I had the ill thought of adding raw lemon to my apples jam (half for ~2.5lt, in other words half for blender load), it tastes inhumanly bitter. Apart from the level of acidity which can be fixed with soda I don't know how to fix the bitterness, the lemon peel nearly causes me nausea.
Is It fixable?
If not, how can I reuse it? Chutney?
What's the mininum number of ingredients for chutney?
Marmelades with a certain bitterness are popular in some areas, eg typical british orange marmelades.
The mistake you made was likely in using lemon peel with the pith still on and on top of it blending it all - Some marmelades use a bit of pith, but these recipes usually involve cutting the peel and pith coarsely then candying it as is.
Mixing your bitter jam with one or more batches of jam that is without any bitter element could balance it to a pleasant level, but there is no guarantee and you could spoil the other batches that way. One could test by making a fresh batch and mixing, say, one tenth of the bitter batch in, then gauging the result.
Making a chutney from it has potential for one specific reason: Chutneys can be made mildly to very salty, and salt is about the only thing that can mask/balance bitterness that is too strong for sugar to balance. Also, bitter goes well with spicy hot, and chutney goes well with spicy hot. Do mind that some of the spices common for chutneys add further bitterness, especially when there are imperfections like too stale hot spices or slightly over-toasted cumin in the mix ....
Acid can also balance bitterness a bit, but in your specific case it is unlikely to help, since your jam is probably already strongly acidic.
Do you eat marmalade? If so be inspired by that and cook further. This will give you the opportunity to adjust sugar levels as well as cooking out some of the bitterness. You may want to use a food processor if the chunks are too big.
Chutneys (of the keeping kind) are usually based on vinegar and some brown sugar, with plenty of onion. I often make an apple/onion chutney, but I don't think I've ever used lemon in one, though it should be possible from a pH point of view to preserve this way. Starting from where you are this could be hard to reach without adding a lot, as you were making a sugar-based preserve.
You don't say when you made this or how you have stored or plan to store it but a mix of cooked and raw ingredients in a preserve isn't a very good idea fom a spoilage and food safety point of view. I won't go into detail here without knowing that, and as it's been covered many times before, just note that you need to be careful.
