I am not an expert, either -- I'm still learning -- but what you need to read up on is called "baker's percentages."
SCALING RECIPES USING BAKER'S PERCENTAGES
Bakers' percentages are very handy if you want to scale recipes up, down, and sideways. If you know the percentages, you can start with any amount of flour you want and figure out the rest of the ingredients by doing a little bit of math.
Let's try this with a real recipe.
My standard, everyday white bread recipe breaks down to the following percentages:
- Bread flour: 100%
- Water: 67%
- Sugar: 4%
- Yeast: 2%
- Salt: 2%
- Olive oil: 4%
So let's say I start with 12 ounces of flour on my scale. To calculate the rest of my ingredients, I first divide the amount of flour I have by 100, giving me 0.12 ounces. Now all I have to do to figure out the rest of my ingredients is to multiply them by their various percentages. So, for example, the water recipe is 67% water. Multiply 67 by 0.12, and I get 8 ounces (rounded from 8.04 ounces).
Do the same math across the board (rounding to the nearest 0.05 ounce), and you get the following weights:
- Bread flour: 12 ounces
- Water: 8 ounces1
- Sugar: 0.5 ounces
- Yeast: 0.25 ounces
- Salt: 0.25 ounces
- Olive oil: 0.5 ounces
ARRIVING AT A SPECIFIC DOUGH WEIGHT
What if you want to go the other way? Say you know that you want a pound of finished dough. How would bakers' percentages help you figure out how much of each ingredients to use? First, you'd start by adding up all of your percentages. For the white bread, that's 179. Next, divide the weight of the final dough you are trying to achieve by that number to give you the weight of a single unit.
So four a 16-ounce (1 pound) ball of dough, each unit of weight should be equal to 16 ounces/179, or 0.089 ounces.
Now all you have to do is multiply that unit by each of your percentages. So flour, for example, is 100% of the recipe. 100 x 0.089 = 8.9 ounces total. Using the same math for every ingredient, you get the following measurements for a one pound ball of dough:
- Bread flour: 8.9 ounces
- Water: 6 ounces
- Sugar: 0.35 ounces
- Yeast: 0.175 ounces
- Salt: 0.175 ounces
- Olive oil: 0.35 ounces
Best Answer
You seem to have misunderstood something, or been misinformed.
The only reason that xanthan gum does something in gluten-free bread is that gluten-free bread cannot trap any air for rising and is a very moist and dense thing on its own. The xanthan gum is a kinda OK gluten replacement, imitating its role somewhat.
It has no such effect in normal dough with gluten. Indeed, it might make it less airy and generally worse, like dough which has too much gluten added. Or it might have so little effect as to be unnoticeable. But it certainly has no mechanism by which it would improve your normal bread dough.
I cannot say much about the cookies, but it might be that they needed additional binder. This depends on what kind of cookie it was, but some kinds are full of filler and very prone to crumbling, xanthan may help with that. Or somebody backconverted a gluten free recipe to a wheat one and didn't understand that this makes the xanthan obsolete. There are many possible explanations.