The boiling water bath method (also known as ‘water bathing’ or ‘hot water bathing’) is where you fill clean jars with high acid contents (such as tomato relish, pickled zucchini, strawberry jam), seal with a preserving lid, and submerge under water, then bring to 100°C (212°F) for a required amount of time. This time depends on the contents inside the jars, and the size of the jars.
The ‘high acid’ contents means an environment in which many microorganisms which spoil food or make it unsafe, are unable to survive. Heat destroys any food spoiling/ foodborne illness microbes which may be present. The processing also forces oxygen from the jars, creating a vacuum (anaerobic) environment, which inhibits survival or growth. Then as the jars cool after being removed from the water, a vacuum seal is created, which prevents recontamination and air entry.
- many fruits (to use in desserts, sauces and baking)
- jams, conserves and fruit preserves
- relish, chutneys, salsas
- passata, pasta sauce or whole tomatoes
- other sauces (to use as condiments, or as meal-bases or flavour enhancers in casseroles, stews, risotto, pizza sauce etc)
- pickled vegetables (bread and butter pickles, dill cucumber pickles, pickled jalapenos etc)
- It can be an affordable way to get started, if you use ‘reclaimed’ jars (with new screw/ twist on pop-top lids), a big stock pot you already own or get one second hand, and other gear you already have on hand.
- Easy to moderate difficulty level
- Moderate prep, and process times of 10 to 20 minutes, plus time to sit overnight
- No need for refrigeration or freezing to keep foods long term
- A wide range of recipes available that have been tested by ‘food preserving authorities’
- Need space to store the equipment in between uses, and a dark, cool pantry or cupboard, with even temperature range, to store all your bottles of preserves
- Takes time – prep of food and jars, the processing time, cooling down, labelling and storing
- Easy enough process to follow, but does take some time spent learning the essentials
- Cost of equipment, especially if buying purpose built canner, jars and equipment
You can use specifically designed preserving equipment and jars, of which there a numerous brands used around the world. Or you can use equipment you already have, or can buy second hand, to reduce costs. Please ensure your equipment and jars are in good condition before each preserving session.
You will need:
- large stock pot (tall enough for the filled jars to be submerged whilst the water is boiling) OR a purpose-built boiling water canner (which should come with a canning rack)
- food preserving jars and lids – I mostly use Ball Mason jars, I do use Fowlers Vacola jars, and on occasion, reclaimed jars
- jar lifter/ tongs (I highly recommend the Ball Secure Grip Jar Lifter tongs, found at Big W or online).
- food funnels (plastic, metal, or collapsible, I use one like this)
- bubble remover, or long skewer (bamboo is preferable over metal), or chopstick
- timer, clean tea towels/ oven mitts (silicone), labels
A common home preserving concern is that people are not sure how to tell if their boiling water bathed preserves are safe. I get it, it took me a while to build my confidence with food preserving. If you followed the processing steps correctly, used high acid ingredients (pH less than 4.6) and achieved and maintained a seal, your product can be considered safe to consume.
When you go to open and use a jar, visually check the jar before opening. If the lid has lifted or become unsealed during storage, the contents should be disposed of carefully, and the jar/ ring cleaned thoroughly.
Note: Do not taste the preserves in a jar that has lost it’s seal, to see if they are OK. Some bacteria that cause foodborne illness may not have a smell or taste, or have any obvious signs! You may be unwittingly exposing yourself to unsafe food during your ‘taste test’, or worse, the lack of bad taste may wrongly reassure you, and you eat all the preserves and get sick. Jars that have become unsealed during storage must be presumed unsafe.
If there are obvious signs of food spoilage which has affected the smell, colour or appearance, the contents should be disposed of carefully, and the jar/ ring cleaned thoroughly.
Signs of food spoilage include the presence of mould, or yeast growth, bubbling gases, cloudiness, leaking, fermentation, sliminess and bad smells, or there may be pressure build up under the lid, making it convex instead of concave. If this has occurred, dispose of the contents carefully, then fully clean the jar.
STORING YOUR BOTTLED PRESERVES
Label, date and store your jars in a cool, dry place with temperatures between 10 to 21° C. Avoid cupboards next to ovens, dryers or other areas that may have fluctuating temperatures. We created a large preserves pantry in our ‘linen’ cupboard, by reducing the amount of unnecessary stuff in there, and moving blankets to cupboards in bedrooms. Other people with limited cupboard space may use plastic boxes with wheels that slide under beds.
Check out my free preserving labels to download and print.
You may have read advice to not store your Ball Mason jars with their screw bands on many preserving websites, mainly said as it can ‘hide’ any lids that become unsealed during storage, or the lids may rust. However, the Ball Complete Book of Home Preserving (2006, p.418) states that after washing & drying the screw bands, ‘If desired, screw bands may be loosely reapplied to jars’.
HOW LONG DO THEY LAST IN STORAGE?
Nutrition can be maintained for up to 1 year, though in terms of safety, the theory is that as long as the seal is maintained then it would still be safe to eat. Check the recipe you used for any specific timeframes.
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