Is this the best thing since sliced bread?
Opening the door for food producers to make healthier white bread, an international group of scientists led by Rothamsted Research and the John Innes Centre have pinpointed genes responsible for the dietary fibre content of flour. The high-fibre white flour they produced has as much as twice the fibre of traditional white flour. A slice of typical white bread has about 1 g of fibre, wholemeal has about 3 g, whereas a slice from a high-fibre white loaf could contain up to 2 g.
The researchers say the new white flour is otherwise identical and makes a good quality white loaf — but with all the added health benefits that come from eating wholemeal bread, including reduced cancer, diabetes and obesity risks.
Writing in the journal PLOS ONE, lead author Dr Alison Lovegrove, Rothamsted Research, said the team had achieved the breakthrough by exploiting the results of an earlier genetic screen of over 150 different wheat varieties from around the world.
“We knew that the white flour made from one particular Chinese wheat variety, Yumai 34, was unusually high in fibre, but it’s not well suited for growing in the European climate,” she said.
“Using conventional breeding techniques, we crossed this high fibre trait into several other varieties. This allowed us to narrow down where in its genome the genes for high fibre are.”
Traditionally, crop varieties are improved by identifying plants with desirable traits and breeding from them. The problem with high fibre is it is not a trait you can identify by eye — and biochemical lab tests for it are slow and expensive.
“We’ve developed genetic markers that can easily be used by plant breeders to identify which individual wheat plants have the high fibre genes,” Dr Lovegrove said.
That will allow them to incorporate the high fibre into elite wheat lines — and opens the possibility of significant increases in dietary fibre intake for everyone, she added.
The quest to increase fibre in white bread through breeding had stalled in recent years, with various manufacturers instead producing loaves that contain both white and wholemeal flours, or have fibre from other sources added, in an attempt to address the issue.
Dr Lovegrove said: “We hope to go on and identify further genes that increase fibre content, thereby providing plant breeders, millers and food producers with even more options.”
While wholemeal is widely regarded as being much better for us, white bread still outsells it, making up three-quarters of the roughly 12 million loaves sold in the UK each day.
Taste, appearance, shelf life and price are the main reasons why consumers favour white bread, while the £8bn a year pre-packed sandwich industry prefers it as it refrigerates better.
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