Research from the Department of Food Science and Technology at the National University of Singapore (NUS) Faculty of Science has suggested that compounds extracted from red dragon fruit peel can be incorporated into bread to increase antioxidant activity and slow starch digestion.
The findings offer a potential pathway to healthier staple foods and reduced food waste.
Rather than exploring anthocyanin extracts, the NUS team shifted its focus to betacyanins derived from red dragon fruit peel.
This new approach offers a promising opportunity to fortify bread. The extraction methods for betacyanins are similar to those used for anthocyanins, but betacyanins offer distinct advantages.
They are more stable at typical food pH levels and dissolve readily in water, allowing lower dosages and more consistent interactions with gluten during processing.
Furthermore, in vitro studies suggest that betacyanins have higher bioavailability than anthocyanins, indicating they may be absorbed more effectively and provide greater nutritional benefits.
"Functional staples such as PBRE-fortified bread provide a practical way to incorporate bioactive compounds into daily diets," said Prof. Zhou, who heads the NUS Department of Food Science and Technology.
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.
Laboratory tests have demonstrated that betacyanins interact with gluten proteins in dough. At moderate levels, these compounds enhance dough rising, while high concentrations can reduce elasticity and compromise bread quality.
Researchers at NUS identified a fortification level of 0.75 per cent as the most effective for maintaining baking quality while also providing nutritional benefits.
The fortified bread exhibited significantly higher antioxidant levels than conventional bread and showed slower starch breakdown during digestion, resulting in a lower estimated glycemic index.
These findings were published in the scientific journal Food Chemistry in December 2025.
In light of the rising global food waste crisis, the NUS team recognises the potential to convert agricultural by-products, which are often discarded, into functional food ingredients. Instead of utilising whole fruit peel, the researchers opted for a purified extract to achieve more precise and consistent results, illustrating how food waste can be repurposed in food production.
The researchers are now exploring how similar natural extracts can be incorporated into other common foods to enhance nutrition, improve production efficiency and further reduce food waste.