1. Coated cereal product, comprising the main cereal product and a coating mixture layer, wherein said coating mixture comprises: a sweetener, a hydrolyzed whole grain composition； and alpha-amylase or its fragment, while alpha-amylase or its fragment does not show hydrolytic activity against dietary fiber, being in an active state. The coated cereal product according to claim 1, wherein the coating mixture comprises a sweetener in the range of 20-60 wt.%. 3. Coated cereal product according to claim 1 or 2, provided that the coating mixture does not include beta-amylase. Coated grain product according to claim 1 or 2, further comprising a protease or fragment thereof, in a concentration equal to 0.001-5 wt.% Of the total whole grain content, while the protease or its fragment does not exhibit hydrolytic activity against dietary fiber, being in active state. 5. Coated cereal product according to claim 1 or 2, provided that the coating mixture does not include a protease. The coated grain product according to claim 1 or 2, wherein the coated grain product further comprises at least one of the following: amyloglucosidase or a fragment thereof and glucose isomerase or its fragment, while the amyloglucosidase or glucose isomerase does not exhibit hydrolytic activity in relation to food fiber, being in an active state. 7. Coated grain product according to claim 1 or 2, wherein the composition of hydrolyzed whole grains in the coating mixture has beta-glucan with a substantially intact structure compared to the starting material. Coated cereal product according to claim 1 or 2, wherein the composition is hydro1. Зерновой продукт с покрытием, включающий основной зерновой продукт и слой смеси для покрытия, где указанная смесь для покрытия включает:- подсластитель；- композицию из гидролизованного цельного зерна； и- альфа-амилазу или ее фрагмент, при этом альфа-амилаза или ее фрагмент не проявляет гидролитической активности в отношении пищевой клетчатки, будучи в активном сост
