Trigonelline |
In coffee, trigonelline is an slightly bitter alkaloid and important precursor for various flavor compounds. Concentrations of trigonelline are higher for arabica than robusta and ranging from 0.6-1.3% and 0.3-0.9%, respectively1. During roasting trigonelline partially degrades to produce two important compounds - pyridines and nicotinic acid - such that a very dark roast contain only a fraction of its original trigonelline content. Roasting results in a loss of 50-80% its initial concentration with a large portion being conveted into pyridine. As such, these heterocyclic compounds have been found to impart roasty coffee aromas in the beverage. The second decompositon product produced is nicotinic acid or also known was vitamin B3 (niacin). Nicotinic acid is produced by demethylation of trigonelline and its formation becomes significant at temperatures above 160oC - at 230oC nearly 85% is decomposed. Roasting experiments have shown that nicotinic acid formation depend more on roasting temperature than on duration of roast. Depending on roasting conditions, niacin levels can increase up to ten times its initial concentration5. Interestingly, coffee has been documented as an ample source of niacin providing 10-40mg of niacin per 100g of coffee far exceeding the daily recommended dose of 18/mg1 - espresso coffee provides 2-3mg/cup. In decaffeinated coffee, nicotinic acid concentrations are usually lower (35%) due to the elimination of trigonelline by chlorinated solvents. Trigonelline has recently been found to reduce dental caries due to its ability to prevent Stretococcal mutans from adhering to teeth enamel. References: |
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