The disclosure relates to a method of fortifying a processed cereal piece with external fiber comprising: providing said processed cereal piece； using coating means, accritively coating said processed cereal piece with between 5.0% and about 50% w/w of the coated cereal piece with said fiber, wherein the step of coating comprise adding said processed cereal pieces into a coating means； separately adding fiber and an adhesive liquid to said coating means； and accritively increasing fiber content on the surface of the processed cereal piece in the coating means, wherein 30 grams of the coated processed cereal piece have less than or equal to 100 calories and shows substantially no clouding in 250 ml. cold water after 10 seconds.
