Lemon curd
Like most people I always associated lemon curd with England, it is a quintessentially British conserve. Unfortunately while living there and sticking to the strict policy of only using ingredients which grow on the island we never really used it.
Lemons travels pretty well, or maybe was a throwback to a time when glass roofed walled gardens were envogue. canned good also travel very well I guess.
I made fruit curds at the moorcock using sea buckthorn (a berry which grows prolifically at the seaside and tastes like passion fruit) and from fruit vinegars like rose, rasperry and rhubarb.
The only citrus we used was lime chutneys and salt preserved lemons left over from the bar, (I cheated during lockdown and bought a case of organic yuzu from France when we were a Chinese takeaway, for the nations favourite lemon chicken).
Its mainly since being back in Australia where every second garden has some form of citrus tree hanging over its fence that I have come around to using it again.
Over the next period there will be an abundance of citrus recipes up on here, will be a winter theme.
Starting with the British-ish pantry staple lemon curd.
It is traditionally a preserve, something that would sit in a cool cellar for months, There are a lot of recipes for canned lemon curd online which should pretty well last forever if done properly.
Canning takes the contents of a sealed container up to 120 degrees C which will destroy any and every living thing inside the jar. It clearly works but it does takeaway some of the silkyness and flavour you achieve if you leave out the canning step. Because if this I poach the curd once it is cooked in jars. I use a water circulator to achieve an accurate temperature, so I can rely on the curd being taken to a safe temperature without over heating the curd and changing its texture.
This means the curd can be kept in a cool place for about a year unless the jar is opened, at that point you have to keep it in the fridge and it will last about 4 weeks.
There are 4 ingredients in the curd, sugar, eggs, lemon juice and butter.
The reason for each ingredient other than flavour is
Eggs make the rich body of the curd and thicken to make it spreadable.
The lemon juice adds acidity which denature the eggs proteins and stop it from becoming lumpy scrambled eggs. The acidity also slows bacterial growth after the cooking process
The sugar stabilises the mixture by curing the eggs and helping the proteins to rebond and re structure into a softer texture.
The butter softens the bonds between the protein and sugar giving a smoother texture, it also stops the custard mix oxidising and increased the shelf life.
Because of all these characteristics there is an order in how to add them together. If you dump them all in a bowl and cook them the curd will be fine, but it can also cause problems.
The best way to incorporate the ingredients is-
In a large metal bowl mix your sugar, zest and eggs until smooth. This will cause the sugar to cure the eggs and allow the sugar to begin dissolving. As the sugar dissolves into the eggs it will dilute the proteins and start to denature them.
Next add your lemon juice, if you add the lemon juice straight to the eggs the eggs will begin the coagulate and will not bond as well during the cooking. - acidity makes protein unravel and denature. Which helps to make a smooth silky curd, however if the lemon comes into contact with just the eggs the acid will be too strong and the eggs can become curdled.
Heat the lemon and egg mix in the bowl over a pot of boiling water storing constantly with a rubber spatular.
Once the mixture begins to thicken begin adding cold butter a little at a time. The cold butter will melt into the mix once you cannot see the butter add a few more squares until all in incorporated.
Cook the mix out until it has become thick enough to coat the back of a spoon without running off.
If you understand the way the ingredients interact you can understand why the mix can be taken to high temperatures without separating.
When I jar the curd to preserve I heat the water to 85, and heat them for 1 hour.
Its a high enough temperature to kill off almost all the high risk pathogens which we look out for in the commercial kitchen, with the exception of botulism spores, however it is a high enough temperature to kill the living botulism and the acidity in the curd is high enough to stop the spores from growing.
Recipe.
Lemon curd approx 4 lemons
Zest and juice of 4 lemons (240g lemon juice)
200g caster sugar
3 whole eggs (180g)
1 egg yolk (18g)
100g butter (diced)
In a large metal bowl mix together sugar, eggs, yolk and lemon zest until you have a homogenous mixture.
Add lemon juice and place over a pot of boiling water mixing constantly with a rubb
er spatular to avoid the mix scrambling.
Once mixture begins to thicken begin adding cubes of butter a little at a time until all the butter has been incorporated.
Continue to cook out the mix until it has become pale and thick enough to coat the back of a spoon without falling off.
You can choose to simply place this mix in a container in your fridge at this stage and it will last approx 4 weeks.
Otherwise continue to canning.
5. Pour curd mix into sanitised jars and seal immediately.
6. Submerge jars in a container of water with a immersion circulator set to 85 degrees C and set timer for 1 hour.
7. When the hour is up remove the jar from the water bath. Place in a cool dark place for up to 1 year.
8. Once the jar is opened it must be refrigerated and consumed within 4 weeks.
You can substitute different citrus ingredients into your curds, it is a good idea to keep some of the lemon in the mix as it typically has a lower ph than oranges or grapefruits.
An example I use 120g lemon juice and 120g blood orange juice to make an orange curd.
Or 100g lemon juice and 140g mandarin/clementine juice for a more tropical version.
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