These jellies are basically the point of grapefruit, at least in my opinion. I find grapefruit far too bitter to eat, but the bitterness and sourness help the pectin to set the jelly, and the resulting confection is just sweet enough, with a lovely grapefruit flavour and only a hint of bitter pith. If you like other citrus but have never liked grapefruit, give these a try. You’ll be surprised at how nice they are.
This recipe is actually extremely easy to make – the biggest difficulty in my experience is finding the right kind of pectin. Well, that and not having exploding thermometers or scales which spontaneously malfunction. The pectin you can buy at most supermarkets or health food shops is for jam – confectionery requires a stronger pectin. My pectin is labelled Classic CS 502, with a degree of esterification that is 58-64% and is designed for a soluble solids range of 68-80% and a pH range of 3.0-3.6. I’m afraid I have very little idea what that means (clearly I need to read more of that food chemistry book), but it might give you something to look for on the packaging.
You also absolutely require good scales and a candy thermometer for this recipe. I recommend avoiding glass thermometers – they can shatter, and there’s nothing worse than having your jelly all ready to pour into the tin and then realising that you only have half a thermometer and the other half is somewhere in the gel... especially when this was the first time you actually found the right pectin and got the mixture to setting consistency…
Your Shopping List50 g + 350g sugar (plain white sugar is best here) 20 g pectin zest and juice of 1 medium grapefruit (about the size of a largeish orange) 175 g glucose syrup (I think this is the same as corn syrup – it’s a clear, very viscous, very sweet liquid derived from corn) 10g citric acid solution (5 g citric acid dissolved in 5g just-boiled water) caster sugar, to coat
Now what do you do with it?
Mix the pectin with 50g sugar, and put in a small-medium saucepan with the grapefruit zest. Put the saucepan on your scales and set to 0, then pour in the grapefruit juice, whisking like mad – pectin likes to clump up. Pour in cold water until the scales read 250g, still whisking madly.
Bring to a boil over low heat, whisking until everything is smooth. Theoretically one is supposed to simmer it for 2 minutes here, but by the time I’m done whisking it, I don’t usually bother.
Add sugar and glucose syrup and stir in briefly to disperse. Incidentally, the easiest way to get glucose syrup out of a jar is with a spoon (or better still, fingers) that you have dipped in cold water – it doesn’t stick as much then.
Boil the syrup without stirring until the temperature reaches 108°C. While you’re waiting for it to get there, line a 19cm square tin with baking paper – this jelly sticks like you wouldn’t believe, so I usually do two layers at right angles to each other.
When the syrup reaches 108°C, take it off the heat immediately, and stir in the citric acid solution as quickly as possible, then pour the lot into the tin. It will start solidifying as soon as you add the citric acid, so you need to be fast.
Let sit at room temperature for at least 3 hours, then cut into cubes or diamonds (which is harder than it sounds – this jelly is quite tight and difficult to cut) and toss in caster sugar to coat.
Eat, with delight.
This recipe is obviously vegan and gluten-free, but if you’re trying to avoid sugar I’m afraid you are out of luck. It keeps for months – I find the consistency of the jelly softens a little over time, but the outside becomes a little harder.
You can make it with any kind of citrus fruit – you just need to adjust things so that you get about 60-100g of fruit juice. It’s especially good with blood orange and pink grapefruit, and wonderful with kumquat, apart from the fact that zesting and juicing kumquats is a very efficient route to insanity. You’ll find that the consistency of the jelly varies with the acidity of the fruit. I’ve also made these with apple juice (rolled in cinnamon sugar) and with pomegranate juice – it will work with any nice, acidic fruit, but if you use just fruit juice, it burns easily.