Xanthan Gum
What it does
Thickener/stabiliser.
How it's made
Made by bacterial fermentation of sugars.
Xanthan gum is a natural thickener and stabiliser produced by fermentation, used across an enormous range of foods — dressings, sauces, gluten-free baking, dairy and drinks — because a tiny amount thickens strongly and keeps mixtures stable, and it holds its viscosity in acid, salt and heat.
It is made by fermenting sugar with the bacterium Xanthomonas campestris. The bacterium is grown on a glucose or sucrose feedstock in fermenters, and as it grows it secretes xanthan gum into the broth. The gum is then recovered by precipitating it with alcohol, and the solid is dried and milled.
The dried xanthan is purified and standardised into a cream-coloured powder. Its standout feature is that it thickens dramatically at low levels and stays stable across a wide range of conditions, which is why it is a mainstay of gluten-free and convenience foods; it is produced from a food-grade fermentation and is suitable for vegetarians and vegans.
Possible reactions
Large amounts can cause bloating; corn-derived (coeliac usually fine).