Researchers have developed a method to enhance bread by incorporating compounds from red dragon fruit peel, a commonly discarded by-product.
A team led by Professor Zhou Weibiao at the National University of Singapore (NUS) has discovered a way to turn red dragon fruit peel, which is usually discarded, into a functional ingredient for bread.
By extracting bioactive compounds and adding them to dough, the researchers increased antioxidant activity and slowed starch digestion, pointing to a simple way to improve a widely consumed food.
Enhancing the nutritional value of everyday staples
The researchers incorporated a purified betacyanin-rich extract (PBRE) from red dragon fruit peel into wheat bread at controlled levels. At an optimal concentration of 0.75 percent, the extract improved dough structure and bread texture while providing clear nutritional benefits.
Building on earlier work with anthocyanins, the team shifted focus to betacyanins from red dragon fruit peel as an alternative for bread fortification. Although the extraction process is similar, betacyanins are more stable at typical food pH levels and dissolve readily in water. This allows for lower usage levels and more consistent interaction with gluten during baking. In addition, in vitro studies suggest betacyanins have higher bioavailability than anthocyanins, meaning they may be absorbed more efficiently and offer greater potential health benefits.
“Functional staples such as PBRE-fortified bread provide a practical way to incorporate bioactive compounds into daily diets. With diabetes rates increasing globally, improving the nutritional quality of commonly consumed foods may help reduce glycaemic load and enhance antioxidant intake without requiring major changes in eating habits,” said Prof Zhou, who heads the NUS Department of Food Science and Technology.
Balancing Dough Performance and Nutritional Gains
Laboratory experiments showed that betacyanins interact with gluten proteins in the dough. At moderate levels, they improve dough rise, but at higher concentrations they reduce elasticity and negatively affect bread quality. The researchers determined that 0.75 percent fortification provides the best balance between baking performance and nutritional improvement.
The fortified bread showed significantly higher antioxidant levels than standard bread. It also slowed starch digestion, leading to a lower estimated glycemic index.
Turning food waste into functional ingredients
With global food waste at high levels, the team highlights the potential of converting agricultural by-products into useful food ingredients. Instead of using whole fruit peel, the researchers used a purified extract to ensure more consistent and precise results, while demonstrating a practical way to reuse food waste in food production.
The team is now exploring how similar natural extracts can be applied to other everyday foods. Their goal is to support more efficient food production while improving nutritional quality and reducing waste.
Reference: “Incorporation of purified betacyanin-rich extract from Hylocereus polyrhizus peel into bread and its impacts on dough properties, bread baking quality, and nutritional attributes” by Xiaojuan Xu, Serena Wong Mun Rui, Yingfen Jiang, Kelly Natalia Djohari and Weibiao Zhou, 3 November 2025, Food Chemistry.
DOI: 10.1016/j.foodchem.2025.146943
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