Effect of sun and convective drying under different temperature–time conditions on the physicochemical and bioactive properties of Mexican Forastero cocoa beans (Theobroma cacao L.)

Drying is a vital postharvest stage in cocoa processing because it reduces moisture content and affects the physicochemical and bioactive properties of the beans. This study evaluated the effects of traditional sun drying and controlled convective drying under different temperature–time regimes on fermented Mexican Forastero cocoa beans from Chiapas, Mexico. Beans that had been fermented for 168 hr were either sun-dried (STS) or convectively dried at 35, 40, 45 and 50 °C (SC-35–SC-50). We measured proximate composition, Commission Internationale de l'Éclairage L*a*b* (CIELAB) colour parameters, total polyphenol content (TPC) and antioxidant capacity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays. Pearson correlations were used to examine the associations between the drying conditions and the bioactive responses. All treatments reduced moisture content to less than 7 %, but drying time decreased from 56 hr for STS to 14 hr for SC-50. Several physicochemical, colour and bioactive properties were significantly influenced by the drying conditions. SC-50 caused the most marked darkening and had the lowest TPC and antioxidant activity. SC-35 and SC-45 had the highest TPC and DPPH radical-scavenging activity. Total polyphenol content was strongly correlated with DPPH (r = 0.906), while drying temperature and time were strongly inversely correlated (r = -0.944), showing that both factors should be considered together. These findings support the development of standardised drying criteria based on temperature–time conditions, final moisture content and relevant quality attributes in order to obtain more consistent Mexican Forastero cocoa beans for further processing.