The present invention relates to a new dog food flavoring agent and more particularly to dog foods having increased palatability due to the use of this flavor and methods for producing the dog foods in increased palatability. 
There is a continuing effort being made to increase the palatability of dog foods, while at the same time maintaining their nutritional value.  While, by itself, the development of nutritious dog foods is quite well understood and poses few problems to the art, there is a continuing problem of making these formulations palatable.  Where an offered food is unpalatable, a dog may pass it up and thereby not take advantage of its nutritional value. 
Many attempts have been made to obtain increased palatability of pet foods by the addition of a variety of materials.  For example, it has been suggested that licorice and licorice-type products may provide palatability increases in dog foods.  Our tests with licorice indicate, however, that they are not accepted by dogs.  Among the known licorice flavored materials is glycyrrhizin, as well as its ammoniated and acid forms.  It is on the premise, wrongly according to our tests, that dogs like licorice that ammoniated glycyrrhizin has been suggested by its manufacturer for use in dog foods. 
Ammoniated glycyrrhizin is perhaps the sweetest chemical processed commercially that is prepared from essentially natural sources, and has a sweetness value about 50 times greater than that of sucrose.  Glycyrrhizic acid is obtained in about 90% or more purity by grinding the root glycyrrhiza glabra, extracting the ground material with hot water, and treating the extract to recover the acid insoluble fraction containing the glycyrrhizic acid.  Glycyrrhizic acid can be ammoniated, to provide ammoniated glycyrrhizin, by replacing one or more of the three acid hydrogen ions with ammonium ions.  Ammoniated glycyrrhizin, therefore, ranges from a mono-ammoniated product to an essentially fully (tri) ammoniated product and mixtures thereof. 
It is primarily for the licorice flavor of ammoniated glycyrrhizin that it has found widespread use as a flavoring agent in, for example, confections.  Because of the licorice flavor, however, ammoniated glycyrrhizin has not been widely used alone as a sweetening agent except in some licorice-flavored confections, since the amount required for sweetening also imparts the characteristic licorice flavor. 
In U.S. Pat.  No.  3,282,706, it was disclosed that ammoniated glycyrrhizin potentiates the sweetness of sucrose in sucrose-containing foods, confections and beverage at levels which do not appreciably impart the licorice flavor.  By "potentiate" was meant that the sweetness value of a combination of sucrose and ammoniated glycyrrhizin was over and above the sum or mere additive effects of the known sweetness values and was, therefore, the result of synergism between sucrose and ammoniated glycyrrhizin in certain relative proportions of one to the other.  The critical levels disclosed in that patent were from 0.2 to 2.2 parts by weight of ammoniated glycyrrhizin per one hunderd parts by weight of sucrose.  Thus, this patent discloses that at levels of ammoniated glycyrrhizin below 2.2% (22,000 parts per million) based on the combined weight of sucrose and ammoniated glycyrrhizin, no licorice flavor was noticed and, at levels below 0.2% (2,000 parts per million) of ammoniated glycyrrhizin based on the combined weight of it with the sucrose, no synergism was noticed.