Ice cream: Smooth talking
Can you provide some advice for my creamy conundrum? I was given a fancy ice cream maker with a compressor for Christmas and have been having great fun experimenting with different flavours. Although the resulting ice cream tastes great, the texture is often a little icy. I’ve been experimenting with using guar gum and xanthan gum to stabilise the ice cream but the results are a bit hit and miss. I generally use an ice cream base of 2 cups milk, 1 cup cream, ⅔ cup sugar plus flavouring. I boil fresh fruit into a thick paste or syrup for the fruit flavour, adding one cup of the strained mixture to the base. Which gum is best to use for a creamy result - guar, xanthan or both? And what quantities should I add to my recipe? Should the gums simply be beaten into the chilled mix, or dissolved in a little hot milk first? Any tips for top ice cream (bad pun intended) would be appreciated.
Lucky you — what a great Christmas present, especially with the gorgeous summer New Zealand has been enjoying. You must have been churning like there’s no tomorrow.
Many people reading this will be wondering what on earth guar gum and xanthan gum are. So let’s deal with that first. They are both bought in powder form so I don’t know why they’re referred to as gums. In commercial food manufacture they are both used to stabilise, emulsify or thicken foods so that the salad dressing doesn’t split in the bottle, or your gluten-free bread sink. In the former they cause the fat (oil) and liquid (vinegar) to stay closely connected, as though emulsified in suspension, to give a consistent flavour and texture that doesn’t separate. In the latter it replaces the gluten (protein) in the bread which holds the dough together and in turn traps air causing it to rise and stay upright.
As to where these two gums come from — they couldn’t be more different. Xanthan gum is a secreted polysaccharide produced by a bacterium. It’s not officially an emulsifier but serves the same purpose in liquids and is used in anything from toothpaste through to oil drilling rigs. That may put you off wanting to use it in your food — but according to food technologists its properties are incredibly useful. It’s worth pointing out though that it can be allergenic to some people as it can be produced from corn, wheat, soy or diary. Guar gum on the other hand is made from guar beans, which are mostly grown in India. Like xanthan gum, it is a stabiliser and thickener but also works more like an emulsifier in that it prevents the liquids and fats from separating. And like xanthan it’s also used in drilling for oil to allow the soil, oil and water from the earth to be whisked up on to the surface.
It’s not often that I’ve used either gum in my ice cream making but I have played with them both as I find the science fascinating. I make ice cream the old fashioned way using egg yolks to make a custard as you would a creme anglaise. Yolks contain lecithin which works to emulsify the fat and the water that is present in both full fat milk and cream. Without egg yolks the churned mixture becomes very icy as the water molecules begin forming ice crystals as the mix freezes. If I’m making a particularly fruity ice cream I’ll also add glucose syrup to the warm custard, because glucose (along with golden syrup, honey, sugar and alcohol) all help to prevent ice crystals forming which is not what you want in an ice cream. A nice smooth and creamy frozen dessert is what we’re after. If I add too much glucose then the ice cream may not set; too little and it becomes icy. For those who don’t want a rich ice cream, using one of the gums is one way to get around this icy dilemma.
Guar gum, in my opinion, is far better to use in ice creams than xanthan, which I think is better used in baked goods like breads. The only time I’d suggest you use xanthan over guar in a frozen dessert is if the dessert contains a lot of citrus juice, which can cause guar to be less effective. A lemon gelato or sorbet would be one such example.
A little also goes a really long way — you’ll need around ½ teaspoon per litre of sorbet base. If you find it still stays icy then increase a little each time. The best way to incorporate it into a fruity sorbet would be to put the fruit in a blender with the powdered gum and blitz it for at least 20 seconds.
And my one last tip for icy ice creams is that the more you take it in and out of the freezer the more icy it will become — the action of melting and refreezing is a no no!
In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. If you’re stumped over something food-related, send your question to firstname.lastname@example.org and keep checking in for answers. You can read more on Peter on his website, have a read of his Ask Peter articles or check out his recipes on our site.