Loss of Native Flavanols during Fermentation and Roasting Does Not Necessarily Reduce Digestive Enzyme-Inhibiting Bioactivities of Cocoa

Abstract

Polyphenol profiles and in vitro digestive enzyme inhibitory activities were compared between cocoa extracts from unfermented beans (UB), fermented beans (FB), unfermented liquor (UL), and fermented liquor (FL). Total polyphenols, total flavanols, and individual flavanols were significantly different between UB/FB and UL/FL. All extracts effectively inhibited α-glucosidase (lowest IC50 = 90.0 μg/mL, UL) and moderately inhibited α-amylase (lowest IC50 = 183 μg/mL, FL) and lipase (lowest IC25 = 65.5 μg/mL, FB). Our data suggest that fermentation does not reduce α-glucosidase inhibition, while roasting may enhance inhibition. For α-amylase, both fermentation and roasting improved inhibition. Finally, for lipase, both fermentation and roasting attenuated inhibition. Conclusive correlations between inhibition and mDP, total polyphenol, and flavanol contents were not found. Our data suggest that enzyme inhibition activities of cocoa are not uniformly reduced by polyphenol/flavanol losses during fermentation and roasting. This paradigm-challenging finding suggests other cocoa constituents, potentially formed during processing, contribute to digestive enzyme inhibition.

Correlation between Antimicrobial, Antioxidant Activity, and Polyphenols of Alkalized/Nonalkalized Cocoa Powders

“…Our reported data suggest that distinct activities of cocoa powder are not consistently reduced by phenol losses as a result of alkalization process. A similar observation was reported by Ryan and others (), who demonstrated that the loss of native flavanols during cocoa roasting and fermentation is not necessarily connected with the reduction in the digestive enzymes inhibition. A potential explanation for these observations is the formation of new bioactive compounds during alkalization that have prominent antimicrobial but not antioxidant activity.…”

Flavanol Polymerization Is a Superior Predictor of α-Glucosidase Inhibitory Activity Compared to Flavanol or Total Polyphenol Concentrations in Cocoas Prepared by Variations in Controlled Fermentation and Roasting of the Same Raw Cocoa Beans

“…Polyphenol-rich extracts were made from raw beans, the fermented cocoa beans, and powders for all seven treatments, as described previously [13,30]. The Folin-Ciocalteu colorimetric assay was used to approximate the total phenolic content of the freeze-dried cocoa extracts, and total flavanols were measured by the 4-dimethylaminocinnamaldehyde (DMAC) colorimetric assay, as previously described in Dorenkott et al [12].…”

“…as potential inhibitors [16]. While isolated PCs are effective α-glucosidase inhibitors, we recently found that various cocoas were effective inhibitors of α-glucosidase, despite large reductions in native flavanols as a result of fermentation and roasting [13]. These results challenge the idea that losses of native flavanols inherently reduces all bioactivity of cocoa and, therefore, warrant further investigation into the factors that determine α-glucosidase inhibition.…”

“…The widely-accepted paradigm is that preservation of native flavanols is critical for retaining bioactivity [7,9,11]. However, it is possible that reactions occurring throughout processing may generate processing-derived compounds with novel activities, such as lignin-like complexes and melanoidins, potentially preserving or even enhancing certain bioactivities as compared to the raw cocoa bean [7,[12][13][14][15][16][17][18][19]. The levels and activities of these large, complex, and diverse compounds in cocoa are largely unknown due to analytical challenges (such as lack of authentic standards, structural complexity and size of potential products), low bioavailability of large complex compounds, and the continued research focus on small monomeric flavanols.In vivo, flavanols have highly variable systemic oral bioavailability, with absorption being inversely proportional to molecular weight and~0% absorption for compounds ≥ tetramer [20][21][22][23][24].…”

“…Specifically, the inhibition of gut digestive enzymes to limit macronutrient digestion is a promising mode of bioactivity that does not require systemic bioavailability. Previous studies demonstrate that cocoa flavanols inhibit lipases, α-amylase, and α-glucosidase; α-glucosidase appears to be the most susceptible to cocoa inhibition [13,25]. α-glucosidase is a brush border enzyme that hydrolyzes starch and maltose into absorbable glucose [26].…”