Previous work in model systems has demonstrated that mepiquat can be formed under typical roasting conditions from the amino acid lysine via the Maillard reaction and trigonelline, the latter alkaloid serving as a methyl donor. This study shows for the first time that mepiquat is formed in low mg kg(-1) amounts during the coffee roasting process and consequently can be detected in roast and ground as well as soluble coffee up to levels of 1.4 mg kg(-1). Darker roast coffees contain relatively higher amounts of mepiquat versus light roasted beans, with an excellent correlation of mepiquat formation to roast colour (r(2) = 0.99) in robusta beans. A survey of 20 of the major green coffee origins (robusta and arabica coffees) showed the absence of mepiquat (<0.005 mg kg(-1)). Preliminary studies indicate that mepiquat is not formed during processing (thermal treatment) in most of the cereal-based foods such as pizza and ready-to-eat cereals, but was detected in barley after roasting (0.64 mg kg(-1)). Mepiquat can therefore be considered a process-induced compound formed from natural constituents during the roasting process. Even considering a high intake of seven cups per day of soluble coffee containing 1.4 mg kg(-1) mepiquat in the coffee powder (the highest amount measured in this study), the resulting intake would exhaust less than 0.2% of the ADI of mepiquat.

Mepiquat, a growth regulator widely used in agriculture, is also known as a process-induced byproduct formed in coffee from natural constituents during heat treatments such as roasting. This study examines mepiquat formation in cereal-based foodstuffs treated at sufficiently high temperature to trigger methyl transfer reactions that involve glycine betaine and choline naturally present in cereals. Color measurements of roasted barley grains revealed a correlation between thermal treatment and mepiquat content. Trials at industrial scale on instant beverages composed of roasted cereals demonstrated significant increases in mepiquat during the thermal process (in the range of 140-205 μg/kg in final products). A targeted survey of commercial products showed mepiquat in the range 69-381 μg/kg in powdered cereal instant drinks and 42-168 μg/kg in mugicha tea, a roasted barley infusion. These findings will not significantly affect the exposure of consumers to mepiquat due to the low amounts detected.