Effect of different conching processes on procyanidin content and antioxidant properties of chocolate

• The effect of conching on bioactive content and activity in chocolate was studied.
• Two processes characterized by different t/T combinations were investigated.
• Procyanidin content and pattern were affected by the different processing conditions.
• The water-soluble extracts showed a lower antioxidant activity than procyanidins.
• No further development of Maillard reaction occurred during conching.

The effect of two conching processes, namely Long Time Conching (LTC) and Short Time Conching (STC), on the content of bioactive compounds and on their activity in chocolate was investigated. The dark chocolates so produced were extracted with both organic solvent and water to investigate the content and different contribution of procyanidins, water-soluble phenolic and melanoidin fractions to the overall antioxidant activity. The procyanidin content and pattern were deeply affected by the different processing conditions: after conching the STC-samples presented a higher amount of monomers compared to the LTC-ones which, in turn, resulted more polymerized as confirmed by the presence of P10 polymers.Both STC- and LTC-products presented comparable phenolic content and FRAP values but products collected at the different conching steps, and in particular during LTC, showed a significant improvement of the radical scavenging properties (TEACPROC). The aqueous extract showed a lower antioxidant activity compared to TEACPROC. Based on the analysis of the melanoidin fraction, no further development of Maillard reaction occurred as a consequence of conching.