Disclosed are an in-line direct cryogenic method and system for cooling heated fluid food products, such as sauces. The method includes injecting cryogen directly into the fluid to be cooled while the flow rate of the fluid to be cooled is adjusted in response to downstream temperature measurements and while maintaining the injection rate of the cryogen into the fluid. According to the method the flow of the sauce is adjusted during the flow of the cryogen to achieve process stability, product uniformity and efficient use of the cryogen.