Penn State’s Sensory Evaluation Center in Food Science’s Department of Food Science conducted a new study to this end, according to the findings of a team of researchers. A total of 145 people participated in the study, which used 27 different kinds of 100 percent chocolate made from variously roasted cocoa beans. Each day, they were given five different samples to taste.

Consumers dislike chocolate because of its bitterness and astringency, according to a study led by Rasmussen Career Development Professor in Food Science Helene Hopfer of the College of Agricultural Sciences’ research team. The study found that roasting can help reduce these bitterness and astringency qualities in chocolate.

To reduce their sugar intake or take advantage of the perceived health benefits, more people are turning to darker chocolates with less sugar and more cacao, according to her. A flavonoid subtype known as flavan-3-ols and their oligomers, which are all considered functional ingredients because of their associated health effects, are particularly abundant in dark chocolate.

Since most people dislike the bitter taste of unsweetened chocolate, researchers began experimenting with roasting treatments to mask the bitterness and make the chocolate more appealing to consumers, according to Hopfer.

Researchers from Hopfer and Penn State collaborated with Alan McClure, founder of craft chocolate company Patric Chocolate and related consultancy Patric Food & Beverage Development, on a study to determine the taste and acceptability of various chocolates for human consumption.

McClure chose cocoa beans from Madagascar, Ghana, and Peru, harvested in 2018 and 2019, as part of his doctoral degree dissertation research. It was shipped to Penn State from Columbia, Missouri, where it was remelted with the help of Hopfer and sliced into small discs for sensory evaluation by his team of tasters.

According to McClure, who was fascinated by the way study participants responded to his 27 different preparations made entirely of chocolate, what he learned from this research will help him and other chocolate manufacturers who use cocoa roasters develop new products by better understanding the subtle chemical changes that occur during the roasting process.

According to research published in the journal Current Research in Food Science, consumers prefer unsweetened chocolate when it has been roasted for longer periods of time at temperatures as high as 340 degrees Fahrenheit for 20 minutes, 275 degrees Fahrenheit for 80 minutes, and 304 degrees Fahrenheit for 54 minutes. Research participants, on the other hand, did not like the taste of 100% chocolate made from raw or lightly roasted cacao, such as beans roasted for 11 minutes at 221 F or 55 minutes at 147 F.

Scientists have traditionally studied the bitter compounds in cocoa beans using instruments, but the Penn State study is novel because it relies on human sensory evaluation to quantify this variation, according to Hopfer.

In order to determine whether or not 100 percent chocolate could be accepted by a wide range of consumers, she conducted her study with the goal of learning how people perceive bitterness and how they respond to different roasting profiles. According to our findings, “A chocolate maker doesn’t have many other options to influence the flavor quality of 100 percent chocolate except to vary how he or she roasts the beans, and our results show optimal roasting can adequately reduce bitterness.”