| RQ | Facet | Categories | Multiple/single |
| 1 | Research type | Validation research, evaluation research, solution proposal, philosophical papers, opinion papers, experience papers, review papers | Single | 2 | Quality metric | Bean quality, cup quality, food safety, biochemical composition, soil quality, quality perception, crop yield, microbiological composition, physicochemical properties, crop quality | Multiple | 3 | Quality objective | Improve quality, measure quality, quality correlation, quality discrimination | Multiple | 4 | Technique | Sensory evaluation, physical evaluation, analytical chemistry methods, modeling, microbiological analysis, molecular biology methods, new technologies | Multiple | 5 | Coffee species | Coffea arabica, Coffea canephora, Coffea liberica, coffee, hybrids, blended coffee, not declared | Multiple | 6 | Coffee sample | Green coffee, roasted coffee, instant coffee, brewed coffee, cherry coffee, coffee plant | Multiple | 7 | Process’ stage | Pre-harvest stage, post-harvest stage, brewing stage | Multiple | 7 | Pre-harvest stage | Soil conditions, coffee origin, environmental conditions, crop altitude, shade, genetic traits, coffee breeding, management practices, fruit development | Multiple | 7 | Post-harvest stage | Harvest, processing, Drying, sorting, pretreatment and additives, storage, packaging, roasting, grinding, brewing, quality control | Multiple |
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