Rules of jelly thumb?

[bunn]

Yesterday we had lamb chops, and lacking anything interesting to dress them with, I made a lemon and mint jelly.

I took two lemons, zested and squeezed them, added some water and some sugar and boiled for a bit. Then I tasted and it seemed a bit tart so I put some more sugar in. Finally I added piles of chopped mint and boiled a bit more.  At that point it set if I dripped it onto a cold plate, so I strained out the mint and zest and stuck it in the fridge to congeal.  It was good.

Thing is though, I have no idea if I could have made a larger quantity of less acidic jelly if I'd put more water in, or if it would then just have been a syrup.  Or if I could have got away with one lemon.  I have a vague feeling that this has something to do with the pectin content of the lemons, but how one estimates that, I do not know.

Does anyone know about the theory behind jam and jelly recipes?   I'm OK with making stuff from a recipe, or even improvising based on a recipe -  but would like to know more about how the gelling bit works so I can be more freeform about my jellies in future!  Google is not being helpful today: it gives me recipes, not an understanding of the principles behind them.

Comments

[bunn.livejournal.com]

oooh, thanks for the recommendation (and the offer of spare book!) Copies do seem to be available here second hand, so I shall snag one of those and save you posting it.

I should probably check my local independent bookshop before buying online, we are lucky to have a couple of quite good ones (one mostly new books, one second hand).