So how do you prevent all your hard work from being wasted?
Firstly, it is important to never stray far from your preserving pan; althouth it is tempting when it takes 40 minutes to cook blackcurrants or 2-3 hours to reduce a chutney. Your attempts to not waste time and get on with something else could result in the whole process being a waste of time if it burns. For this reason, be sure to have everything to hand before you start - e.g. don't go rummaging elsewhere for your jam jars after you have started the cooking process. Be on hand to give your jam/chutney a stir every now and then. I have a fantastic preserving spoon - a long handled wooden spoon with a squared off spoon-end (from Lakeland) that is just perfect for scrapping the bottom of the pan to make sure everything is still moving around.
The key point for stirring a jam is after the sugar has gone in. Stir and stir and stir until all the grittiness has gone and then a bit longer to be sure because any undissolved sugar will catch and burn. I remember reading in several preserves books that once you get jam onto a rolling boil to reach the setting point you must not stir it as this will lose the boil. Good grief, they make it sound as if doing so will somehow destroy the jam setting spell and all will be lost. I have discovered from experience that stirring during a rolling boil is essential when making plum jam. It is true that the boil drops for a moment but it soon returns when you stop stirring and it is better than having plums sticking to the bottom of the pan and burning. I would add a note of caution: sticking a spoon into a vigorously boiling pot of jam turns it into an angry volcano that spits and spats at you. Speaking as an ex-science teacher, I would not let a pupil of mine do such a dangerous thing and would certainly recommend the wearing of goggles if they did! So, hold your long spoon at its maximum length and stand well back, wearing glasses if you have them. Alternatively, temporarily remove the pan from the heat, give it a thorough stir then return it to the boil.
Chutney becomes more prone to sticking the thicker it becomes so be prepared to dedicate more of your attention towards the end of the chutney making process.
If you have ever burnt your jam or chutney then you'll remember the smell well and will be super sensitive to it in the future. This is a good thing as it will give you the chance to save the preserve before it is ruins beyond saving. Be aware that a similar smell occurs when small amounts drip or splatter onto a hot hob so it may not be your preserve that is burning after all. If you suspect burning then remove the pan from the heat and give it a tentative stir. If you feel a layer at the bottom that is stuck then stop stirring. If you are to save your preserve then it is not a good idea to stir the burnt layer into the non-burnt stuff above. It may be that your jam is set or your chutney is thick and you can carefully bottle the non-burnt preserve without disturbing the burnt later at the bottom. I would strongly advise tasting it though to check that the burnt flavour has not penetrated it. Should your jam or chutney not be ready for bottling then tip it into another pan or bowl, clean out the preserving pan then return it to the preserving pan and continue as normal, again checking that the burnt layer hasn't affected its flavour.
So how do you remove a burnt on layer on the bottom of your pan? Firstly, a soak in very hot soapy water is a good idea. Try to remove anything that will come away easily so that only the really tough stuff is left. Next, use a blade hob scrapper if you have one or a wire wool pan scrubber. You can also use a sprinkling of bicarbonate of soda and boiling water to shift it.
Inevitably, however you clean your pan it will leave it scratched. This happened to my preserving pan and eventually I found that everything I cooked in it was sticking to the bottom. Somehow the scratches in the bottom of the pan make it more likely for things to stick in the future. I was finding it very labour intense to have to stir everything pretty much all the time, including things like blackcurrants that never normally stick. I feared it might be time to buy a new preserving pan but first I thought I would try polishing the bottom of it smooth again.
I started with a scourer and a thin layer of vegetable oil. This immediately came away black so I knew I was removing the top surface of the steel (a good thing in this case). Having rinsed that away with soapy water, I fitted a mini drill with a buffer pad and smear the bottom of the pan with toothpaste. Then I picked up the phone and had a nice long chat with my mum whilst polishing the pan with the drill in the other hand. Finally I gave the pan a thorough clean to remove the toothpaste and hey-presto it was smooth and shiny again!
For the final test I cooked up a batch of rhubarb (another sticker) and ginger jam and it cooked perfectly with no more than the normal level of stirring required.
I don't think I have ever met a preserve maker who hasn't burnt something at some point so if you do burn something you'll be in good company. It is disappointing and it is tempting to try to save what you can. As I have said, most of the time something can be salvaged but always check the flavour. Don't let it put you off, just chalk it up to experience and learn from your mistakes for next time.