Roasting cocoa beans preserves health benefits and taste

Penn State University researchers have found that manipulating the temperature and time in the roasting process of cocoa beans can provide a boost to the potency of its bioactive and antioxidant properties while delivering the same sensory aspects of chocolate.

Chocolate has been reconsidered recently as a source of healthy compounds, according to lead author and Penn State associate professor of food science Dr Joshua Lambert. The aim of the study was to develop a better technique for roasting cocoa beans that preserves both the flavour and health benefits of chocolate.

The findings contradict traditional studies that suggest roasting cocoa beans always leads to a reduction in their polyphenol content. Cocoa polyphenols are beneficial to human health with regards to cardiovascular and inflammatory diseases, metabolic disorders, and in the prevention of cancers.

The teams evaluated the impact of whole-bean roasting, observing the polyphenol content, aroma-related chemistry and pancreatic lipase inhibitory activity under a variety of different temperatures and timescales.

Pancreatic lipase is the enzyme that breaks down triglycerides into fatty acids for absorption into the small intestine. An inhibitor impedes the formation of fatty acids, thus preventing absorption of dietary fats into the body.

The study found that when roasting cocoa beans at less than 302°F (150°C), the total number of phenolics, epicatechin and smaller proanthocyanidins is reduced. Dr Lambert pointed out that roasting beans at 302°F or higher increased the levels of catechin and larger proanthocyanidins, leading to a stronger inhibition of pancreatic lipase.

Cocoa beans roasted at 338°F (170°C) better inhibited pancreatic lipase activity than at lower temperatures. Cocoa-aroma related compounds performance were maximised at above 212°F (100°C), but these flavour properties were reduced at a higher temperature of 338°F.

“Our results show that if you look at the individual polyphenolic content or the individual polyphenol compounds in cocoa, roasting causes some of them to go down while some of them go up. It is more complicated than saying that roasting leads to a decrease in phenolic content, and that by extension roasting reduces the health beneficial effects of cocoa,” said Dr Lambert.

“The effects of roasting and processing are complex and it’s important to better understand what’s going on in terms of the effect of the processing on the chemistry of the food.”

He suggested these findings would be of specific interest to chocolate manufacturers responding to a demand for healthier chocolate, citing Mars’s CocoaVia range, which promises to deliver 375mg of cocoa flavanol antioxidants per serving.

He told Food Processing Technology: “We did find that under certain roasting conditions, the levels of higher molecular weight proanthocyanidins (HmwPACs), which we think are important for health-related activity, increased.”

“Future studies need to determine the health effects of these cocoas in models of human disease and to evaluate the consumer acceptability of the cocoas as part of a chocolate product.”