Impact of roasting and storage conditions on the shelf stability of Thai Arabica coffee

Abstract

This research investigated the impact of roasting levels and storage conditions on coffee quality by analyzing moisture content (MC), color, peroxide value (PV), shelf-life, and volatile compounds using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GCMS). Coffee samples were collected from Doi Chang, Thailand, and processed using natural/dry, washed/wet, and honey methods. The samples were then roasted to light at 205 °C, light-medium at 210 °C, and medium at 218 °C. The roasted coffee beans were packaged in hermetic bags and subjected to accelerated storage conditions for 0, 7, 14, and 21 days at 30, 40, and 50 °C with 50 % RH. Results showed that roasting level and accelerated storage significantly affected (p < 0.05) MC, color, PV, shelf-life, and volatile compound profiles. Eighty-two volatile compounds were identified across the light, light-medium and medium samples. The dominant compound groups were furans (ranging from 35 ± 6 to 54 ± 3 % d.w.) pyrazines (13 ± 1 to 32.3 ± 0.8 % d.w.), and esters (4.2 ± 0.2 to 16.7 ± 0.9 % d.w.), which contribute significantly to coffee aroma. Shelf-life at 30 °C was longest for light (10.0 ± 0.1 to 11.7 ± 0.3 days), followed by light-medium (7.3 ± 0.3 to 8.8 ± 0.6 days) and medium (6.3 ± 0.3 to 7.7 ± 0.6 days), compared to storage at 40 and 50 °C. The concentrations of volatile compounds including alcohols, aldehydes, esters, furans, furanones, ketones, organic acids, pyrazines, pyridines, pyrroles, sulfides, and terpenes were influenced by roasting level, processing method, and storage conditions, ultimately affecting coffee shelf-life.