Intense Roasting of Cocoa Beans Reduces Bitterness: New Study

Confectioners who want to create products with 100% chocolate and no sugar for health-conscious consumers can reduce bitterness and improve flavour acceptance by roasting cocoa beans for longer and at higher temperatures.

That's the conclusion of a new study conducted by a team of researchers at Penn State's Sensory Evaluation Center in the Department of Food Science. The study included 27 100 percent chocolate preparations made from cocoa beans roasted at various intensities, as well as 145 people who came to the centre on five consecutive days to evaluate five different samples.

Findings of Study:

According to research team member Helene Hopfer, Rasmussen Career Development Professor in Food Science in the College of Agricultural Sciences, the study confirmed that bitterness and astringency are negatively correlated with consumer liking and demonstrated that those qualities in chocolate can be reduced by optimizing roasting.

"More and more people these days are eating darker chocolates with less sugar and more cacao because they are trying to reduce their sugar intake or they want to take advantage of perceived health benefits," she explained. "Dark chocolate contains a high concentration of flavonoids, specifically flavan-3-ols and their oligomers, which are all considered functional ingredients due to their associated health benefits."

Unsweetened chocolate, on the other hand, is too bitter for most people to enjoy, so researchers experimented with roasting treatments to modify the flavour – looking beyond basic tastes like sour and bitter – to make it more acceptable to consumers, according to Hopfer.

Alan McClure, founder of craft chocolate company Patric Chocolate and related consultancy Patric Food & Beverage Development, collaborated with Hopfer and Penn State to characterize the flavour and acceptability of the chocolates for the study.

The researchers reported in Current Research in Food Science that more intense roasting conditions, such as 20 minutes at 340 degrees Fahrenheit, 80 minutes at 275 degrees Fahrenheit, and 54 minutes at 304 degrees Fahrenheit, all resulted in chocolate consumers preferring unsweetened chocolate. Participants in the study, on the other hand, did not find 100% chocolate acceptable when made from raw or lightly roasted cacao, such as beans roasted 11 minutes at 221 F or 55 minutes at 147 F.

Hopfer noted that scientists' understanding of the variation of cacao-related bitterness has historically come from the instrumental investigation of the bitter compounds found in cocoa beans, but the Penn State study is novel in that it quantifies such variation using human sensory evaluation.

"Our study aimed to learn about bitterness perception and the liking of chocolate made from cacao roasted with a variety of roasting profiles in order to determine whether wide consumer acceptability of 100 percent chocolate is possible," she explained. "Other than varying how he or she roasts the beans, a chocolate maker doesn't have many other options to influence the flavour quality of 100 percent chocolate, and our results show that optimal roasting can adequately reduce bitterness."

(Source: Penn State)