For ➑-➓ jars*18 large Persian limes (-/+ 1.5 kg), peeled, zest cut into thin strips 5 cm long (or a mix of limes & lemons)
1.8 l water
3 kg sugar
Cut the peeled limes in half and squeeze the juice. Set the juice aside.
Scrape the pulp and seeds from the lime halves. Place in a cheesecloth bag. Place the cheesecloth bag, zest, juice and water in a large saucepan, then cover them and soak overnight, or for about 8 h.**
Bring the water mixture to a boil*** and cook about 2 h, until the peels are soft. Remove the cheesecloth bag. Add the sugar to the pan and stir to dissolve. Boil, stirring often****, until a cooking thermometer reaches 180°C.
Ladle slightly cooled marmalade into clean jars*****, leaving 0.5 cm of headspace. Cap and seal. Process for 10 m in a boiling-water-bath canner.
*Or for ➌-➍ jars: 6 large limes, 40 cl water, 750 g sugar, (a pinch of salt).
**Necessary to soften the zest.
***Limes can be reluctant to set. Add a small quantity of bicarbonate of soda to the mix before cooking: (less than levelled) 1 ts per 1 kg lime or lemons, or ½ ts for a 50/50 mix with orange or mandarine.
****Avoid stirring for 20 m after sugar is disolved for a clearer marmalade. Stirring might avoid burning though.
*****Sterilise the jars by placing them in the microwave on high for 6 m or about 12 m into the rolling boil. The jars should be hot when pouring the jam in, otherwise they will crack. Sterilise the lids by placing them in a saucepan of boiling water for 5 m.
******Use microwave for small quantities: 1 large piece of citrus fruit or 2 small ones (orange, lemon, tangerine, lime, etc). Wash it well and cut into chunks, skin and all. Remove all seeds and coarsly chop. Measure fruit and add equal amount of sugar to 2 l Pyrex measuring cup or similar size bowl. Stir to blend. Cook on 100% power for 8 m, stirring occasionally. Cook until thickened. Pour into jam jar, cover and refrigerate.
Lime marmalade was popularized by Rose & Co., a company that started preserving lime juice imported from the West Indies (Dominica) in 1867, to make alcohol free lime juice cordial, a concentrated drink to prevent scurvy, mainly in the British Navy. The peel and flesh that was left over from making the lime juice was soon used to make lime marmalade, as already practiced by West Indian cooks. The now world-famous Rose's lime marmalade was introduced as a luxury alternative to traditonal orange marmalade.
