Adding natural plant
pigment extract to bread slows down its digestion rate and adds health benefits
Newswise, March 28, 2016 — A team of food scientists from the
National University of Singapore (NUS) has successfully 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. This is the first study where anthocyanin extract has been
fortified into a bread product, and the findings open up new possibilities of
creating healthier, diabetic-friendly food products.
Bread is a popular staple food for many people around the
world. Most bread contain a high amount of rapidly digestible starch, and hence
many of them have a high glycemic index.
Food 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.
In addition, rapid digestion of bread may result in people
consuming more bread than required to make up the hungry feel. The excessive
consumption of bread could increase the risk of overweight and obesity, and
their associated diseases, such as Type II diabetes.
The anthocyanin-fortified bread created by NUS researchers
could potentially bring health benefits to consumers looking for a healthier
option to normal bread.
Fortifying bread with anthocyanins
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 colours 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.
Scientific studies have shown that anthocyanins are rich in
antioxidant properties and may help prevent cardiovascular and neurological
diseases, cancer, and inflammation.
Anthocyanins are also known to play a role in controlling
obesity and diabetes as they can inhibit digestive enzymes and hence reducing
blood glucose levels.
Professor Zhou Weibiao, Director of the Food Science and
Technology Programme at the NUS Faculty of Science, 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.”
Currently, approaches for developing health-promoting bread
are dominated by adding whole grains and fibres in bread, partly aiming to slow
down its digestion among several health benefits.
Dr Sui Xiaonan, a recent PhD graduate from the Food Science
and Technology Programme at NUS and first author of the study said,
“Reducing the digestion rate of the bread will lead to a lower
glycemic index and slower absorption of the bread’s carbohydrates. This usually
suggests a lower insulin demand, and could potentially improve long-term blood
glucose control. Our study explores an alternative way of producing functional
bread that delivers health benefits to consumers.”
Lowers digestion rate
The NUS team, led by Prof Zhou, found that digestion rates of
the anthocyanin-fortified bread reduced by 12.8 per cent, when 1 per cent of
anthocyanin extract from black rice was added into the bread dough and baked at
the optimal condition of 200 degree Celsius for 8 minutes. The digestion rate
dropped further to 20.5 per cent, when the amount of anthocyanin extract
increased to 4 per cent.
High antioxidant capacity
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 per cent of the antioxidant
capacity was retained in the bread crust and crumb, even when baked at
temperatures as high as 240 degree Celsius for up to 12 minutes.
“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,” Prof Zhou said.
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