IT MAY SEEM strange, but I always associate jam making with the winter months. This is because we tend to freeze our fruit as it is picked and then make jam in fairly small batches as we need it.
There's something very pleasant about having the kitchen filled with the scent of strawberries or raspberries in the depths of November, a lovely sense of summer (or what passes for it in Ireland) as the winter rain lashes against the window panes. But there is something special about using fruit that has just been picked, too.
There are several reasons behind our winter jam work. The summer is busy enough as it is without doing all that boiling and sterilising of jars. But, also, there's the question of how some fruits and some jams behave.
Strawberry jam has a tendency to lose colour, so it makes sense to use it within a couple of months of making.
The strawberry, of course, makes one of the most desirable jams, simply the best with croissants and almost unrivalled in a queen of puddings. But the strawberry is dreaded for one major reason: a tendency to be a bit deficient in pectin, the substance that aids setting. For many people, strawberry jam ends up being unacceptably runny.
Now, you can either accept that this is the way that strawberry jam is meant to be (but, even so, some versions will be so liquid that it has to be drunk rather than eaten). Or you can take certain cunning steps to boost the pectin levels.
Commercial jam makers work in something like laboratory conditions, measuring levels of enzymes and natural sugars and what have you, and adjusting accordingly. In the domestic kitchen we just have to accept that every batch of jam is going to be different. Boosting the pectin level when you are using strawberries or apricots, for example, can have unexpected results. It is possible to end up with a jam that is so unrunny, to coin a phrase, that it has the consistency of a fruit gum.
Now, I realise some people like a stiff jam, but there are limits.
If you want a well-behaved jam, one that is liquid enough for pleasure but which manages to stay on the spoon while you transfer it from the jar to the toast, stick with raspberries. Raspberries are more tart than strawberries and tartness always seems to go with good setting.
Harold McGee, in his encylopaedic On Food and Cooking says that jam works because "like salt, sugar makes the fruit inhospitable to microbes". Jam, he says, is all about "the nature of pectin, one of the components of the plant cell wall, and its fortuitous interaction with the fruit's acids and the cook's added sugar."
If you need to boost pectin levels in strawberry jam (and if you like it stiff this is essential) peel the yellow skin very thinly off a lemon, leaving as much of the white pith as possible. Then slice up the lemon and put it in with the fruit as it cooks.
JOHANN'S STRAWBERRY JAM
1.6kg strawberries, cleaned
Juice of half a lemon
1.4kg sugar
Put the strawberries and the lemon juice into a large pot on a low heat.
When the juice starts to run, turn up the heat, bring to a simmer and cook the berries until soft. This will take about 20-30 minutes.
When soft, turn down the heat and add the sugar. Stir until the sugar has dissolved. Turn up the heat and bring to the boil, then boil fast.
Test for setting after 10-15 minutes by putting a teaspoonful on to a cold saucer in the fridge and leaving it for three minutes. Push the cold jam from the edge with your finger. If it wrinkles, the jam will set, otherwise boil for another five minutes and try again.
When the jam reaches its setting point, remove from the heat and leave to cool for 10-15 minutes. Pour the jam into hot sterilised jars (spotlessly clean and put in the oven at 240ºC/gas mark 1 for 20 minutes) and cover with lids or waxed paper and cellophane.
Makes about seven jars. If you want it stiff, add peeled lemon slices as mentioned above and remove them at the end.
From Grow and Cook by Tom and Johann Doorley (Gill & Macmillan)