Sulfur aroma compounds in gum Arabic/maltodextrin microparticles

Abstract

The sulfur compounds 2-furfurylthiol (2FFT), dimethyl disulfide (DMDS) and thiophene (THIO) are important sulfur contributors to roasted coffee aromas. Their loss by evaporation and/or degradation directly impacts the freshness and aroma intensity of coffee brews. To improve their stability, 2FFT, DMDS and THIO were microencapsulated by spray drying in Gum arabic (GA) and maltodextrin (MD). A CG-qMS method was developed and validated to accurately quantify the sulfur compounds as well as their microencapsulation process and storage stability. Selectivity was obtained by CG-SIM-qMS despite an observed matrix effect. The calibration curves were linear over the tested range. The LOQ for 2FFT, THIO and DMDS were 10, 15 and 23 μg mL−1, respectively, and the corresponding LOD were 3, 5 and 7 μg mL−1. Repeatability, reproducibility and recoveries were obtained within acceptable levels. Microparticles production was tested at different inlet temperatures, and the best encapsulation efficiency was found to be 67% for 2FFT, at 140 °C. The microcapsules were characterized in terms of moisture content, hygroscopicity, solubility, surface morphology, particle size distribution and X-ray diffraction characteristic. A fifteen-week storage stability study at −18 °C indicated that GA and MD offered good protection for the sulfur aromas, especially for THIO and DMDS.