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How to Pasteurise a Surfeit of Berries
Nature can be generous, sometimes too generous! As I rarely use sugar, I’ve found that pasteurisation is a great preservation technique, as an alternative to cordial, and it’s very simple.
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How do you make sure you have a year round supply of your favourite herbal power shots and wild juices?
One way is to make cordials, jams and jellies but I use less and less sugar these days. Alcohol and vinegar make good preservatives. But sometimes you just want them plain, or want to decide later what you’ll turn them into. Freezing is an option but I quickly run out of space.
Pasteurising is the best way to ensure you can keep juices, herbal and mushroom decoctions without buying a second fridge, although they must be refrigerated once opened. If like me you love the sight of larder shelves groaning with bottles and jars, labeled with mysterious handwritten labels, then pasteurising your own juices is definitely for you!
Pasteurised fruit and herb juices - including precious herb or mushroom decoctions - can be made by heating the extracted, filtered juice and then hot-filling it into sterilised bottles. This method works perfectly well and is a lot easier to do in a domestic kitchen than heating or baking the already filled bottles!
Ironically, I have found that elderberry juice pasteurises itself when the juice is extracted by boiling to make elderberry syrup. This makes a really rich juice that is excellent for cooking.
How To Pasteurise Fresh Seasonal Juice
Heat the juice in a stainless steel pan* to 80-95 degrees C for 1 to 15 minutes. The exact time can vary according to the fruit. I prefer using a lower heat as I think as this preserves more of the beneficial properties of the juices. The length of time depends on the size of bottle that you are then going to fill. As a rule of thumb – and this has worked for all the wild juices I have tried – allow:
15 minutes at 80 degrees celsius (176 for you Americans) for every 500 ml of juice or herbal infusion.
Check your temperature with a cooking thermometer and make sure you sterilise and pre-heat your bottles in the oven - or winemakers sterilising fluid - and sterilise the screw caps. It’s that simple!
If you do decide to go into small scale production, drill a hole in a stainless steel bucket and attach a tap (or two) to make a very effective bottle filler that can be sterilised.
I also find that for quantities over a litre that I can hold the heat better for longer in a slow cooker as I can then get bored and wander off without ending up with evaporated juice and a burnt pan some hours later!
Alternatively you can pasteurise in the bottle, the more traditional way.
* A stainless steel saucepan is best as the fruit acidity reacts with aluminium. Although leaf juices are not so fussy it is best to avoid using aluminium as there is early evidence that aluminium contamination can be linked to Alzheimer’s disease and some cancers.
Traditional Pasteurisation Method
Put the juice into the bottles before sterilising and put the caps on, leaving them slightly loose.
Put the bottles into a tall stock pan standing upright on a mesh insert so they don’t touch the bottom. Fill the pan with water, up to the neck of the bottle, and bring up to heat. Now hold the heat at the right temperature for the prerequisite amount of minutes:
10 minutes at 80 degrees when filling 0.33 cl bottles (330 ml)
15 minutes at 80 degrees when filling 0.50 cl bottles (500 ml)
20 minutes at 80 degrees when filling 0.75 cl bottles (750 ml)
Then remove from the heat. Using heat gloves remove the bottles and tighten the lids. Allow them to cool.
Your pasteurised bottles of juice will keep at least a year in a cool dark place. Refrigerate once you have opened them.
So if you’ve been picking plenty of berries this year do remember pasteurising as an option. Happy picking and try not to eat them all before you get them home!
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