Microstructural characterization and evaluation of the physical and chemical quality of specialty roasted Coffea arabica L. with Pluma designation of origin

Abstract

The state of Oaxaca, Mexico obtained the designation of origin “Pluma.” Roasting is one of the stages contributing to the coffee bean’s physical, chemical, and sensory quality. Therefore, this study aimed to analyze the microstructure, physical parameters, and chemical composition in special grains of Coffea arabica L. with designation of origin “Pluma.” Scanning electron microscopy (SEM) and dispersive X-ray spectroscopy (EDX) analysis provided elemental analysis and chemical composition of coffee beans’ external surface and internal macrostructure, respectively. Therefore, the nitrogen concentration in coffee beans was PLU 8.65%, AGL 10.06%, TEO 12.01%, MAP 13.26, and PTO 15.04%. In addition, trace elements of tellurium, iodine, calcium, and titanium were identified in the coffee bean samples. The porosity by Imagine J and the physical analysis were carried out according to regulations. The C. arabica L. beans from MAP and HUA are the roughest and both are located at a lower altitude than the rest. The quantification of total polyphenols is higher for coffee beans of PLU with 56.04 and AGL with 56.72 mg EAG g-1 bs and the antioxidant capacity was PLU 320.54 and AGL 330.10 µmol Eq. Trolox g-1 bs, these values correspond to coffee beans grown at higher altitudes from 1343 to 1820 masl, respectively. The total polyphenol content and antioxidant capacity increased in coffee beans as the altitude at which they were grown increased. The control sample showed similar characteristics in terms of the attributes analyzed. C (66.48–81.14%) and O (18.86–28.69%) were found on the outside of all grains, except in AGL where Ca (4.5%) was detected, which can be a discriminating element to determine its authenticity.