Effects of Fermentation Temperature on the Physicochemical Properties, Bioactive Compounds, and In Vitro Digestive Profile of Cacao (Theobroma cacao) Seeds

This study investigates the impact of fermentation temperature on the physicochemical properties, bioactive compound retention, and in vitro digestion profile of cacao seeds (Theobroma cacao L.). Three fermentation conditions were evaluated: low (F40, 40 °C), medium (Control, 50 °C), and high (F60, 60 °C). The study assessed macronutrient composition, phenolic compound retention, antioxidant activity, enzymatic activity, structural changes, and glucose release during in vitro digestion. Fermentation temperature significantly influenced cacao seed quality and functionality. F40 preserved the highest levels of phenolic compounds (61% reduction compared to raw seeds) and antioxidant activity (73% reduction), offering a pronounced hypoglycemic effect through enzyme inhibition. In contrast, F60 facilitated extensive enzymatic activity, particularly protease and lipase, promoting flavor precursor formation and structural changes like cracking. However, this high-temperature treatment resulted in significant losses of phenolic compounds (76%) and antioxidant capacity (88%). Structural analysis revealed that higher fermentation temperatures enhanced cellular breakdown, increasing enzymatic access and glucose bioavailability. Digestion studies confirmed that roasted cacao fermented at higher temperatures released more glucose, driven by enzymatic hydrolysis and structural modifications. Conversely, the cacao from F40 exhibited slower glucose release due to the retention of bioactive compounds that inhibit carbohydrate-hydrolyzing enzymes. This research underscores the trade-offs in cacao processing: fermentation temperature significantly modulates cacao seed properties. At higher temperatures (60 °C), enhanced enzymatic activity (protease, lipase) facilitates the release of flavor precursors and structural modifications, increasing digestibility and glucose bioavailability, making it ideal for chocolate production. Conversely, fermentation at lower temperatures (40 °C) preserves bioactive compounds, including phenolics and antioxidants (with 61% retention compared to raw seeds), which may offer functional food applications for glycemic control. Roasting reversed some fermentation effects, reducing phenolic retention while increasing glucose bioavailability. This work tailors cacao fermentation for diverse end uses, from premium chocolate to nutraceutical products aimed at glycemic control.