Barley milling and utilization of fractions
Barley grain is an excellent source of several nutritious components.
November 15, 2007 By Top Crop Manager
Barley grain is an excellent source of several nutritious components. Barley
fractions enriched in various bioactive constituents can be obtained through
different processes including milling. "One approach is to use extraction
methods to remove active compounds from barley and use them as nutraceuticals
and food ingredients," explains Dr. Marta Izydorczyk, program manager of
barley research at the Grain Research Laboratory with the Canadian Grain Commission
in Winnipeg. "Another approach, and the one we prefer, is to fractionate
barley by chemical-free physical processes like milling, rather than using extraction
Roller milling, for example, has the potential to fractionate the grain into
various streams with unique composition and functionality. The roller milling
of unpearled barley can fractionate this grain into flour and a fibre rich fraction.
Depending on the type of barley, the flour can become a source of starch with
unique characteristics and digestibility. The fibre rich fraction holds promise
as a natural and functional food ingredient, as it is especially enriched in
beta-glucans and other less familiar dietary fibre components such as arabinoxylans.
Recent studies are indicating that arabinoxylans might have similar health benefits
as beta-glucans. "The milling fractions also include other bioactive components
such as vitamin E, phenolic compounds which are known for their antioxidant
activity, and other vitamins and minerals," says Izydorczyk.
"The advantage of milling is, therefore, the possibility of generating
fractions enriched in a particular component without eliminating the synergistic
effects that might exist among different constituents," she explains. "During
an extraction process, usually only one component is targetted, which may, in
fact, only be active to its full potential when other components are present."
Extraction tends to remove the other components, and reduce the potential for
the synergistic effect and benefits of more complete fractions. "We don't
yet fully understand how these components synergistically interact with each
other to give us the best nutritional quality."
In the research, hulless barley genotypes were used including those with high
amylose, waxy and normal starch characteristics. "We have found differences
in functional and nutritional properties in these barley grains, and our research
has shown that high amylose hulless varieties might have another advantage because
they contain slowly digestible starch (low glycemic index). Our interest in
the high amylose barley genotypes is for both their high dietary fibre content
and the starch they contain with unique and desirable qualities," explains
Izydorczyk. "We're working with barley breeders like Dr. Brian Rossnagel
on these genotypes and sharing our research results with him."
The fibre rich barley fractions have performed well in several wheat-based
products such as pasta, bread and noodles. They significantly increased the
total dietary fibre content of these products as well as showed a potential
of slowing the digestibility of starch. Izydorczyk notes that the replacement
of wheat flour with the barley fibre rich fractions usually results in darker
products, which may be appealing especially to health conscious consumers who
are aware that the white colour of cereal-based products is achieved by using
refined but nutrient depleted ingredients.
"One of the other new uses we've been investigating for the starch enriched
fractions is the potential to use them as an adjunct in brewing as a replacement
for corn or rice flour that is typically used today," says Izydorczyk.
"If we could replace these import products with starch enriched barley
fractions, that would be good for our grain industry." Izydorczyk's research
group is also working to continually improve the milling process. They have
moved from an experimental mill into a larger mill, and have been working to
simplify the milling process and procedures.
"Our goal is to develop a simple commercial process that industry can
utilize to create these milling fractions that are enriched in particular components
for use in food processing," explains Izydorczyk. "We're also continuing
to do research on other aspects, such as fraction enrichment, most beneficial
particle size and the most useful form and concentrations of the fibre fractions."
Izydorczyk is looking forward to having industry utilize this technology, and
is willing to work with them and share as much information as possible to help
get them started. -30-