With so many different containers, from plain glass jars to branded storage jars, selecting the right one to make a preserve for a gift or to keep for yourself is often a challenge. Selecting the correct method to seal a jar is frequently misunderstood. As a competition judge I often see exhibits with not only a waxed disc and cellophane cover, but also twist-top lids and a fabric or paper cover all on the same jam jar. By following a few simple rules it is possible to bottle and seal preserves confident they will have a long and safe shelf-life.
Marmalade and Jam Jars
Select clear glass jars and twist-top lids. All sizes of jars are suitable, although traditionally, jellies are potted into 225g jars. The lids are made from plastic coating or lacquered metal, similar to those on commercial preserves, available from cookware retailers and online. They are used with jars which have four ridges sloping upwards on the neck. Apply the lid as soon as the hot marmalade, jam or jelly has been potted so that the contents of the jars remain sterile. The lids create a seal between the surface of the sweet preserve and the underside of the lid and ensure that any yeasts and moulds present in the minute space between the surface of the jam and the lid do not survive. Always use new twist-top lids as a re-cycled lid may not provide an airtight seal.
Covers for chutneys need to be both airtight and resistant to corrosion from the vinegar in the recipe. Fill the jars to 5mm from the brim. Always seal the jars with new, plastic lined twist top lids. They are immune to its acidity and also prevent the chutney from evaporating. I have opened many vinegar preserves at competitions sealed with old, un-lined lids, which have corroded and spoilt the contents. It is not a good idea to use a waxed disc and cellophane cover as the chutney will evaporate and the contents shrink. This in turn means it will be dry and the consistency compromised.
Mincemeat and Fruit Curds
Popular to give as gifts, these are not true preserves. Fruit Curds contain eggs and butter, cooked at a low temperature, otherwise they curdle. Mincemeats are frequently not cooked, and if they are, they do not reach a high temperature in the same way as sweet preserves. These two should always be potted into glass jars and covered with a “breathing cover”. This is a close fitting, moisture and vapour- proof disc of cellulose or waxed tissue, and an outer cellophane cover. Place the waxed disc, wax side down. The cellophane cover is put on when the Fruit Curd or Mincemeat is cold. Add a twist top lid as an extra to help with easy storage once the jar is opened and stored in a refrigerator. Bottling Curds and Mincemeat with just a twist top lid is not recommended, as fermentation and exploding jars may well follow.
Kitchen hygiene for Covers and Containers
Keep the stocks of covers and containers in clean storage areas. Jam jars should be sterilised in hot soapy water, rinsing and then dried in an oven temperature of 140°C (275°F) Gas1 for 15 minutes, at the same time as making the preserves, in order to prevent the jars from becoming re-contaminated. New Covers and Containers; twist-top lids and jars can be bought online from Bottle Company (South) Ltd.