tears, that they will function much like a jelly bag. Either substitution can be suspended from a hook or similar fastener over a large bowl to collect the juices.