Red dragon fruit peel compounds in bread boost antioxidants and slow starch digestion

Singaporean researchers have discovered that compounds extracted from red dragon fruit peel can be baked into bread to increase its antioxidant activity and slow starch digestion, which may lead to healthier everyday staple foods and cut food waste through upcycling.

The study infuses a purified betacyanin-rich extract derived from red dragon fruit peel into wheat bread at controlled concentrations. At an optimal fortification level of 0.75%, the extract improves dough structure and bread texture while delivering measurable nutritional benefits.

The research team was led by professor Zhou Weibiao, who heads the Department of Food Science and Technology at the National University (NUS).

“Functional staples such as purified-betacyanin-rich-extract-fortified bread provide a practical way to incorporate bioactive compounds into daily diets,” he comments.

“With diabetes rates increasing globally, improving the nutritional quality of commonly consumed foods may help reduce glycemic load and enhance antioxidant intake without requiring major changes in eating habits.”

Enhancing everyday staples

Betacyanins are more stable at common food pH levels and dissolve easily in water, the researchers highlight. This enables lower doses and more stable interactions with gluten during processing.

Additionally, in vitro studies suggest that betacyanins have higher bioavailability than anthocyanins, which suggests they may be more readily absorbed and could potentially deliver greater nutritional benefits.

Laboratory tests showed that betacyanins interact with gluten proteins in the dough. At moderate levels, the dough rises better, while high concentrations reduce dough elasticity and compromise bread quality.

To find the right balance, NUS researchers found that 0.75% betacyanin fortification is the most effective level for maintaining baking quality while achieving nutritional gains.

The fortified bread had substantially higher antioxidant levels than conventional bread and slower starch breakdown during digestion, resulting in a lower estimated glycemic index. The findings were published in Food Chemistry.

Upcycling food waste into functional ingredients

During a time when global food waste is at historically high levels, the NUS team stresses that there is added value in converting regularly discarded agricultural byproducts into functional food ingredients.

Because the team worked with a purified extract of dragon fruit instead of a whole fruit peel, they were able to achieve more accurate and consistent results while demonstrating how food waste can be reused in food production.

The scientists are now investigating how similar natural extracts can be added to other everyday foods, which can further slash food waste while improving food nutrition and industrial production efficiency.

Circular ingredient innovations with these triple benefits are increasingly common. In this space, Comet Bio produces Arrabina, a light-colored, fully soluble prebiotic fiber made from upcycled wheat crop leftovers. It is ideal for various applications, ranging from lemonade, snack bars, and supplements to ice cream.

Meanwhile, Kensing’s ingredient Sun E is marketed as a clean‑label tocopherol derived from sunflower seed byproducts. Vitamin E from sunflower oil provides more than twice the biological activity of synthetic versions as synthetic formulations.