Due to several requests on the Cider Workshop group, here is Andrew Lea's advice on pasteurising apple juice:
What you need
- Glass bottles with good caps. Crown cap bottles are very good or alternatively you can use the screw thread bottles with 28 mm plastic caps which have been discussed here before. You can re-use the bottles many times but you need new caps each time, since you need to make a perfect seal.
- A big tall saucepan ('water bath') which the bottles can sit in and which you can fill with water to come most of the way (at least two-thirds) up the outside of the bottles. A false bottom or trivet (or even a folded tea cloth) is useful underneath the bottles to stop them bumping. The water bath needs to be able to sit safely on a stove top or burner. (You can also buy specialist electric pasteurisers which hold a dozen or so bottles).
- A digital kitchen thermometer with a probe to reach into the bottles.
- A good pair of thick rubber gloves, ideally with roughened palms.
- Some powdered ascorbic acid (vitamin C). This stops the juice browning and helps to preserve flavour and the opalescent cloud. It also won't do you any harm!
Fruit should be clean and well washed and free from any dirt, mould or decay. It can be small or misshapen, maybe slightly scabby or cracked, but it must in all respects be fit for eating. Making juice is not a way of using up inedible fruit.
Press out your apple juice. Strain it coarsely if you want, and add 500 parts per million of ascorbic acid. That is 500 milligrams per litre or 5 grams per 10 litres (i.e. one level teaspoon per 2 gallons, old money). The maximum amount isn't critical - you can easily add double with no adverse effect. Don't add much less, though, or it will actually make the juice browner (no kidding)!! Stir well to dissolve, and then process as soon as you can (because the juice enzymes are quietly destroying all that added ascorbic acid while you wait!)
Fill the bottles (uncapped) with the treated juice, to within about two inches of the top. Place them in the water bath on a stove top (you may find a camping stove or burner is more convenient than the kitchen cooker) and pop the thermometer into one of the bottles. Heat rapidly to bring the temperature of the bottle *contents* (not just the water bath) up to 75 degrees C, bring them out of the bath with the rubber gloves and then cap them tightly and promptly before they cool. Lie the bottles on their sides while cooling, so the hot juice can sterilise the inside of the cap and the bottle neck. This also creates a partial vacuum during cooling which should draw the cap ever tighter onto the seal (like Kilner bottling). All the yeasts inside the bottle are killed by the heat, and if the seal is good then no more can get in. If you are familiar with Kilner jars etc you can of course use them instead.
The beauty of this method is that you do all the work up front and merely have to open a bottle whenever you need it over the next year or two. The alternative is to freeze the juice but it tends to sediment and you need to plan ahead to drink it - also you need a good bit of freezer space. This pasteurisation technique with the added Vitamin C makes juices like the ones you can buy in top-end shops for anything up to £4 a bottle.