This gorgeous homemade grapefruit marmalade recipe is made with pink grapefruit, using the whole fruit method so nothing is wasted! This recipe works with oranges and lemons too.
Bring a large, covered pot of water to boil with the whole citrus fruit. This Cuisinart pot from Amazon is a decent size for the job. Boil the fruit until they are very tender and soft. Grapefruit take about 2.5 hours. Drain the fruit and let them cool slightly before proceeding.
Place a cutting board inside a rimmed baking sheet (these Nordic Ware sheet pans from Amazon are great). This is to catch all the citrus juices! Slice each fruit in half to expose the seeds. Remove the seeds if there are any, then quarter each half. Seperate the flesh from the peel so that you can slice the peel thinly and chop the flesh, removing any membranes if they are tough. Transfer the sliced peel, flesh, and juices into a large pot (like this Cuisinart pot from Amazon).
To the large pot of chopped fruit, add the sugar and the lemon juice. Clip on your thermometer (like this fast-reading digital thermometer from Thermoworks). Bring the mixture to a boil on medium–high, stirring with a wooden spoon or heatproof spatula (grab this spatula from Amazon). When the mixture is boiling, this is when you want to start monitoring the temperature. Boil the mixture, stirring constantly, until it reaches 220°F (104–105 ºC). When the marmalade reaches this temperature, slide the pan off the heat, and let it cool for 2 minutes, then add the vanilla bean paste and give the marmalade a good stir. This is to ensure that your canned marmalade will have an even dispersion of peel/fruit and vanilla bean seeds.
Divide the mixture between 5 or 6 sterilized jars (I prefer wide-mouth mason jars like these Ball jars on Amazon), leaving a headspace of ¼ inch. If the 6th jar has a larger headspace, you are just going to have to eat it. Just kidding. Well, except that you can’t seal it to store at room temperature, so that will be your jar to enjoy right away, storing it in the fridge. Wipe the rims of all the jars with a lightly moistened paper towel. Top each of the jars with a sterilized lid, and tighten the band until it is finger tight. The Ball canning kit on Amazon is key for this step and the next! Get it on Amazon.
Line a rimmed baking sheet with a large kitchen towel (these Nordic Ware sheet pans from Amazon are great). This will be the “cooling station” for the processed jars.
To seal the jars, place them in a large pot, with a towel at the bottom to prevent them from rattling and cracking. Fill the pot with hot water so that the jars are completely immersed. Bring the pot of water to a boil with the lid on and once the boiling point has been reached, boil the jars for 5 minutes.
Take the pan off the heat, and let the jars stand in the pan for another 5 minutes. Finally, carefully remove the jars from the water bath and place them on the towel-lined baking sheet. You will hear a popping sound soon after, a good sign that the vacuum seal is proper. Let the jars cool, untouched, for 24 hours before putting them away.
Carefully remove the jars from the water bath and place them on the towel-lined baking sheet. You will hear a popping sound soon after, a good sign that the vacuum seal is proper. Let the jars cool, undisturbed, for 24 hours before putting them away.
Notes
This recipe makes roughly 5.5 jars of grapefruit marmalade, so make sure you prepare 6 jars and lids.