Wednesday, 11 January 2012

Sterilising Bottles or Jars by Heat Processing or the Campden Process

Most of us are fairly familiar with sterilising jam jars or kilner type jars in either Milton Solution, baby sterilising tablets, boiling water, via the dishwasher, but not so many people are familiar with using a heat process or the Campden Process to preserve food in bottles or jars for longer term keeping.  It is not a complicated process, you have to be patient but it does result in a longer shelf life for home preserved foods.

Heat Process

The heat process which is my preferred method is to place your chosen bottles (which have previously been sterilised by one of the methods mentioned above) and then the contents added to the jars or bottles.  I feel that you cannot be too clean when you are dealing with food for long term storage.  The bottles or jars are then placed on a trivet or false bottom in a deep saucepan. I have used a soft tea towel or towel to pad the jars or bottles against the direct heat and thus putting the jars at risk of breaking and leaching their contents all over the pan.  Loosely fit screw tops or secure corks with string or fine wire.  Fill your chosen pan with cold water to the same level that your syrup comes to in the bottle or jars (allowing for the headspace).  Bring the water to simmering point 88 degrees C/190 degrees F and hold for 30 minutes.  Remove the bottles and secure the tops.  When cold if using corks you can seal the corks by dipping in melted paraffin wax. I do use the bottles with the metal pressure closure on as sold by Lakeland etc  (the sort that are used commercially for the French fizzy lemonade for this process as well. This method works by excluding any air from the bottles which can make the food go off, removing any air by heat forms a vaccum seal which protects the bottles contents.

I use a baby steriliser for the process of bottling syrups as it is an ideal size for processing syrups and cordials at home.  Just using the timings above and I have been very pleased with the results so far.   Check out my previous post here for further explanation

For bottled fruit I use a preserving pan or deep heavy based saucepan following the manufacters instructions - I am particularly thinking of Kilner jars here.   I tend to submerge the jars fully in the pan and as the jars heat up you will see bubbles rising from the jars into the pan.  Once processed I leave to completely cool in the pan.  The next day I check to make sure that the bottles have sealed corectly and there are no leaks.  If there are leaks put the bottles back into the pan and re-process.  If the seal does not take at all use up that jar or jars as quickly as possible as they will not keep. 

The Americans also when they make jam, heat process the jam jars  (after the jam has cooled in the jars) and their contents in this way for the same reason.  You can do this with home made sauces, bottled fruit etc.  to give them a longer shelf life.  However different fruits have different processing times and therefore care must be taken to follow the timings given for that fruit and particular method of

The Campden Process

As I understand it Campden tablets are used in wine making for stopping a wine from working or for sterilising demijohns etc.  They contain sulphur so I am not too keen on using this method as it can bleach the fruit and leave it with a slight sulphur flavour..

Simply crush 1 Campden tablet and dissolve it in 1 x 15ml/1 teaspoon warm water and then stir into 600ml/1 pint of syrup or juice before pouring into the bottle.  Seal well.  The juice will supposedly keep for up to six months using this method.

I would not use this method for fruit bottling at all.

I hope that this will assist you in making sure your home made goodies have a longer shelf life.

Take care and enjoy the experimenting



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