Rhubarb Extract (Juice)
Do you ever have one of those ideas that is so simple you don’t know why you didn’t think it sooner? A versatile rhubarb extract for cooking was just such an idea that occurred to me sometime last week. I took to the internet to see if somebody else had made similar or tested it out but all I could find were syrups or juices designed to mix in cocktails or sparkling water. So, I told myself, it’s either because it doesn’t taste good or because it’s too much work for too little return. But I thought I’d give it a go anyway and I’m so glad I did.
Let me summarise; my aim was to make an extract that could replace citrus, in particular lemon or lime juice, in any recipe. I wanted to replace them because they aren’t easily grown in Britain without a lot of extra work, so most are shipped in from Spain or much further away. So what naturally grows on British soil, has a similar flavour profile to lemons (highly acidic), and can be processed and preserved? It also happens to be that a lot of Farmer and Chef readers have been asking for recipes that use rhubarb but without sugar, so this seemed like the perfect answer to both. And the best part, all you need is a saucepan, scales, a knife and a sieve. No fancy blast freezing or centrifuge equipment required. Oh and did I mention that it only takes 1 hour; most of which is just leaving it to reduce?
Applications for this extract: Any recipe that calls for a dash of lemon juice, from cake to stir fry, you can use this instead. It does have a different taste because rhubarb doesn’t share the same aromatic or flavour compounds as citrus, but it brings it’s own distinct characteristics whilst broadly playing the same role in a recipe by fulfilling the acidic profile to balance or enhance other elements of the dish. As an example of this, I’m writing a recipe for a seasonal paella that pairs purple sprouting broccoli, wild garlic and saffron with a dash of rhubarb juice to finish. And believe me, it is gorgeous! So let’s crack on with the recipe.
Rhubarb Juice Recipe
550g Rhubarb, roughly chopped
750ml water
(Yields roughly 250ml rhubarb juice)
Step 1.
Clean and chop up your rhubarb stalks and pop them in a pan with cold water. Bring to the boil over a high temperature, then reduce to simmer for 20 minutes.
Step 2.
Pass the juice through a sieve and give the rhubarb pulp a good pressing until it looks visibly drying (more like a ball of string). You can keep this rhubarb pulp to cook into this rhubarb ketchup recipe or bake it into a crumble with apples and seasonal berries.
Once you have collected all of your juice, return it to the hob in a clean saucepan and continue to gently simmer for 40 minutes (or until roughly halved in volume). During this time, foam and skin might form on the surface of the liquid. You can either remove this with a spoon or use a technique called a cartouche, wherein you cut a piece of baking parchment into a circle the same size as your saucepan with a small hole in the centre. Lay it flat over the surface of your juice and allow it to stay there as the juice cooks. The parchment forms an artificial skin that stops the forming of a natural skin. But this will slow the reduction of the juice so bare that in mind when bottling up.
Step 3.
Once the juice has reduced to the right concentration, sterilize a bottle and carefully pour it in whilst it is still hot. Cap the bottle and store in the fridge. Alternatively, you can add the bottle to a bath of boiling water and simmer for 10 minutes to heat treat the juice. This should make it shelf stable at room temperature until opened, at which point, store it in the fridge for up to a month.*
*I am yet to keep my rhubarb juice for this length of time so cannot vouch for how well it ages. I am simply going off of how long lemon juice lasts when freshly made but I will update this recipe as and when I find out more.
I hope you enjoy this vibrant, acidic cooking ingredient. I would love to hear about ways you have incorporated it into recipes, from drinks and cocktails, to cakes to meals to salad dressings. My next step is to try out a fermented kombucha version.