Xanthan Gum and Strawberry Milkshakes

Can anybody guess what this is?

Water, cellulose, sugars (fructose, sucrose, glucose, maltose), oligosaccharides, starch (amylose, amylopectin), citric acid, malic acid, lactic acid, alcohols, aldehydes, ethylene, aromatic sulfur compounds, tomatine, furaneol, glutamate, carotenoids, lycopene, glutation, vitamin C, vitamin A, potassium, fatty acids and acyglycerols (one or more of the following: myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, arachidic acid, behenic acid or other free fatty acids), phospholipids, phytoene, phytofluene, tocopherols, sterols.

No? Me neither. It’s a tomato. Kind of shocking when you look at it, but at the same time unsurprising: food is just made up of chemicals.

It’s harder for me to think of food in this way, as atoms, molecules, and compounds, as chemistry is an area I don’t know a lot about. When food says “no additives or preservatives”, I just assume these “additives” and “preservatives” are undesirable to consume, without a second thought. But when I do stop to think about it, I do wonder: salt, vinegar and lemon juice are all preservatives, and we have these all the time. So which preservatives are the ‘okay’ ones, and which ones are the ‘bad’ ones? Perhaps we’ve just given bad press to anything that sounds science-y in our food.

Xanthan gum is a victim of this bad press, I feel, and the name starting with an ‘x’ hardly helps. It’s produced by the fermentation of sugar by the bacterium Xanthomonas campestrisin a similar way to how Saccharomyces cerevisiae (common yeast) ferments sugars to produce alcohol, or in bread-making. You could even call Xanthan gum a natural ingredient.

The gum produced by the bacterium is used as a thickening and stabilising agent, with applications like gluten-free baking, keeping the oil and vinegar together in a vinaigrette, or thickening sauces without using a roux. The Kitchen as Laboratory use it, along with nitrous oxide, to create the perfect sponge cake texture. It is usually used at only 0.5% of the volume of the liquid, such is its thickening power. For me to see the benefits of using Xanthan gum, though, like with the Balsamic Caviar it was important to have an application that would be useful, and not just novelty, as some molecular gastronomy experiments can be.

My desired use of Xanthan gum was in a strawberry milkshake. I personally like really thick milkshakes, and the solution to this is usually “add loads of banana”. Of course, the problem is that the milkshake just ends up tasting like banana. What’s more, if you’ve started off with a more delicate flavour, like strawberry, the banana can be so overpowering, you forget what fruit you put in to begin with. So, hopefully, with the addition of Xanthan gum, I could create a nice thick milkshake, tasting solely of strawberry, to go with the nice weather we are beginning to have.

So, to test the thickening effects of the gum, I made a simple strawberry milkshake recipe below, firstly without the Xanthan gum, so that I could get a base for comparison. The taste of the first batch was nice, but the texture was thin and sloppy, almost like drinking strawberry milk. Putting the Xanthan gum in, though, and it was a different story. A nice thick milkshake had been produced, tasting entirely of strawberry, exactly what I was looking for. The change in thickness really was remarkable, just caused by putting the gum in. Another great result for molecular gastronomy; an application where traditional methods would have struggled. All that’s left now is to enjoy the leftover milkshake, and to bring on the summer.

Strawberry Milkshake

300g strawberries
1 tbsp sugar
250ml milk
6 ice cubes
1g Xanthan gum

1. Put all the ingredients in a blender. Blend.

The finished milkshake, with Xanthan Gum. It’s hard to see the change in viscosity in a photo, but this was one thick milkshake.


2 Comments (+add yours?)

  1. Joe
    May 23, 2012 @ 11:04:30

    Alternative (unhealthy) solution: replace the ice and sugar with loads of vanilla icecream. Though to be fair, the icecream probably has xanthan in.
    I used to make one of those every day while my parents had strawberries in the garden.


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