Preventing food waste part 2 - open-kettle bottling basics
This week I have been making vast amounts of vegetable soup and bottling it. (The op-shop I work at also has a food bank, and I take home some of the produce that needs to be used ASAP, cook it up, and bring most of it back to the food bank.)
Why bottle?
I used to keep most of my bought-in-bulk perishable food in the freezer, but the trouble with that is the limit to freezer space and cost of the electricity it takes to keep them. Plus, any power outages of more than a few hours will risks the loss of the entire contents of the freezer, unless there's time to cook everything up in order to re-freeze it.
I've also written about dehydration, which works on the same foods open-kettle bottling does, but for me personally, I use dehydrated vegetables differently to fresh or frozen ones.
Bottling is shelf-stable, and the contents last months or even years, depending on what they are. The food can be stored anywhere, not just the pantry: put them in boxes under the bed, in high cupboards that are too hard to reach for frequent-use items, or even in the garage or in the crawl-space under the house - anywhere cool and dry.
Equipment
The great thing about open-kettle bottling is that it doesn't need any specialised equipment! All you need is:
- Regular cooking pot, to cook the food in (a stock pot allows for a larger batch, but any pot will do)
- Glass jars with metal lids, to bottle into (re-using ones from bought products such as pasta sauce, mayonnaise, jam, pickles, is fine and very common)
- An oven, kettle, or large pot, to sterilise the jars and lids
- A ladle
- A large funnel (optional, but very helpful for avoiding mess) - can be made from the cut-off top of a plastic bottle, which both is free and has a larger mouth than most kitchen funnels
- A tea-towel or oven mitt, to hold the hot jars
- Stick blender (optional)
What not to bottle
Open-kettle bottling is NOT suitable for meat, dairy, or anything with lipids (fats and oils). So don't saute your onion in oil, or include avocado or coconut. It apparently is possible to bottle meat etc by pressure-canning, but I have not yet learnt to pressure-can, so I can't comment on it.
The food needs liquid - either the food itself (pasta sauce, jam, soup) or liquid surrounding it (pickles, stewed fruit). Without sufficient liquid, there won't be enough pressure to seal the jars.
Open-kettle bottling is great for pickles, jam and jellies, pasta sauce, stewed fruit, and vegetable soup. Almost any vegetable can be pickled, and almost any fruit can be made into jam.
Intact jars
Ensure your jars do not have cracks in the glass. Ensure the lids have no rust or holes, and are not bent out of shape. (I've seen people open difficult jars by stabbing the lid with a sharp knife, or by banging the edge of the lid on a bench. Avoid these, as the lids can no longer hold pressure.)
Temperature shock
Glass jars are very vulnerable to temperature shock, particularly from uneven heating. Temperature shock can cause them to crack or shatter. Always put hot contents into hot jars. If sterilising by oven, put the jars into the oven before heating it. If sterilising by water, fill the jars and immerse them at the same time.
Heat
I'm going to assume you know how to work with hot things. This uses regular stovetop cooking temperatures.
Storage of full jars
Since heat and cooling is what seals the jars, exposing them to too much heat can also unseal them. Store in a cool, dry place.
Safe storage time depends on the contents. As a rule of thumb, anything with a high acid and/or sugar content will last years; anything else, try to eat it within a few months.
- Acidic bottled foods include pickles and pasta sauce.
- Sugary bottled foods include jams and jellies, and fruit if in a heavy syrup.
Sometimes the contents of a jar spoils, even if we've done all the right things. Watch out for the lids swelling, or a change in the colour of the contents. If I find a swollen lid, I smell the contents to check if it's still ok, put the jar in the fridge straight away and eat the contents soon. It may be easiest to re-cook the contents, e.g., bake fruit into muffins. If you choose to do this, always check by smelling, and remember, if in doubt, throw it out!
Process
Cook your food. I'm going to assume you know how to cook whatever you want to cook. Make sure that the food is in small enough pieces to go into your jars (diced, grated, or blended - the stick blender is handy because you can blend after cooking without having to transfer to another vessel). Keep the food hot for bottling.
While the food is cooking, take your clean jars and sterilise them. Don't forget to sterilise the lids too. Sterilise either in the oven or with boiling water.
For oven sterilisation, place the jars and lids separately on the oven racks. Put them into a cold oven, then switch the oven on. Set the oven to 120°C or 250°F. Once the oven has come to temperature, leave them in for ten minutes. Leave the oven on while you fill the jars, to keep the remaining jars hot.
I like to put each lid with its jar so I don't mix them up. And since my oven is on, I have some parsley dehydrating as well.
For water sterilisation, boil the kettle and fill the kitchen sink or a small tub with the hot water. Ensure you have enough water to cover each jar lying on its side. Put the jars in on their sides so that they fill with water at the same time as they are immersed, and turn them immediately so that all sides contact the hot water. This prevents temperature shock by ensuring that both inside and outside, the whole way around, all heat up together. Keep them in the hot water until ready to use.
(Note to those I've mentioned this to in person: It turns out I was wrong about having to ensure the jars are thoroughly dry before filling them. My mother said she just shook out the water and that was enough.)
When the food is cooked and the jars are sterilised, take the jars out one by one and fill them, keeping the other jars hot until you're ready. Using a funnel helps prevent spillage on the lip of the jar, but if there is any spillage, wipe it clean before putting the lid on. Fill the jars to just below the lip - remember that the level will go down slightly when cool (that's how it seals). Put the lid on tightly straight away, and set the full jar on a heatproof surface (e.g., the draining board of the sink) to cool.
If you end up with a partially-filled jar, use that one first, even if it seals. I generally don't store them with the rest, but put them straight in the fridge.
As the jars cool (possibly even while you're still filling the rest of them), you may hear the lids pop with the same sound opening a sealed jar makes. This is a good thing! If any of the jars have the "safety button" on them, it will go in just like when the jar came from the shop; any jars without it will also go in when sealed. If the centre of the lid looks concave (slightly hollow) and doesn't move when pressed, the jar has sealed and is safe to store.
Any jar that doesn't seal by the time it cools to room temperature must be put in the fridge and eaten soon. If you can press the lid and it goes in but comes out again when you release it, the jar is not sealed.
Labelling
Make sure you label the jars so you remember what's in them! The label should include:
- What the food is (e.g., pasta sauce, stewed apple)
- What date it was bottled (including year)
- The list of ingredients (although if these are only for your own household and you use the same recipe regularly, you can probably omit the list)
I write on masking tape for my to-keep jars, omitting the ingredient list and writing more complex recipes on a clipboard with the dates to catalogue by. For jars that I donate back to the food bank, I type and print large labels with complete ingredients lists, and stick them on with sticky tape. You can make them fancy with fonts and borders if you like, but you don't have to.
Ready to go to the shop! I've started putting a note on the label asking for the jars back - I hope I get some!
I hope this encourages you to try bottling something you like! And remember, wash and save your glass jars!