Rice flour doesn't have protein and its starch alone won't hold the cookie together. The crumbs would taste good, but they wouldn't hold together. That's what the xanthan gum is for. Xanthan gum is made by fermenting starch and sugars, usually by certain bacteria. Glucose and mannose sugars are tied together into long chains to make the gum.

Sometimes xanthan is made from wheat, in which case there still might be enough gluten to cause allergy problems. But it's usually made from corn.

The long chains of sugars absorb a lot of water, thickening any liquid they're in. Xanthan often is used in reduced-fat salad dressings and other fat-free products. It can thicken the liquid but still allow it to pour. It also makes dough sticky by holding onto both the liquid of the batter and wrapping around the sugar, chocolate chips, rice starch and other ingredients.

Xanthan is used in toothpaste, and it's the liquid thickener for people who have trouble swallowing water or thin liquids. It's good for that because it doesn't make the liquid cloudy the way flour or cornstarch would, and it has no flavor, so it doesn't change the taste of the food or beverage.

Xanthan is not digestible, which makes it a fiber. It can be a laxative for some people. That might be good if you're constipated, but it can be a super-laxative for some. So don't eat the whole package of cookies at once.

Q: What is swai fish? I just bought some because the price was good, but I don't know what it's like to cook.