Keeping Chocolate Sweet While Cutting Sugar

Back in the 1990s, Gregory Ziegler, now distinguished professor of food science at Pennsylvania State University, worked on using then-new bulking agents as fat replacers in chocolate. Recently, he teamed with two Penn State colleagues to apply some of that work to determine if there is a substitute for sugar that wouldn’t negatively affect chocolate’s texture and flavor. Findings from their research were published in the Journal of Food Science.

“The fundamental idea is that in chocolate there’s an excess of sugar from the standpoint of generating sweetness,” Ziegler says. “So the concept is you could replace a goodly portion of the sugar and not change the perception of sweetness.”

However, reducing sugar means upping or adding something else. The most obvious thing to do, Ziegler says, is to increase the cocoa liquor content, but that adds bitterness and cocoa flavor, which can throw the taste profile out of balance. The solution is to find a bulking agent that won’t change the flavor, he says. A second problem is that the ingredients used to replace sugar can change the chocolate’s texture.

“What we had to figure out was can we find a bulking agent that’s neutral in flavor that won’t influence the texture of the chocolate,” Ziegler summarizes.

The structure of cocoa powder has commonalities with some flours, including nut flours, he says, and that triggered the idea that flour with the same or similar-sized starch particles could be a good option. The starch particles in cocoa measure about 12 microns, so the researchers looked for a flour with starch granules of less than 20 microns in size. They identified oat starch and sweet rice starch. In the case of the latter, the compound granule is slightly larger, but it’s made up of smaller granules, which can be ground down to a finer size. Oat starch alone would have been an even better choice, says Ziegler, but it’s not commercially available in large amounts, and the team wanted options that would be accessible for food industry use.

The Right Amount of Sweetness

First, the researchers made four variations of chocolates using rice and oat flours in place of sugar at 25% and 50% as well as a sugar version with less refined sugar and a control with 54% sucrose. They used palm oil and coconut oil in place of cocoa butter so they wouldn’t have to temper the chocolate. This means that their mixture isn’t legally considered chocolate, but the point was to test the concept, so that wasn’t a concern, Ziegler explains.

The Penn State team first conducted a sensory test with 66 tasters who did a blind taste test of two pieces of each sample plus the control under red light conditions. The control chocolate was tasted first and then the sugar-reduced chocolates, with the tasters alternating between noses clipped and unclipped. In a second sensory test, 90 tasters sampled three versions, one with 54% sucrose and one each with an oat flour and sweet rice flour replacement.

Overall, chocolates with 50% of the sugar replaced by either oat flour or sweet rice flour were judged too different from the control. However, the tasters found no appreciable difference with the 25% replacement of both substitutes. The chocolates with sweet rice flour were found to have a grittier texture, while those made with the oat flour had a preferable, smoother texture.

In fact, the 25% oat flour replacement version was ranked highest for “sweetness liking.”

Ziegler says this indicates that there’s probably more sugar than needed in commercial chocolates and also that oat flour is a feasible sugar replacement. Oat flour has a slight oaty taste, but Ziegler doesn’t think that’s a deal-breaker. “It’s not a typically offensive flavor, especially at the levels we were using,” he says.

Ziegler and his colleagues are continuing to work on the project. There are interesting possibilities, he says. For example, a small granular starch that is also a resistant starch could be a source of additional dietary fiber.

“You can take a product that’s already got some good health benefits; it’s got this neutral fat, you can get rid of some of the sugar, maintain some sweetness, but then add this fiber component through the starches,” he explains.ft