Comparative Characterization and Valorization Potential of Cupuaçu (Theobroma grandiflorum) and Cocoa (Theobroma cacao) Peels: Physicochemical, Proximate, Phenolic, and Antioxidant Properties

The peels of cupuaçu (Theobroma grandiflorum) and cocoa (Theobroma cacao), generated in large quantities by the food agroindustry in Pará, are sources of valuable biomolecules, particularly phenolic compounds with antioxidant potential. The physicochemical and proximate composition characterization of these matrices allows their composition, quality, and technological potential to be assessed, considering parameters such as pH, titratable acidity, soluble solids, moisture, ash, lipids, proteins, and carbohydrates. Therefore, this study evaluated the physicochemical parameters, proximate composition, and total phenolic compounds of cupuaçu and cocoa peels, aiming to characterize and identify their potential for industrial and biotechnological applications.

The peels were obtained from local processing units in the Metropolitan Region of Belém, Pará, Brazil. After sanitization with sodium hypochlorite (50 ppm/15 min), the samples were dried at 50 °C, ground (≤1 mm), vacuum-packed, and stored at −20 °C. Proximate and physicochemical characterization followed official AOAC methods for moisture, ash, lipids, proteins, carbohydrates, titratable acidity, and total soluble solids, performed in triplicate using gravimetric, titrimetric, spectrophotometric, and refractometric techniques.

Soluble phenolic compounds were extracted by adapting the protocol of Arruda et al. (2018), using methanol, acetone, and water (7:7:6, v/v/v) in an ultrasonic bath. After centrifugation and successive re-extractions, the supernatants were combined, concentrated using a rotary evaporator, and made up to volume to obtain the Soluble Extract (SE). In this extract, total phenolics, flavonoids, and condensed tannins were quantified using colorimetric methods, while in vitro antioxidant capacity was evaluated using the FRAP and ABTS assays.

The cupuaçu peel (CP) presented higher carbohydrate (43.41±0,48%), ash (2.03±0%), and titratable acidity (4.02±0,66%) contents, as well as a higher concentration of total phenolic compounds (8.94 mg/g±0,15), where this profile favors its use as a substrate in fermentation and biotransformation processes. In contrast, cocoa peel (CC) presented higher protein (7.10±1,08%), lipid (1.16±0,10%), flavonoid (17.38±0,63 mg/g), and tannin (12.67±0,62 mg/g) contents, as well as greater antioxidant capacity according to FRAP (16.93±0,06 µmol Trolox/g) and ABTS (194.88±0,67 µmol Trolox/g), indicating potential for the production of bioactive compounds and functional ingredients.

CP appears more promising as a substrate for fermentation processes due to its higher carbohydrate content and acidity, whereas CC stands out as a source of bioactive compounds, presenting higher levels of flavonoids, tannins, and antioxidant capacity, in addition to higher protein content, which expands its potential for functional and biotechnological applications. Thus, each matrix presents a distinct potential within an integrated valorization chain.

Cupuaçu and cocoa peels demonstrate potential for exploitation through valorization and biorefinery strategies, directing their different components toward higher-value applications. Both can be used as substrates and bioinputs for fermentation processes, the production of bioactive compounds, and the development of antioxidant extracts and functional ingredients.

Acknowledgments: CNPq, grant number 444295/2024–0.