A combination of enzymes and fermentation modifies bran structure and changes
the bioavailability of the bioactive compound, according to new studies
forming part of the European Union's large-scale HEALTHGRAIN project.
Bioprocessing of bran has potential for making it a better ingredient for use
in manufacturing nutritionally boosted cereal foods with high sensory quality.
The health benefits of whole grain and grain dietary fibre are well
documented, and dietary recommendations worldwide urge an increase in the
intake of foods containing more of these healthy ingredients. The intake of
both dietary fibre and whole grain foods is clearly less than recommended.
This is in part due to the technological challenge of achieving sensory
properties that appeal to consumers.
The presence of hard and
strong-tasting outer grain layers (bran) containing most of the
healthpromoting compounds demands new processing techniques to improve the
quality of cereal food. Bread is a staple food consumed in large quantities
throughout Europe, and is therefore a suitable food item for the purpose of
increasing European grain fibre intake. The purpose of this study was to
pre-treat cereal bran using bioprocessing techniques to make it better suited
for baking bread. A further objective of using these bioprocesses was to
improve the availability of healthy compounds of cereal bran, which involved a
study of the effects of processing on the bioavailability of phenolic
The bioprocessing techniques studied included
fermentation of wheat bran by using specific yeast and lactic acid starter
cultures and enzymatic treatments using different cell-wall degrading enzymes.
The most effective technique included a combination of cell-wall degrading
enzymes and fermentation. Fermentation of bran with yeast prior to baking
resulted in a higher bread volume and softer crumb of the samples of bread
fortified with bran. Moreover, bioprocessing of bran by enzyme-aided
fermentation increased the content of soluble fibre and the level of
phytochemicals, the potentially bioactive compounds in bran. An increase was
observed in the in vitro bioaccessibility of ferulic acid, the major phenolic
acid in wheat, along with a change in the profile of its human metabolites.
The significance to human health of these types of changes requires further
This way of bioprocessing of bran will create
opportunities for making it a better ingredient for use in cereal foods, as
well as in other food categories, thus aiding the manufacture of nutritionally
boosted cereal foods (bread, biscuits, cereals, snacks, yoghurts) with high
Besides improvements in the technological
quality and applicability of bran, the fact that bioprocessing changes both
the amount and uptake of biologically active compounds in the body opens up
new possibilities for tailoring the health effects of grain-based foods.
work formed part of the European Union project HEALTHGRAIN, and was conducted
by VTT Technical Research Centre of Finland in close collaboration with the
University of Maastricht and TNO. VTT focused on development of bran
processing and baking technologies, and also identified the human metabolites
of the bioprocessed brans following the gastrointestinal modelling and human
feeding trials performed at TNO and the University of Maastricht.
EU Integrated Project HEALTHGRAIN: The HEALTHGRAIN project has substantially
strengthened the scientific basis for a new generation of cereal based
products with enhanced health benefits. The project also has formed a network
of research organizations, industries and organizations communicating to
consumers that will continue as the HEALTHGRAIN Forum. Results of the project
will be presented in the HEALTHGRAIN Conference on May 5-7 in Lund, Sweden: www.healthgrain.org/pub
Technical Research Centre of Finland: VTT is a globally networked
multitechnological contract research organisation, providing high-end
technology solutions and innovation services. We enhance our customers'
competitiveness, thereby creating the prerequisites for the sustainable
development, employment, and wellbeing of society. www.vtt.fi
University of Maastricht: Maastricht University Medical Centre (MUMC),
located in the south of the Netherlands, integrates cutting-edge biomedical,
clinical, public health and primary care research and provides new insights
into health care and medical treatment. The NUTRIM School for Nutrition,
Toxicology and Metabolism of MUMC initiates and catalyzes translational
research into nutritional health benefits and risks focussing on metabolic and
chronic inflammatory diseases.
TNO: The Netherlands Organisation for Applied Scientific Research (TNO)
is an independent research organisation whose expertise and research make an
important contribution to the competitiveness of companies and organisations,
to the economy and to the quality of society as a whole, in The Netherlands,
Europe and world wide.
Katina, K., Laitila, A., Juvonen, R., Liukkonen, K-H., Kariluoto, S.,
Piironen, V., Landberg, R., Åman, P., Poutanen, K. Bran fermentation as a
means to enhance technological properties and bioactivity of rye. Food
Microbiology 24: 175-186, 2007.
Mateo Anson, N., Selinheimo, E., Havenaar, R.; Aura, A.-M., Mattila, I.,
Lehtinen, P., Bast, A., Poutanen, K., Haenen, G.R.M.M. Bioprocessing of wheat
bran improves in vitro bioaccessibility and colonic metabolism of phenolic
compounds; Journal of Agricultural and Food Chemistry. 57: 6148-6155, 2009