Final answer:
The incorrect match is 'bitter taste: elicited by metal ions' as bitter taste is typically elicited by a range of complex organic compounds that interact with G protein-coupled receptors, not simply by metal ions.
Step-by-step explanation:
The incorrect match in the list provided is 'bitter taste: elicited by metal ions'. Bitter taste is actually elicited by a large diversity of molecules. These molecules typically bind to G protein-coupled receptors on the gustatory cells in the tongue. There are many different bitter compounds, and they can have varying effects on these cells, such as depolarizing or hyperpolarizing them, or increasing or decreasing G protein activation. On the other hand, it's commonly accepted that bitter foods include coffee, unsweetened cocoa, beer, olives, and citrus peel, which contain different kinds of complex organic compounds rather than simply metal ions.
As for the other tastes, sour is triggered by acids (by increasing H+ concentration), sweet is primarily triggered by sugars and some artificial sweeteners, and umami taste is elicited by amino acids such as glutamate and aspartate which are found in high-protein foods like fish, shellfish, cured meats, mushrooms, and cheese.