I’ve been pondering the perfect lemon sorbet. It has to be tart, but not too tart that it puckers the lips and leaves an acidic aftertaste in the mouth. Solving the mysteries of the balance between sweet and sour has kept me occupied for a little while – plus numerous trials resulting in various degrees of lip-puckering sorbet. Luckily, we have a good supply of lemons from our trees.
First, let me stress that not all citrus are the same. Their acidic levels are different, measured by pH numbers, and variable by age of fruit, growing conditions, variety, etc. For example, both my sour oranges and mandarins from our garden are on the higher acidic side. The pH scale ranges from 0 to 14 (with 7 at mid-point being neutral). Any number below 7 is acidic and above is alkiline. The following is a handy chart of the approximate pH in common citrus that will be useful in future citrus sorbet making – starting from neutral and descending – the lower on the chart, the more acidic.
You can see that lemon is the most acidic – near the bottom. So, it isn’t simply a matter of substituting lemon juice for the mandarin or orange juice in my recipe for sour orange or mandarin sorbet. Experimentation with your ingredients is the best – hence the numerous batches of puckering sorbet before we reached the optimum balance between tart and sweet.
My recipe is based on Nick Palumbo’s lemon sorbet in Gelato Messina, but I’ve added a bit more lemon juice for a more intense lemon flavour, but blended this with a small amount of fructose, which has a very high sweetness index.
- 240g lemon juice
- 10g Fructose
- 470g Water
- 175g castor sugar (Sucrose)
- 55g Dextrose
- 55g Maltodextrin
- 5g Stabaliser (xanthan gum or locust bean gum)
Juice your lemons and measure out the required lemon juice. Taste and if too tart, add the fructose – a little at a time. You may not need all 10g. The juice should be tart, but you should also be able to detect a little bit of underlying sweetness. Keep the juice cold in the refrigerator while you mix up the other ingredients.
Weigh and mix your other sugars (sucrose, dextrose and maltodextrin) and add the stabiliser so that everything is well blended. In a separate bowl, measure your water and heat for about 30 seconds to 1 minute in the microwave.
When the water is warm, remove and whisk the sugar mixture in, making sure no gel lumps form. If you are using xanthan gum, it will get in the warm water. If using locust bean gum, you will probably need to return the mixture to the microwave and heat until it begins to bubble. I tend to do this in short bursts, whisking after each time until it become thickened. Or, you can heat it in a double boiler on the stove.
Let this mixture cool before whisking in the cold lemon juice. Put the whole mixture back into the refrigerator overnight. Blend again with a wand blender before putting into your ice cream machine. Churn according to instructions.
When finished, put the sorbet in a container and place in the freezer for at least 4 hours until it firms up. To scoop, take it out of the freezer and place it in the refrigerator for about half an hour before serving.