Figure : Using the integrated gradients method, atoms can be highlighted according to how important they were for classification. Positive contributions regarding the assigned label are highlighted in green, and negative ones in red. p-Anisic acid ( ) is correctly classified as sour (pK a 4.47) and yields methyl anisate (2) after esterification, which is found in star anise and has a sweet and fruity flavor. Catechin (3) is a bitter member of the polyphenol subgroup called flavenoids. The amide ( ) is an analog of an umami flavor enhancer called cyclopropanecarboxylic acid (2-isopropyl-5methyl-cyclohexyl)-amide. Saccharin ( ) is a common artificial sweetener and 2,5-dimethyl-4-propyloctane ( ) is a water unsoluble alkane that is not known to elicit any taste.