Words by Simon Difford
Photography by Difford's Guide
Oleo-saccharum is Latin for 'oil-sugar' and is the name given to the syrup made by using sugar's hygroscopic property to extract the fragrant natural oils in citrus fruit peels – most commonly lemons.
Oleo-saccharum is to a punch what a stock is to soup. Indeed, as Jerry Thomas wrote in his 1862 The Bartenders Guide "to make punch of any sort in perfection, the ambrosial essence of the lemon must be extracted."
Oleo has been used in punch-making since at least the first recorded mention in 1670 and the first known book on mixed drinks written in English, the 1827 Oxford Night Caps by Richard Cook, details how to "extract the juice from the rind of three lemons, by rubbing loaf sugar on them."
Oxford Night Caps published 1827
Jerry Thomas also instructs "by rubbing lumps of sugar on the rind, which breaks the delicate little vessels that contain the essence, and at the same time absorbs it." However, this doesn't work with modern sugar as it's not strong enough. As Wondrich found, "I've tried it with every kind of modern sugarloaf, cube and crystal I could procure and only ended up with a mass of crumbled, faintly scented sugar and a lemon undimmed in its yellowness. In this, our ancestors had the advantage on us."
Despite this, sugar is still used to extract citrus oils from their skin to make oleo-saccharum.
How to make oleo-saccharum
1. Buy preferably organic UNWAXED lemons (or other citrus fruit). Lemon works best in oleo-saccharum but oranges, especially blood oranges, also work well and are often combined with lemon.
2. Wash your citrus fruit.
3. Peel unwaxed lemons (or oranges, grapefruit etc) with as little of the white pith as possible on the peels and place in a Mason/Kilner jar. (If using 4 lemons then a 1 pint jar is plenty large enough.)
4. Measure 45ml / 1½oz of caster sugar per lemon used and pour into Mason/Kilner jar to cover lemon peels.
(peel of 4 x lemons = 180 ml / 6oz /small espresso cup of caster sugar)
5. Seal jar, shake and leave overnight. Occasional stirring helps.
6. The clear citrus oil syrup found floating on top of the sugar in your jar the next day is pure oleo-saccharum and it tastes divine. However, as you'll see there is precious little of it, and undissolved sugar remains. So, dissolve the remaining sugar and lengthen your oleo-saccharum by making an oleo-saccharum shrub (non-vinegar shrub or sherbet) as follows.
7. Add the same volume of lemon juice (or other citrus used) as you did caster sugar (in step 4) to the oleo-saccharum in your Mason/Kilner jar.
(peel of 4 x lemons = 180 ml / 6oz / small espresso cup of lemon juice)
8. Reseal jar and shake until sugar has dissolved. Now you have an oleo-saccharum shrub. If making a punch, pour this into your punch bowl, peels and all. Or refrigerate until required and store for up to four days.
If you have a vacuum sealer than try Jeffrey Morgenthaler's technique for making oleo-saccharum:
1. Muddle citrus peels with caster sugar in bowl.
2. Pour muddled peels and sugar into vacuum bag, remove air from bag and seal.
3. Leave to infuse for at least 6 hours at room temperature (preferably 12 hours) for the sugar to leach out and absorb the lemon oils.
4. Then date and refrigerate the sealed bag until required (within a week).
Tips & further info
Whichever of the two above methods you use, avoid the white pith when zesting citrus fruit and consider using a microplane zester rather than a peeler - the finer zest presents a larger surface area for the sugar to leach oils from although the oleo produced will require fine straining.
For more information on oleo-saccharum, see Punch: The Delights (and Dangers) of the Flowing Bowl by David Wondrich and JeffreyMorgenthaler.com.