Moisture Content and Bean Weight Dynamics of the Parchment Arabica Coffee (Coffea arabica L.) Varieties During Sun Drying

Abstract

Coffee post-harvest quality is highly dependent on drying, with sun drying being prevalent among smallholders. This method, however, is influenced by environmental factors and intrinsic bean properties. This study evaluated the moisture content and bean weight dynamics on parchment bean of six Arabica coffee varieties, namely Gayo 1, Gayo 2, K130, K29, S795, Sigarar Utang during
natural sun drying in East Java, Indonesia. Beans were dried to a stable storage moisture, with periodic measurements of weight per fixed volume and gravimetric moisture content. Results showed that the drying follows a non-linear quadratic pattern (R² 0.98–0.991), characterized by an initial rapid loss phase followed by a slower, diffusion-controlled phase. Significant varietal differences were observed in drying kinetics. Sigarar Utang dried fastest, reaching <12% moisture in 11–12 days, while other varieties required 15 days. Bean weight reduction was strongly correlated with moisture losses, providing a practical monitoring indicator. The findings
conclude that drying behavior is variety-specific, influenced by bean morphology and parchment layer characteristics. Therefore, optimizing post-harvest practices requires consideration of these varietal traits to enhance efficiency, prevent overdrying, and maintain bean quality.