Abstract: Described are compositions comprising a desired material, e.g., a soluble fiber, entrapped within a protein matrix, and methods of preparation and use thereof. In a preferred embodiment, the subject invention provides a method for entrapping a soluble fiber compound within a protein matrix, wherein the method comprises the following steps: (a) a soluble fiber compound is first mixed with undenatured protein to create a uniform dispersion, wherein the dispersion thus created comprises protein at a concentration of at least about 25% and soluble fiber at a concentration of less than about 75%; (b) the dispersion created in step (a) is then mixed with water and subjected to elevated pressures, wherein the pressures reduce the water content of the composition to less than about 50%, thereby forcing the protein and the soluble fiber compound into close molecular proximity; and (c) the dispersion is then subjected to heat of at least about 300.degree. F.