Mary’s Microwave Grapefruit Marmalade

I’ve fine tuned this Grapefruit Marmalade recipe and use it periodically to top up supplies of the super zingy stuff. It’s very popular with certain family members.

Here’s my version:


3 medium-sized grapefruit, pink or yellow
1lb white sugar – you will need the same weight as the peeled weight of the grapefruits


Kitchen scissors
Large microwave-proof bowl – 3 litres or bigger
Bowls / plates to put grapefruit on as you work through the recipe
Saucer / plate
Food processor, or chopping board and knife
Serving spoon / desert spoon – to stir the marmalade while it’s in the microwave and to spoon it into the jars. Check the spoon will go inside the jar, to minimise spillage!
3 jam jars – 300g / 350g ones, clean
Tea towel – to hold the jars while you’re filling them up
Damp kitchen cloth / sponge – to wipe the jars at the end


  1. Put the saucer / plate into the fridge to cool.
  2. Peel the zest from the grapefruits.
  3. Snip the zest into thin strips (using the scissors).
  4. Remove white pith from the grapefruits.
  5. Weigh the three peeled grapefruits. Weigh out the same amount of white sugar.
  6. Chop the grapefruits – I do this in a food processor, 1 grapefruit at a time – removing any seeds as you go.
  7. Put chopped grapefruit, shredded zest and sugar into the microwave-proof bowl.
  8. Microwave on high for 20-40 minutes, uncovered, stirring every few minutes. How long it takes depends on how powerful your microwave is. I stir every 5-10 mins.
  9. While the marmalade is in microwave, sterilise the jars by pouring boiling water over them (lids too). I do this in the sink.
  10. Test whether marmalade has reached setting point – smear some onto the cold plate and let it cool. The setting point depends on whether you like your marmalade runny or rubbery.
  11. When marmalade is ready, spoon it into the jars, filling each one to about 1cm from the top. I use a tea towel to hold the jars as they will get hot.
  12. Wipe spilt marmalade from the outside/lips of the jars, then put the lids on and turn upside down for 5 minutes to seal and sterilise the lids. Then turn upright and let cool. <- That said, I am a bit slap dash, so I usually let the marmalade cool (put some kitchen towel over the tops to keep flies off if they’re around) and put the lids on once cooled.

I made some today, taking photos as I went. Here’s a montage of them.

Montage: Mary's Microwave Grapefruit Marmalade
Montage: Mary’s Microwave Grapefruit Marmalade