Food scientists from the National University of Singapore (NUS) have formulated a recipe for making healthier bread by adding a natural plant pigment, called anthocyanin, extracted from black rice. This new bread option gets digested at a slower rate—hence improving blood glucose control—and is high in antioxidants, among other health benefits. The findings of the study are published in Food Chemistry.
Bread is a popular staple food for many people around the world. Most breads contain a high amount of rapidly digestible starch, and hence many of them have a high glycemic index. Foods high on the glycemic index are rapidly digested and absorbed into the bloodstream quickly, causing a sharp increase in blood sugar levels and making them unsuitable for diabetic patients.
Anthocyanins belong to the group of flavonoids that are naturally occurring pigments in fruits and vegetables, and are responsible for the orange, red, violet, and blue colors observed in nature. Fruits, such as blueberries, grapes, blackberries, as well as grains and vegetables like black rice and purple sweet potatoes, are naturally rich in anthocyanins.
“Despite their antioxidant capacity and associated health benefits, the knowledge of using anthocyanins as an ingredient in food products, particularly semi-solid products, is very limited,” said Professor Weibiao Zhou, director of the food science and technology program at the NUS Faculty of Science.
The researchers found that digestion rates of the anthocyanin-fortified bread were reduced by 12.8% when 1% of anthocyanin extract from black rice was added into the bread dough and baked at the optimal condition of 200°C for 8 min. The digestion rate dropped further to 20.5% when the amount of anthocyanin extract increased to 4%. However, at 4% the bread became dense and less elastic.
Another area of interest for the team was to explore a way to incorporate anthocyanins into bread to improve its value as a health-promoting food. The team had previously conducted a study in 2014 to examine the degradation of anthocyanins during baking. They found that more than 80% of the antioxidant capacity was retained in the bread crust and crumb, even when baked at temperatures as high as 240°C for up to 12 min.
“Our results demonstrate that it is indeed feasible to create functional food products through anthocyanin fortification, using bread as an example. We hope to conduct further studies to incorporate anthocyanins into other food items, such as biscuits. Our team is also keen to explore opportunities to work with industry partners to introduce the anthocyanin-fortified bread to the market,” said Zhou.
