New legume flour improves blood glucose response to white bread
Bread is one of the UK’s favourite foods. According to the association of UK Flour Millers, the product is purchased by 99.8% of British households, with the equivalent of approximately 11m loaves sold each day. The majority (60-70%) of this bread is white.
While undoubtedly a popular staple, bread has a high-glycaemic index due to its highly digestible wheat starch. When this starch is quickly digested to glucose in the body, it causes a large spike in blood glucose levels. It is thought that helping consumers better manage their blood glucose could help reduce obesity and type 2 diabetes.
With rising public health concerns, regulating the glycaemic impact of staple foods is attracting ‘significant interest’, according to researchers at King’s College London and the Quadram Institute.
A potential solution to this issue has been identified in a new ingredient derived from chickpeas
Finger on the pulse
The novel ingredient, created from intact cell powder (ICP), is made using a specially-developed milling and drying process.
Whereas conventional milling and processing methods rupture plant cells – which exposes the starch and makes is more digestible – the researchers’ method preserves the cellular structure. This makes the chickpea starch more resistant to digestion.
With funding from the UKRI’s Biotechnology and Biological Sciences Research Council (BBSRC), the researchers investigated the commercial potential of the ICP flour, referred to as PulseON. The novel ingredient, they say, expands the possibilities for including large amounts of resistant starch in processed foods to improve nutritional quality.
“Incorporating our new type of flour into bread and other staple foods provides an opportunity to develop the next generation of low glycaemic food products to support public health measures to improve health through better diets,” said Quadram Institute’s Dr Cathrina Edwards.
“Consumers replacing wheat bread with PulseON enriched bread would benefit not only from the type 1 resistant starch, but also from the higher fibre and protein content.”
Lowering blood glucose response to white bread by 40%
To investigate exactly how efficient PulseON is in lowering blood glucose levels, the researchers undertook a study wherein some wheat flour in bread rolls was replaced with PulseON.
Published in the journal Food Hydrocolloids, the double-blind randomised study saw 0%, 30% or 60% of wheat flour in a standard white wheat bread recipe swapped out for the novel ingredient.
Participants ate each type of bread roll for breakfast, without knowing which type of roll they were consuming. The rolls were eaten in random order on separate days. The researchers then recorded the participants’ glucose levels using continuous glucose monitors.
Findings revealed that blood glucose responses to PulseON enriched bread were, on average, 40% lower than after eating the control breads.
Scientists also studied the digestion of starch in each bread type using biochemical and microscopy techniques in a laboratory. Experiments revealed that two hours after digestion, the type 1 resistant starch remained undigested. The wheat starch, on the other hand, was digested within this time frame.
According to the research team, such findings suggest the lower glucose response to PulseON enriched breads can be directly linked to the fact the resistant starch enclosed in the chickpea ingredient had not been digested.
Next steps towards commercialisation
The study outcome raises the possibility of PulseON enriched bread products being used to help improve the management of diabetes. Further research would be required to investigate this.
What is promising for the commercialisation potential of PulseON is the participants’ sensory response to the enriched rolls. During the study, subjects gave similar scores for texture and taste for all white bread products – including those made with the novel ingredient.
And quality testing suggested that effects on bread texture and appearance were subtle when using PulseON. These were more noticeable when large amounts of the new flour was incorporated. While more sensory testing is required, the initial findings are encouraging.
Having patented the technology, the research group is eying commercialisation. It is also exploring ingredient applications in a wider range of food products, and hopes to undertake further trials in subjects with prediabetes and type 2 diabetes.
Source: Food Hydrocolloids
‘The impact of replacing wheat flour with cellular legume powder on starch bioaccessibility, glycaemic response and bread roll quality: A double-blind randomised controlled trial in healthy participants’
Published online 28 December 2020
Authors: Balazs H. Bajka, Ana M. Pinto, Jennifer Ahn-Jarvis, Peter Ryden, Natalia Perez-Moral, Alice van der Schoot, Costanza Stocchi, Catherine Bland, Sarah E. Berry, Peter R. Ellis and Cathrina H. Edwards.