Wednesday 25 August 2010

Making Jam

Since we have fruit trees, I make jam during the summer reasonably regularly. Sometimes Simon does too, and although we hadn't done much jam making before we came to live here, we really haven't had the sort of problems other people seem to have, particularly with jam not setting.

Now that I have played around with various methods and settled on a basic technique that works for me, I want to work on improving the fruity flavour and reducing the sweetness of our jams, so I've been reading up on jam making.

Yellow plum jam on the boil.
An easy rule of thumb is that jam should be 50% sugar and 50% fruit. That's the ratio I currently use, but I'd like to drop it to 3 parts sugar to 4 parts fruit. By law in France, commercial jam producers must adhere quite closely to the 50/50 rule, or they cannot call their product confiture. But they (and their consumers) are clearly interested in variations in the fruit/sugar levels - for taste, for health, to save money, and who knows what else. You can buy jam in the supermarket with a 65% fruit content, so it becomes 'confipote' or 'fruité intense' or 'confiture allégée en sucre'.

Why is a low sugar jam not a jam then? It's mainly because the sugar acts as a preservative, binding the water content and preventing moulds from developing then causing the jam to ferment, which alters its flavour and texture (it becomes more liquid). When heated together the sugar attracts the water from the fruit. The cell walls in the fruit burst and release pectin too. The pectin is only released at high temperature, and the presence of the sugar means that boiling point is above 100°C. (Beware - the pectin will irreversibly break down if you go more than a few degrees over jam temperature for more than a few minutes.) Dispersed amongst the fruit water, the pectin molecules cannot join together, but once the sugar has bound the water, the pectin can form a gel. A certain amount of evaporation takes place as well, which helps thicken the mix. The ideal ratio for this transfer of molecules to take place turns out to be a sugar content of between 50 and 65% (remember that the fruit itself contains sugar). Apparently too much sugar can cause crystalization. The final player in the mix is acidity, which aids the attraction of the pectin molecules to one another. Once the jam cools, all the elements should have formed a network resulting in perfectly set jam.

Yellow plum jam and apple and blackberry jelly bottled and cooling.
Many people will tell you that a runny jam cannot be reheated and boiled a bit more to thicken it, others will tell you the opposite. I'm in the second camp - my experience is that if it doesn't set overnight in the jars, chuck it all back in the pot and boil it hard for 5 or 10 minutes and re-bottle it. If your problem was it hadn't reached jam temperature the first time it will be fine. If your problem is that you have boiled it too hard in the first place, try adding some pectin and strictly controlling the temperature at jam temperature this time round.

Many people will tell you to add lemon juice or half a lemon to any and all jams. This is presumably on the understanding that the pectin needs that hit of acid to reassemble and that the lemon itself contains pectin. My personal preference is for no lemon - I find the flavour overpowers the fruit, and I can't see why the acid naturally present in your fruit of choice wouldn't be sufficient to activate the pectin.

Many people will tell you to make sure you mix fruit that is rich in pectin (citrus, apples, redcurrants) with fruit that has less (apricots, peaches, strawberries, cherries, blackberries), but we never have any problem with our cherries, so I am not convinced this is necessary. However, I have this year made a batch of apple pectin and put it in the freezer for adding to jams next year. This so I can reduce the sugar a bit but still get a good set without cooking the jam for too long and losing flavour.

Apple pectin is easy to make. I use my imperfect apples, cut out the bad bits, chuck them in a big boiler, cover with water and boil for 20 minutes. The apples are well and truly mushed by then. I tip the lot into a muslin which we suspend from the back of a chair over a bowl. The theory is that the resulting already slightly gelled liquid is pectin. I rinse out my muslin in very hot water and hang it on the line to dry, but if you were worried about it not being sterile, you could simply iron it before using.

Many people recommend using copper pans for jam making as the metal ions link to the pectin and aid gelling. However, the tarnish on copper pans is toxic, so I don't fancy it, and, like beating egg whites in a copper bowl, I've never found it necessary. If you do use a copper pan, apparently calcium citrate, available at the pharmacy, neutralises the vert-de-gris.

Many people swear they can tell when their jam is ready by putting a teaspoon of hot jam on a cold plate, waiting a few minutes then pushing the jam. If it wrinkles it's ready. This technique never worked for me, although Simon uses it. I always use a thermometer and make sure the jam has reached 105°C and stays there for 5 minutes.

Pectin is released rather slowly, so a relatively long cooking period is required, but this means that many volatile aromatic flavours are lost. There is no reason you can't cook the fruit first to release the pectin, then add the sugar and leave it to dissolve and bind up the water. This is useful when making jellies, as you can boil the fruit, strain through the muslin overnight, then add the sugar and bring slowly to the boil to ensure it is all dissolved, then boil hard to reach jamming temperature. Making apple pectin should also solve this problem, in that you are adding it already activated to another fruit jam. It doesn't matter that the pectin has lost its apple flavour by being cooked hard earlier.

To help prevent loss of aromatics, don't stir the jam too much either. Having said that, though, it is wise to stir every now and then, just to check it's not burning on the bottom.

The foam that forms on top of the boiling jam must be removed because it leaves aerated trails through the jam which can allow moulds to grow. However, there is no reason you can't eat it, and added to yoghurt, or spread on bread still warm as an after jam-making snack, it is delicious.

To sum up, you have two approaches to choose from when jam making:

Rapid - the current trend. Chop your fruit and macerate in an equal quantity of sugar first and the fruit will break down quickly and release its water and pectin.

Long - unavoidable if you want to reduce your sugar content or increase your fruit content. The advantages are that water will evaporate and you will get a thicker syrup form, the fruits burst, the pectin is liberated, the house smells fantastic...but you risk losing flavour with the aromas.



Blue Witch said...

Thank you, that explanation was fascinating to someone who's made jam for years and years and never really known exactly why it works, except that it does!

One tip given to me years ago when I started using metal lids and not cellophane, that you may already know, is: tip the jam over and back three times as soon as you screw the top on (I cover top with a tea-towel in case of hot seepages) which effectively sterilises the air left in the jar, which prevents any possible mould problem, and also stops shrinkage if the jam is a few years old before you get round to eating it.

Pollygarter said...

What do you think of the French habit of putting spices in jam? I like to let the fruit speak for itself, personally. The recipe for 'English Marmalade' in my Confitures book has vanilla in it...

Keir said...

Susan, since moving to France this summer, I too have started up the jam making due to an excess of fruit in the garden. I found that with my small red plums and with the Reine Claudes I could use a ratio of about 1 cup of sugar to 1 kilo of fruit. This came from one of my Italian cookbooks and it turns out sweet/tart enough for my taste. I didn't add any pectin/sugar with pectin in it, and used the longer cooking method.

Susan said...

BW: aha! so that is what turning your jam jars upside down after filling does! You see a lot of advice to turn the filled jars upside down to cool. I thought it was a technique for ensuring your fruit didn't float to the top. Why your fruit wouldn't just float to the bottom instead if it was going to float and why it didn't leave the lids covered in jam in an annoying way I've never understood.

Polly: Simon would have a major sulk on if I put spice in any of the jam. Vanilla goes with many fruit fantastically well, but with citrus? Ginger yes, vanilla no. I have had some very nice spiced apple jelly though. In general though I prefer no spices in jam.

Keir: I'd be seriously concerned about fermentation with that low a sugar level. How long are you storing your jam and where?

Andrew Waddington said...

From my experience jam is very hard to make, I didn't realise the French were so strict on ingredient mixing

Frankofile said...

I've learned a lot of useful tips for a novice jam-maker, thank you! The cherries and apricots have wowed me this year, and visitors have enjoyed making greengage jam to take home. My young fruit bushes didn't produce enough for the intended blackcurrant jam - why do I only find blackcurrant jelly here in France?

I started off using a packet sugar with pectin that claimed you could use half the usual amount of sugar; when that disappeared from the shelves, I moved to packet sugar&pectin mix. Both perhaps reduced the boiling time. Anyway the flavours are lovely and I doubt any will need to keep for a year!

BTW love your blog.

Susan said...

Andrew: I'm sure that the French regulations for commercial jam are not very different for any other western country.

I don't generally have any difficulty making jam, but it doesn't matter if your jam is runny - just use it as icecream topping.

Frankofile: I can buy Bonne Maman Blackcurrant jam (with whole fruit, not just jelly) in my local supermarket.

I used the special sugar with added pectin a couple of times this year and thought it was a rip off. It didn't explain you have to get the jam to jam temperature, it just says 'boil', and it is more than twice the price of ordinary sugar. I am sure it is cheaper and more satisfying for me to make my own pectin.

Glad you like the blog :-)

Jenny said...

Wow...thank you for the wisdom.

Unknown said...

This was really an excellent, thoughtful write-up. I love fruity jam with a lower sugar content, though, and suddenly find myself a bit nervous about all the jam I have making this summer, with slightly to more than slightly reduced amounts of sugar. Hmm. Maybe I should begin giving them away now! They really do taste so good, though...

Susan said...

Tammy: Keep them cool and see what happens, I guess :-) Love your blog, btw.

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