Spray a large skillet with nonstick spray coating. Preheat skillet over medium heat. Add chicken. Cook over medium heat for 8 to 10 minutes or until tender and no longer pink, turning to brown evenly. Remove from skillet; keep warm.
Meanwhile combine apple juice, bouillon granules, cornstarch, and, if desired, mint. Add to skillet. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. Stir in grapes and heat through. Serve over chicken. Makes 4 servings.