Peel the rind off the grapefruit and lemons and place into a blender

Chop finely and set aside

Quarter the grapefruit and halve the lemons

Place into the blender in batches and roughly chop

Put the pulp into a large sauce pan and add the water

Over a high temperature, bring to the boil

Reduce the temperature and simmer for 45 minutes

Drain the pulp through a fine sieve, leaving it to drip for 30 minutes *

Using the back of a spoon, press the juice out of the pulp

Discard the pulp and measure the juice

Top up to 500mls if necessary with water **

Return to a clean sauce pan and add the rinds

Cover and simmer over a low temperature for 15 minutes

Add the fructose and stir until dissolved

Increase the temperature and bring to a boil

Leave uncovered to boil for at least 10 minutes so that you achieve a set temperature of 105° Celsius

Remove from the heat, carefully skim off any scum and leave to stand for 15 minutes

Pour into a sterilized glass jar and leave to cool completely before placing the lid on the jar

Can be stored unopened for 12 months - refrigerate once opened