Temperature-Dependent Changes in Physicochemical Properties and Selected Bioactive Compounds During Controlled Fermentation of Cocoa Beans (Theobroma cacao)

Cocoa bean (Theobroma cacao L.) fermentation is an important postharvest process that influences the physicochemical characteristics and quality of cocoa beans. This study investigated the effects of controlled fermentation temperatures (15, 25, 35, and 45 °C) on physicochemical properties and metabolite dynamics. Beans were fermented for 8 days without turning during the first 2 days, followed by daily turning and drying at 50 °C for 3 days. Fermentation temperature significantly affected physicochemical properties, metabolite profiles, and quality-related characteristics of dried cocoa beans. Fermentation at 15 °C showed characteristics of less extensive fermentation, including the highest yield (47.17%), water activity (0.57), reducing sugar (17.84 mg/g), and total phenolic compounds (2.39 mg/g), together with the lowest total titratable acidity (0.26%). In contrast, fermentation at 45 °C resulted in the lowest yield (37.67%), total soluble solids (2.23 °Brix), moisture content (4.11%), water activity (0.46), reducing sugar (3.24 mg/g), and total phenolic compounds (0.36 mg/g), while producing the highest total titratable acidity (0.39%). Theobromine content remained unchanged (3.38–3.87 mg/g), whereas catechin increased slightly (0.03–0.10 mg/g) with increasing temperature. These findings support temperature-controlled fermentation for improving postharvest quality control and value addition in cocoa production.