Comparative effects of superheated steam and hot air roasting on the in vitro phospholipase A₂ inhibitory activity and polyphenol composition of cocoa beans

Background: Cocoa, derived from Theobroma cacao, is a popular food ingredient used to produce chocolate. Cocoa is rich in polyphenols and human and laboratory model studies have indicated that cocoa and chocolate can mitigate chronic inflammatory conditions. Cocoa is subjected to post-harvest processing operations including fermentation and roasting prior to use. These steps, which are essential for flavor development, have been shown to lead to changes in the content and profile of polyphenols in cocoa. Less is known about the effect of these operations on the bioactivity of cocoa. The present study compared the impact of using superheated steam (SHS) versus hot air (HA) as a roasting medium for cocoa beans on in vitro phospholipase A₂ (PLA₂) inhibitory activity, a surrogate for anti-inflammatory activity, and polyphenol chemistry. Results: Beans were roasted at 150 °C (10, 20, 30 min), 175 °C (8, 15 min) and 200 °C (7 min) using SHS or HA. The median inhibitory concentration (IC₅₀) against PLA₂ of extracts from SHS beans at 175 °C was 50% lower than comparable HA beans. Although total phenolic content in HA beans for all roasting treatments was 20% to 33% higher than SHS beans, the levels of proanthocyanidin (PAC) tetramer and pentamer in beans roasted at 175 °C for 8 min were 23% and 36% higher, respectively, than those roasted using HA. Conclusions: The findings of this study suggest that SHS roasting could be used to produce beans with greater anti-inflammatory activity and higher levels of key PACs in comparison with HA.