Roasting cocoa beans can help preserve health benefits, study shows

06 Apr 2018 --- Manipulating the temperature and the period of roasting can preserve and even boost the potency of some bioactive and antioxidant compounds of cocoa, while protecting desired sensory aspects of chocolate, according to Penn State researchers. Previous research has suggested that roasting always results in a reduction in polyphenol content in beans. Cocoa polyphenols are believed to have a positive influence on human health, especially with regard to cardiovascular and inflammatory diseases, metabolic disorders and cancer prevention.

Chocolate, a food usually consumed for pleasure, in recent years has been reconsidered as a source of healthy compounds, notes lead researcher Joshua Lambert, associate professor of food science. 

The goal of the study, he explains, was to learn whether the roasting of cocoa beans could both preserve preferred flavor characteristics and boost health benefits.

NutritionInsight has recently engaged with the healthier sides of indulgent products, including chocolate and its age-old health benefits. 

The study investigated the impact of whole-bean roasting on the polyphenol content, aroma-related chemistry and pancreatic lipase inhibitory activity of cocoa under a range of roasting conditions. The inhibition of pancreatic lipase activity is a potential anti-obesity strategy.

In the study, total phenolics, epicatechin, and smaller proanthocyanidins were reduced by roasting at temperatures under 302 degrees Fahrenheit, Lambert pointed out. By contrast, roasting at 302F or above increased the levels of catechin and larger proanthocyanidins, which have a greater ability to inhibit pancreas lipase.

Consistent with these changes, researchers found that cocoa roasted at 338 F better inhibited pancreatic lipase inhibitory activity than cocoa roasted at lower temperatures. Cocoa aroma-related compounds increased with roasting above 212 F, whereas deleterious sensory-related compounds formed at more severe temperatures, 338 F.

The research findings suggest that cocoa roasting can be optimized to increase the content of some polyphenols and boost anti-pancreas-lipase activity, while maintaining a favorable aroma profile, Lambert points out.

“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,” he says. “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.”

The findings of the research, which were recently published on-line in Food Chemistry, will be of interest to chocolate makers, Lambert believes, because of an increasing demand for chocolate products offering enhanced health benefits. He cited as an example Mars company's CocoaVia cocoa-extract supplement that promises to deliver 375 mg of cocoa flavanols -- antioxidants -- in each serving to promote good health.CasaLuker also produces a product that markets itself as cocoa with extreme health benefits such as antioxidants and fiber. 

“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," Lambert says. “We need to know how processing really affects the biological activity rather than to make an assumption that processing is always bad and that unprocessed or minimally-processed foods are always more healthful.”