The pith of grapefruit is quite bitter. You can cut away about half of teh thickness of the white part and use the yellow part in the marmalade. A blend of different citrus can also be done. Citrus, with regular pectins can take a month r longer to set. Using Pomona pectin, the results are much faster. Pomona is a citrus based pectin, so it may even set with very little added calcium. As mentioned in other recent threads, regarding Pomona, I use a blender to dissolve the Pomona powder in some of the liquid, or water. Then, its poured into the boiling mixture and will quickly dissolve. Lastly, the calcium water is added.

I love tomato jam, and have several versions of it. Here are three - the passionfruit one is particularly yummy. Tomato Jam 2 1/2 kg red or yellow egg-shaped tomatoes 2 1/2 kg white sugar 3 lemons Cover tomatoes with sugar and leave overnight. Next morning, strain off liquid, bring to the boil and skim. Add the tomatoes and boil slowly for 30 minutes. Remove the tomatoes, and continue boiling the syrup till it is thick, then add the juice of the lemons. (If desired, the lemons can be sliced and boiled with the tomatoes.) Spoon tomatoes into jars, pour syrup over till brimming full, and seal immediately. If desired, the pulp of several passionfruit can be added to the mixture. (I just use the lemon juice.) Passionfruit and Tomato Jam 500g cooking apples, peeled and chopped pulp of 9 passionfruit 1kg ripe tomatoes, peeled and sliced 1.4kg sugar Cook the tomatoes and apples gently in a saucepan until soft. Add warmed sugar, stir until dissolved. Boil rapidly for 30 minutes, then add passionfruit and boil until it gels when tested. Pour into warm jars and seal. Green Tomato Jam 2 Golden Delicious apples 1.2kg green tomatoes 900g sugar Core and thinly slice the apples, cut tomatoes into slices. In a heavy saucepan combine apples and tomatoes. Stir frequently, cooking over low heat for about 30 minutes or until tomatoes have disintegrated and most of the liquid has evaporated. Add sugar and cook until syrup is thick (about 20 minutes more). Pour while hot into sterilised jars.

Once it is cool it will be as solid as it gets. Tipping it will not harm it and it will keep as long as it is well sealed. Processing them or reprocessing them will not make it set any better. The failure to set is often because the sugar wasn't measured right, or you had too much fruit for the sugar. In other words the ratio of sugar to fruit was not right, to make it set completely. When making jams and jellies measurements must be exact.

Thanks Dave and Annie. As you can tell, I'm winging it here :) I'm kinda doing a spinoff of the Ball Orange Marmalade recipe (without the pith/rind), but I'm not sure what type/how much pectin to use. I hope it doesn't come out bitter; I didn't realize that's why citrus freezer jams were more popular, thanks for the tip. Maybe I'll swap out the two lemons for a couple of more clementines, then just add a splash of lemon juice instead. Annie, "don't fear the Reaper!" Hahaha. I use them in my "go to" strawberry pepper jam recipe: Strawberry Pepper Jam •2lbs fresh strawberries •4-5 cups granulated sugar •1 superhot pepper- finely minced (Annie, try 1/2 a Reaper) •1-2 TBSP lemon juice •4 TBSP powdered pectin (Yields roughly seven 1/2 pints) ^This recipe is ALWAYS a hit! Especially around the holidays- even my Grandmother (who's 85!) BEGS me for this stuff! (For a Chocolate version, mix 1/4 cup of cocoa powder into the sugar before adding to the pot. Mmmmmm....) This can go on anything from crackers with cream cheese to vanilla ice cream! I'm going into jam making mode this week, and thought I'd try making a new flavor (Orange). Thanks everyone! Edited to add: pectin suggestions for the Orange Jam? i.e.- powdered vs. liquid?