Diabetic-friendly bread

02 March 2016 | Research
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Anthocyanin-rich black rice extract added to dough makes the bread more diabetic-friendly

Researchers from the Food Science and Technology Programme at NUS Science have come up with a recipe for healthier bread that may be suitable for diabetics. By adding a natural plant pigment called anthocyanin extracted from black rice, the new bread gets digested at a slower rate, thus helping to improve blood glucose control. Its high antioxidant content also offers additional health benefits.

The first study in which bread has been fortified with anthocyanin extract, the findings published in Food Chemistry last October open up exciting opportunities for making healthier and diabetic-friendly food products.

Anthocyanins are naturally occurring pigments in fruits such as blueberries, grapes, blackberries, as well as grains and vegetables like black rice and purple sweet potatoes. Previous research shows that anthocyanins are rich in antioxidant properties, which may help prevent cardiovascular and neurological diseases, cancer and inflammation. The compounds also contribute to obesity and diabetes control as they can inhibit digestive enzymes, hence reducing blood glucose levels.

Professor Zhou Weibiao, Director of the Food Science and Technology Programme who led the investigation, said, “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. Hence, we wanted to explore the feasibility of fortifying anthocyanins into bread, to understand how it affects digestibility and its impact on the various quality attributes of bread.”

The team chose bread for the study because it represents a staple and popular food worldwide, thus has more societal impact, he explained.

Current methods of making health-promoting bread mainly involve incorporating whole grains and fibres to slow down its digestion, among several health benefits. Dr Sui Xiaonan, a recent PhD graduate from the NUS Programme and first author of the project, elaborated, “Reducing the digestion rate of the bread may lead to a lower glycaemic index (GI) and slower absorption of the bread’s carbohydrates. This usually suggests a lower insulin demand, and could potentially improve long-term blood glucose control.”

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Dr Sui with his anthocyanin-fortified buns

The team determined that digestion rates of the anthocyanin-fortified bread decreased by 14.1 per cent when 2 per cent of anthocyanin extract from black rice was included in the bread dough and baked. The slow digestion rate compares favourably with normal white bread, which breaks down into sugar rapidly.

Even though the digestion rate dropped further to 20.5 per cent when the amount of anthocyanin extract was increased to 4 per cent, Prof Zhou noted that 2 per cent was the optimum level in terms of bread texture and volume.

The scientists are looking to work with the industry to commercialise the bread and expect the price to be comparable with some existing types of bread such as whole-grain products. 

See press release and media coverage.