Unveiling the cocoa-carob flavour gap in dark chocolates via instrumental and descriptive sensory analyses

Roasted carob pulp (Ceratonia siliqua) is a cocoa substitute known for its faint cocoa-like resemblance. However, the cocoa-carob flavour gap remains poorly uncharacterised. This study aimed to elucidate the sensory and molecular aspects of this flavour gap in a 70 % dark chocolate formulation via a two-pronged instrumental-sensorial approach. Descriptive Sensory Analysis (DSA) revealed carob-based chocolate was significantly sweeter, less sour and astringent than conventional dark chocolate due to the high total sugar content (45-50 % DM; HPLC/RID), low titratable acidity and tannin content, respectively. As for aroma, a distinct, albeit weak, cocoa-like aroma was present in carob-based chocolate. HS-SPME-GC-MS/FID revealed this was attributed to branched-chain Strecker aldehyde generation during roasting (2-methylbutanal, 1.17 μg/g; 3-methylbutanal, 2.89 μg/g). Notably, there was a distinct lack of alkylpyrazines. Additionally, a distinct woody, tree bark-like odour was uniquely associated with carob-based chocolates. This was due to furfural generation during roasting (2.33 μg/g). In conclusion, the aroma and taste gap between cocoa and carob was successfully characterised in this study. These findings substantiate the potential of carob application in chocolate manufacturing, thus empowering confectioners to make evidence-based decisions when evaluating cocoa substitutes.