Jam: intro

I found some old plums while sorting out my fridge yesterday.  After umming and ahing I made some plum and star anise jam which is lovely.  It set me thinking about a sort of 'template' recipe for jam.
Before I give that there's a few things to go over.

1.  Pectin.  Some fruits are low in pectin and some are higher.  Pectin is essential for setting.  If there's not enough pectin your jam won't set.  If I don't know, I google and here's a useful site for info.  Scroll down for a table of info but actually the whole page is informative, albeit not terribly attractive.
http://www.pickyourown.org/pectin.htm
My plums were very ripe so I added some lemon juice.  Works a treat!  You can buy jam sugar which has added pectin and that also works well but it is dearer than ordinary sugar.  You can also buy pectin but I never have so cannot comment, and according to the link above you can make pectin.  Something to go on the list, I suspect.

2.  Setting point.  This page says it all - I do the wrinkle test!   Works for me.
http://www.kilnerjar.co.uk/setting-points
You can also find youtube clips that explain and show.

3.  Jam jars.  Use ones you have recycled (keep the lids too) if possible.  I clean them either in the dishwasher or in very hot, soapy water.  I keep them warm in a cool oven on a baking tray of some kind.  How many?  No idea, it depends on how much fruit.  I make a guesstimate and add a couple more for luck.
If you don't have any you can buy them.  Hobby craft and Lakeland both sell jam jars although they are expensive.  I prefer to use the Jam Jar Shop for price and for variety.
http://jamjarshop.com/  

4.  Ditto with sugar.  How much depends on how much cooked fruit you have.  A pint of fruit equals a pound of sugar, more or less.

5.  Ditto with any extra flavours.  I know plums go well with star anise so I usually pop one into the first stage, cooking the fruit, removing it before jarring the jam.  Port or other alcohol needs to go in nearer the end of the whole process.  Read up about it - I always do and bless Google.

6.  If the above sounds very casual, it's because it is.  Housewives/keepers were making jam long before the scientific stuff was discovered.  I'm kind of gung-ho with it all now and rarely have a failure.  The worst that can happen is that the stuff hasn't set and you can add more lemon juice and reboil until it does.  The flavour will change with longer cooking but not in a bad way.
The most important thing is to be very clean, sterilise your jars, wash your fruit and don't use any fruit that has actually gone 'off'.

The template recipe is in the next post.