Step 1

Sterilise the jars you'll be using to store the marmalade.Choose glass jars with an airtight, metal lid and ensure they have been washed in the dishwasher or by hand in hot soapy water then rinsed well.Check that the metal lids do not have rubber inserts. (See Note 9)Preheat the oven to 130 Degrees C (270 F) and place the jars in the oven for 15-20 minutes.

Step 2

Place 2 saucers or small plates in the freezer, ready to check for the setting point of your marmalade.Thoroughly wash the grapefruit and lemon. Remove each end of the grapefruit to get rid of excess pith. Remove each end of the lemon. Cut the grapefruit and lemon into quarters length ways. Holding two of the quarters together, slice as thinly as possible and remove any seeds.

Step 3

Place the citrus slices in a non-reactive bowl. See Note Add the 6 cups of water, cover the bowl and leave the fruit to stand overnight, up to 24 hours. If your bowl is not large enough to accommodate all the water, add what you can and add the remainder the following day. It’s best to make a note of what you have added.The following day, place the fruit and water into a very large, non-reactive saucepan. – See Note 5.

Step 4

Over medium-high heat, bring the fruit and water to the boil. Rapidly boil for approximately 15 minutes or until the peel is tender, stirring occasionally with a long-handled wooden spoon – See Note 6.

Step 5

Add the sugar and stir well to dissolve it. After dissolving the sugar, return the fruit to the boil, stirring occasionally. Continue to stir until the marmalade reaches setting point - I start to check at about 10 minutes. When the very aggressive bubbles subside to a slower, gentler boil, that's an indication that your marmalade may have reached setting point – See Note 7.Remove from the heat to conduct the wrinkle test. If not set, continue to boil for another 1 minute and then test again.

Step 6

To test for setting point, I use the “wrinkle” test. Take one of your saucers from the freezer and pour a small amount of marmalade onto it. Let it cool for a minute then push against the marmalade with the tip of your finger. If the surface wrinkles slightly, it means setting point has been reached.Alternatively, if you are not confident checking this way or are not experienced at making marmalade, you can use the fail-safe method of using a jam/candy thermometer which you clip to the side of your saucepan. When attaching your thermometer, make sure that the base is not touching the bottom of the saucepan. Your marmalade has reached setting point when the temperature reaches 104.5 degree C or 220 degrees F. (Taking it much higher than this will result in the marmalade being overboiled, the pectin being destroyed, and therefore, your marmalade will not set.)At this time, your marmalade will look very liquidy - it can take 24-48 hours to completely cool and set.Please note, this recipe will produce marmalade which has a soft set; it will not be as firm as many commercial varieties which often contain additives.

Step 7

Take the mixture off the heat. If there is any scum on the marmalade, add a teaspoon of butter and stir; that should settle the scum.

Step 8

Let the marmalade stand for about 10 minutes to allow the fruit to settle. If you bottle it immediately, the fruit will not be evenly distributed but will settle at the top of the jar.

Step 9

Remove your jars from the oven and carefully ladle the marmalade into the heated, sterilised jars. The jars should be filled as full as possible to minimise the amount of air between the marmalade and the lid. The marmalade should not touch the lid. Seal tight once filled with marmalade. See Note 8You need to be very careful. Splashing yourself with hot marmalade will result in a very serious burn. I suggest you have clothing with long sleeves and ensure that you do not have children nearby.