The development of roller milling in the 19th century led to white bread becoming affordable and popular in many countries by the 1880s. However, concerns were raised about the nutritional impact of replacing wholemeal bread with white bread. Two early critics in the UK were doctors Allinson and Yates, who advocated for wholemeal bread. Allinson established a milling company producing wholemeal bread that still operates today. Yates founded the Bread Reform League to promote higher extraction flours. While white bread remained dominant, interest in whole grains has increased in recent decades due to research establishing their health benefits. New milling approaches aim to increase flour extraction rates while maintaining bread quality and consumer acceptability.

1. B
ecause bread has long been the staple
food in temperate countries, this
led to massive changes in diet, with
coarse wholemeal or brown breads
being almost completely replaced by
white products in the UK by 1880.
Although the science of nutrition was
then in its infancy, concerns were
nevertheless expressed about the
impact of this change in diet on the nutrition and health of the
population. Foremost among the critics of white bread in the UK
were May Yates and Thomas Allinson.
Allinson qualified as a doctor in 1879 and established a
practice in London. He believed that diet was crucial for health,
and particularly advocated the consumption of stone ground
wholemeal wheat. He was frequently in dispute with orthodox
medicine and was “struck off” (disqualified from practicing) in
1892, having been found guilty of “infamous conduct” (self-
promotion). In the same year he purchased a stone mill and
established a milling and baking company that continues to
produce wholemeal bread to the present day.
By contrast, May West was not trained as a scientist but became
convinced of the benefits of wholemeal bread during a visit to
Sicily. She founded the Bread Reform League in 1880 and spent
40 years campaigning for the use of high extraction (about 85
percent) flours. The late 19th Century also saw the introduction
of improved “patent” breads, the most well known being “Hovis”
which is enriched in wheat germ. Despite the compulsory
production of high extraction and wholemeal breads in the
UK during the two World Wars, white bread has remained the
favourite for much of the British population, and in many other
countries.
Although those who promoted improved breads in the 19th
Century recognised the importance of fibre and protein, the health
benefits were not soundly established until the early 20th Century,
with the discovery of vitamins and the recognition that these
are depleted when the bran and germ are removed to produce
white flour. Since then, many studies have been reported positive
relationships between flour extraction rate and the contents of
“beneficial” components in flour, including B vitamins, Vitamin
E, minerals, fibre and “bioactive” phytochemicals, with the
differences in concentrations of these components between
wholemeal and white flour exceeding ten-fold in some cases.
Wholegrain and health
Recent interest in the relationship between wheat and health
has been stimulated by the wholegrain movement, which can
be dated from the approval granted by the US Food and Drugs
Administration in 1999 that “Diets rich in whole grain foods
and other plant foods and low in total fat, saturated fat, and
cholesterol, may help reduce the risk of heart disease and certain
cancers." This has stimulated interest from both industry and
academics and the establishment of bodies to promote wholegrain
consumption, such as the Whole Grains Council, Grains for
Health Foundation and Healthgrain Forum.
The role of vitamins and minerals in health is well established
but recent attention has focussed on dietary fibre. There is strong
scientific evidence that increased consumption of cereal fibre,
Improving the health
benefits of bread
by Peter Shewry, Distinguished Research Fellow, Department of
Plant Biology and Crop Science, Rothamsted Research, UK
The development of roller milling in the 19th Century
made white bread affordable to all social classes for
the first time, leading to a love affair with white bread,
which remains in many countries to the present day.
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2. particularly in wholegrain, results in reduced risk of a range of
chronic diseases including type two diabetes, stroke and some
types of cancer (notably colorectal). The scientific evidence
for the role of dietary fibre and other cereal carbohydrates in
health has been reviewed in detail in a recent report from the
UK Scientific Advisory Committee on Nutrition. Although, the
roles and benefits of “bioactive” phytochemicals remain to be
established, few would dispute that increasing flour extraction
rate could have a significant impact on the health of consumers.
Wheat grain structure and milling
In botanical terms the wheat grain is a single-seeded fruit, called
a caryopsis. It consists of three main parts, which have different
functions and compositions. The central part of the grain is the
endosperm, which accounts for about 90 percent of the total
grain.
This is essentially a storage tissue, being packed with starch and
protein, which are digested to support the growth of the seedling
during germination. However, the outer layer of endosperm cells
differ from the others, being rich in dietary fibre, protein, oil, B
vitamins, minerals and phytochemicals. These outer aleurone
cells account for about 6.5 percent of the grain. The embryo is
relatively small, accounting for about 3 percent of the total grain,
and develops into the seedling on germination.
It is similar in composition to the aleurone, except for a lower
proportion of dietary fibre. Outside of the embryo and endosperm
are the seed coat (testa) and the fruit coat (pericarp)) which
provide protection to the grain (see figure). These outer layers are
very rich in fibre and associated phenolic acids but not in other
beneficial components. Conventional milling has been developed
to separate the starch-rich cells of the central endosperm (called
the starchy endosperm) from the outer layers, aleurone and germ,
which are together recovered as bran.
The process is remarkably effective, with the yield of white
flour approaching 80 percent of the total grain. However, as
flour yield approaches and exceeds 80 percent there is increasing
starchy
endosperm
germ
Aleurone
pericarpandtesta
Milling and Grain - November 2015 | 41
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3. “contamination” with bran tissues, particularly with the aleurone,
which adheres tightly to the outer starch-rich cells (figure).
Hence, the concentrations of beneficial components increase
significantly as extraction rate rises.
Challenges to increasing flour extraction rate for bread
making
Increasing the flour extraction rate poses challenges for food
processing and for the consumer acceptability of the products.
Increasing the content of bran in bread-making flour reduces
the acceptability to consumers accustomed to consuming white
bread, due to the grittiness associated with bran particles and to
the colour and flavour (more wheaty and bitter with an aftertaste)
associated with the presence of proanthocyanidin pigments in the
testa of the “red” grained types of wheat which are largely used
for bread making.
In theory, the latter problem is easy to eliminate as “white”
grained wheats are available which lack the pigment and
associated flavour. However, white wheats are highly susceptible
to “pre-harvest sprouting” when subjected to cool and wet
conditions at harvest, leading to loss of value as sprouted grain
cannot be used for food processing. Hence, white wheats are
not widely cultivated and the grain is too expensive to be used
except for premium products. It has not been possible to separate
the red colour from the resistance to sprouting by conventional
plant breeding but work in progress on understanding the precise
relationships between the two seemingly unrelated phenomena
might allow the use of modern molecular tools to produce white
wheats that are also resistant to sprouting.
It should also be noted that higher intrinsic processing quality
is required for producing wholemeal and high extraction breads
than for white bread. This is because processing quality is mainly
determined by the gluten proteins, which are located exclusively
in the white flour. These proteins are therefore diluted by about
25 percent in wholemeal, and to a correspondingly lesser extent
in high extraction flours. It is therefore necessary to use grain of
higher protein content and/or protein quality, or to supplement
low protein flour with “vital gluten” produced by the industrial
separation of starch and gluten from flour.
New approaches to producing enhanced flours
Two recent multinational projects supported by the European
Union have focused on developing new technologies to improve
the quality and acceptability of whole grain and high extraction
rate bread.
One option, which was explored, is to eliminate the more
unpalatable fibre-rich outer layers of the bran while retaining the
inner bran, which includes the nutrient-rich aleurone layer. This
cannot be achieved by simple abrasion (debranning) of whole
grain because of the oval shape and the presence of a crease.
The Health grain programme (2005-2010) therefore developed a
process in which the grain was pearled twice, initially to remove
the outer bran (approx three percent dry wt) and then the inner
bran (up to 15 percent original dry wt). The first fraction was
discarded while the second fraction, which was enriched in the
aleurone layer, retained. Although the pearling removed most of
the bran some remained in the crease region. The debranned grain
was therefore milled and sieved using conventional procedures
and the white flour recombined with an appropriate proportion
of the second pearling fraction to give “Healthflour” which was
enriched in beneficial components and had improved processing
properties and higher acceptability.
Alternative approaches in the same project were to mechanically
separate the aleurone layer using different types of mills to
produce “aleurone powder” as an ingredient, and to finely grind
the bran (micronisation) prior to fractionation by electrostatic
separation. Miconisation also has the advantage that it increases
the bioavailability of minerals, vitamins and phytochemicals.
Following on from Health Grain, the Healthbread project
(2012-2014) developed a range of concentrates from aleurone
and wholegrain, which were successfully used by commercial
partners using either long fermentation or sough dough systems.
There is no doubt that such new approaches can be used to
produce bread which combines increased health benefits with
good consumer acceptability. However, they will inevitably
increase the cost of production, and current options are also more
applicable to the low volume production of artisan breads than
high volume factory production. Hence, their impact on the
health of the whole population may be limited and cheaper and
more widely applicable solutions should continue to be sought.
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