Effect of Roasting and Alkalization on the Chemical Composition and In Vitro Anti-Inflammatory Effects of Cocoa

Abstract

Abstract Objectives Cocoa beans undergo fermentation, roasting, and possibly alkalization prior to consumption. Cocoa and chocolate have been shown to exert anti-inflammatory effects. Previous studies have shown that roasting and alkalization can adversely affect the total phenolic content (TPC) of cocoa, but the effect of these steps on bioactivity has not been well-studied. Our objective was to prepare cocoa powders using different roasting and alkalization protocols and measure their chemical composition and in vitro anti-inflammatory activity. Methods Cocoa beans were roasted (110–150°C) and alkali-treated (0 – 120 min) using a 22 + center point study design. Cocoa nibs were defatted and extracted with 70% aqueous acetone. The extract was dried prior to analysis. TPC was determined using the Folin-Ciocalteu method. Select polyphenols were quantified by liquid chromatography. In vitro anti-inflammatory activity was assessed as inhibition of phospholipase A2 (PLA2) and inhibition of interleukin 8 (IL8) production by tumor necrosis factor a-stimulated HT-29 human colon cells. Results Roasting and alkalization led to decreased TPC, but alkalization had a greater effect. Cocoa beans roasted at 130°C and alkalized for 120 min had 44% lower TPC than those roasted that same way but without alkalization. In the absence of alkalization, beans roasted at 150°C had only a 13% lower TPC than beans roasted at 110°C. Roasting and alkalization also influenced the levels of individual polyphenols, but the effects varied based on the analyte of interest. Roasting tended to enhance the PLA2, inhibitory potency of the cocoa whereas alkalization reduced inhibitory potency. Cocoa that had been roasted at 150°C but not alkalized had the lowest IC50 (14 mg/mL) whereas cocoa that had been roasted at 150°C and alkalized for 120 min had the highest (>100 mg/mL). Similar results were observed for inhibition of IL8 production. Conclusions Roasting and alkalization are important for achieving desired sensory characteristics in cocoa, but these processes adversely affect the levels of polyphenols in cocoa and has been considered inconsistent with maintaining bioactivity. Our results suggest that it is possible to identify processing protocols that balance the sensory characteristics of cocoa with its anti-inflammatory activity. Funding Sources This work was funded by USDA AFRI.