Kitchen Corner: Mason Jars

Mason jars are here, there, and everywhere these days. In my home alone they serve as spice jars, cocktail glasses, candle holders, plant pots, and dog treat vessels, and I could keep on going! Aside from Mason jars myriad decorative uses, canning is also making quite the comeback. Over the last few years, as the local food movement has grown in strength, so has our want to keep it going all year long.

Fall is a prime time to get canning. Late harvest fruits and vegetables can be cooked, pickled, jammed, and preserved for months to come. It’s also perfect timing to get a jump on your festive gift list—who doesn’t want to receive a beautiful homemade canned present?

Types of jars

From teeny-tiny, all the way up to 1/2 gal (2 L) sizes, there is sure to be a jar to fit your particular needs. Smaller, wide-mouth varieties are ideal for jams and jellies as they are easier to pour the viscose liquids into. 

Low and high acid

For foods with a high acid content, such as fruits and pickled vegetables, safe canning can be achieved using the water bath method; filled jars are submerged in water and boiled for a specific length of time according to the canning recipe. The high acidity means that the jars do not need to reach a temperature higher than boiling point. Some fruits, such as tomatoes and figs, need to have an acid, (such as lemon juice or citric acid) added to them in order to use the water bath method.

Vegetables, meats, dairy, poultry, and seafood have a lower acid content. Without proper care they can form potentially poisonous spores over time. The jars must be pressure cooked at a temperature of at least 116 C (240 F) for a number of minutes depending upon the recipe. This will ensure the safe shelf life of your preserves. 

Sterilizing

To sterilize your jars, place them right side up into a saucepan and cover with hot water. Place on a rack inside of the saucepan and boil for 10 minutes. If you are higher than 1,000 ft (300 m) above sea level, boil for an additional minute per 1,000 ft.

Put a lid on it!

Just the once though. If you are using Mason jars for traditional canning, the flat part of the lid with the rubber seal can only be used on a single occasion. During the process, the rubber changes shape in order to form an air-tight seal. If you use last year’s lids, you are running the risk of your wares not sealing completely. The glass jars and screw tops remain unchanged and are safe to use as many times as you wish.

A properly sealed lid will curve slightly downwards, and not move when pressed.