Is it okay to use whole wheat flour instead of vital wheat gluten for a recipe?. Would there be any noticeable flavor and texture changes?
These are two related, but different products.
Gluten is protein that is formed from two pre-cursor proteins, glutanin and gliaden, found in wheat flour in the presence of water and under enzymatic activity.
It forms resilient stretchable networks which give yeast raised bread its structure.
Whole wheat flour is... well... whole wheat berries, ground up. It is mostly starch, but contains all glutenin, gliaden, and the necessary enzyme to create gluten, which forms naturally when the flour is moistened, if given long enough or kneaded to accelerate the process. However, even a very "strong" flour (bread flour) will have no more than about 10%-15% percent protein by weight, so it cannot form more than that amount of gluten.
Vital wheat gluten is essentially concentrated, powdered gluten, without the rest of the parts of the wheat berry.
They are not freely interchangeable, as the gluten does not bring the starch, bran, and other components that flour does. You may, in specific recipes, be able to use just gluten, but not in the general case. And even if substitution is possible, you would have to determine the correct ratio to achieve the desired outcome.
Using vital wheat gluten in lieu of whole wheat flour, in most applications, will either fail completely (no thickening from starch, as in a gravy), or be dense and rubbery, and practically unpalatable (as in a bread).
You can make Seitan from wheat flour by forming it into a dough, then rinsing away the starch. Making it from vital wheat gluten is faster, but wheat flour is a more common staple and you might feel better about making it from this raw ingredient.
Check out this link:
"The main objective when making seitan from whole wheat flour is to separate the starch from the gluten through a series of rinses and letting the water wash the starch away from the gluten."