Characterization of dark chocolates based on polyphenolic profiles and antioxidant activity

Area of Science:

• Food Chemistry
• Analytical Chemistry
• Agricultural Science

Background:

• Dark chocolate quality is influenced by geographical origin and cocoa variety.
• Detecting fraud and ensuring authenticity requires reliable analytical markers.
• Methylxanthine and polyphenolic profiles, along with antioxidant activity, are key indicators.

Purpose of the Study:

• To characterize dark chocolates based on origin, variety, and content.
• To identify potential markers for quality, variety, and origin.
• To address issues related to authentication and fraud detection in dark chocolate.

Main Methods:

• Analyzed 26 dark chocolates from Africa, America, and Asia, including Criollo, Forastero, and Trinitario varieties.
• Optimized sample preparation involved defatting and methanol/water extraction via sonication.
• Utilized reversed-phase high-performance liquid chromatography (RP-HPLC) with UV and spectrophotometric methods (Folin-Ciocalteu, FRAP, aluminum assays).

Main Results:

• American dark chocolates exhibited higher alkaloid and phenolic content compared to African samples (e.g., 1.7 vs. 1.1 mg g⁻¹ caffeine).
• Criollo cocoa varieties demonstrated superior bioactive compounds and antioxidant capacity (e.g., 16 mg g⁻¹ total flavanols).
• Specific analytes were identified as potential descriptors for varietal and geographical attributes.

Conclusions:

• The methylxanthine and polyphenolic composition, along with antioxidant activity, can serve as markers for dark chocolate authentication.
• Geographical origin and cocoa variety significantly impact the chemical composition and quality of dark chocolate.
• This analytical approach provides a basis for identifying quality, variety, and origin, crucial for combating food fraud.