One problem with being on a low-carbohydrate diet is how to thicken sauces and stews that ordinarily use flour. Stew without a thickener is really soup, in my book anyway. And sometimes I want stew, not soup.
That's when guar gum comes to the rescue.
Guar gum is a galactomannan, meaning it's a polysaccharide made from the sugars galactose and mannose. We can't digest the polysaccharide, although bacteria in our intestines may eat the stuff. Thus guar gum is classified as a fiber.
In India, where most of the guar gum in the world is produced from (surprise) the guar bean, the gum is used to reduce cholesterol. Like other fibers, it is also sometimes used to slow down digestion and hence reduce blood glucose levels a little. Like other fibers, it can make you feel fuller without additional calories. And like other fibers, it can help prevent constipation.
In the United States, guar gum is often used to make ice cream creamier, as it inhibits the formation of ice crystals (check the ingredients of ice cream). It's also used as a thickener in commercial kefirs and yogurts and other foods.
Unfortunately, the gum has also been found to be useful in "hydrofracking," the process of extracting gas and oil from rocks, and as a result the price has increased greatly.
Nevertheless, most of us will probably never use pounds of guar gum, as a little bit goes a long way, so the greater price should have little effect on our budgets.
Foods thickened with guar gum look as if they've been thickened with cornstarch: they have that shiny, transparent look instead of the more opaque look of a gravy thickened with flour. But for that reason, guar gum is the perfect substitution if you want to make a Chinese recipe with a thickened sauce.
It doesn't work as a coating in Chinese recipes, however. I've tried it and been most disappointed.
Although sauces made with guar gum resemble those made with cornstarch, the process is much simpler. This is because cornstarch isn't soluble in cold water. You have to disperse the starch in a cold liquid and then slowly heat it while stirring, so it doesn't clump.
Guar gum is soluble in cold water, so you can dissolve it without so much fuss. Despite this, it can clump if you add too much at once, so I keep mine in a spice jar with a sprinkle top, so I can shake a little into the food I want to thicken, stir a little, and then shake a little more if it's not thick enough. It does get thicker with time, so you don't want to add too much.
Sometimes I'm too lazy to be careful, especially when making custard. I adore custard, but the classic way to make custard is tedious. You have to heat the milk and eggs carefully in a double boiler while stirring and watching to make sure it doesn't get too hot. Then you're supposed to force it through a sieve to remove any lumps.
Not me. I've always just added the milk and eggs and boiled away until the eggs solidifed. Then I poured the mixture into a blender to get silky custard, albeit a tad thinner than when made the classic way.
Now that I'm on a low-carbohydrate diet, I don't use milk, which contains about 11 g of carbohydrate per cup. And custard made with cream is too thick for my taste. So I use nonsweetened almond or coconut milk instead.
With these milks, the custard is too thin, so I add guar gum. Sometimes I actually encourage it to clump by not stirring well, and then I pretend it's tapioca. I used to love tapioca.
So to me, guar gum is a winner. It thickens things more easily than cornstarch. It lowers cholesterol. It lowers blood glucose. The only thing it won't do is wash the pot after I've made the custard. Oh well. Nothing is perfect.