Improvement of Robusta coffee aroma with L-leucine powder.

BACKGROUND L-leucine powder (LP) was added to green Robusta coffee beans for reducing the difference in flavor between Robusta and Arabica coffee. L-leucine was selected as an additive based on the Maillard reaction. The pre-treatment method conducted in this study was a short soaking (M1) or spraying procedure (M2), then LP was added at varying levels up to 3% (w/w, 30 g/kg). All samples were roasted (240 °C/15 min) and extracted using an espresso machine. Volatile compounds were analysed by solid-phase microextraction-gas chromatography-mass selective detection. RESULTS Thirty volatile compounds (6 pyrroles, 8 pyrazines, 3 phenols, 9 furans, 2 ketones, 2 aldehydes) were analysed. In 15 coffee samples, the levels of total volatile compounds (based on peak area ratios) ranged from 8.9 (M1-1) to 15. NTR had higher levels of bitter aroma compounds than Arabica coffee, and Robusta coffee had lower levels of bitter aroma compounds when pre-treated with LP. The sum of bitter volatiles (phenols, pyrroles, pyrazines) was lowest in M1-5 (3% LP), M2-1 (1% LP; both dried at 50 °C/15 min) and M2-7 (3% LP, dried at 70 °C/15 min) compared with NTR (p < 0.05). CONCLUSION As a results of this study, pre-treatment with LP can improve the flavor of Robusta. This article is protected by copyright. All rights reserved.

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