non thickening orange marmalade

I'm not going to pretend to be an expert, but I've been succesful at it. From the notes above, the pith, peel and seeds are super important. I'm wondering about what ratio of water to fruit and sugar to fruit was used? Also I'm assuming you cooked the juice, water and peel/seeds thoroughly before adding the sugar? Again I don't know if what I do is common practice but it certainly worked to cook the juice/peel/seeds (in their cheesecloth bag) for a really long time - 12 hours or more - at not quite a simmer and until it reduces by a half.

Speaking of marmalade, the best ever, easiest (at least as far as the cooking part) marmalade I've ever made is this one: http://food52.com/recipes/16984-valencia-orange-marmalade You go through some preliminary steps to extract as much pectin as possible from the lemons. It gels up beautifully, without your fretting over a thermometer. (People have been making marmalade for centuries without thermometers. The visual cues offered by Ms. Saunders are much more helpful -- and foolproof.) For future reference . . . . ;o)

Hmmm... 202 is usually considered the standard gelling point (where either the frozen plate or spoon "sheeting" tests need to be applied). Citrus marmalades can take awhile (sometimes hours of cooking) before they set properly. So, if it was really an hour at 210, I'd go for 220 and keep cooking/testing -- and it may be another hour. Assuming you used the whole fruit, there should be plenty of pectin -- note that the highest concentration of pectin is in the pith, so if you removed the pith to reduce the overall bitterness, it will take longer to set.

I find that the pectin content in some oranges is very slight. I sometimes add a bit of Pomona pectin. Lemons always work.

Whoops, I was holding out for 220.

Good advice from Stephanie. I was holding out for 212 on some marmalade this week, and it ended up too thick.

Keep boiling. The temperature will hold at 212F while the water boils off and then the temperature will start to rise and you'll notice the marmalade getting thicker as the sugar cools. It's always a good idea test a small amount by letting it cool on a plate to see how thick it will be once you finish.