CHAPTER 27: Trigonelline and Derivatives

Trigonelline is a water-soluble alkaloid derived in plants from the enzymatic methylation of the pyridine nucleotide of nicotinic acid by trigonelline synthase. The content of trigonelline in coffee seeds may be influenced by various intrinsic and extrinsic factors and, given the thermo-labile nature of trigonelline, losses of 50–90% of its original content may occur during roasting. The concentrations of trigonelline and derivatives vary with brewing method as for other soluble compounds. The alkaloid seems to impart bitterness to coffee brew and their derivative compounds formed during roasting, such as pyridines and pyrroles, contribute to the global coffee aroma and flavor. During roasting, trigonelline demethylation results in nicotinic acid, a form of niacin or vitamin B₃. In humans, this vitamin participates in various metabolic processes. Additional pyridine derivatives such as N-methylpyridinium linked to potential health effects are also produced during roasting. These aspects will be approached in this chapter.