Abstract
As part of a general trend, the grain processing industry faces the
challenge to produce new ingredients and foods with added value for
consumer health. In this context, the EU 6th Framework Integrated
Project HEALTHGRAIN, as part of its overall goal to provide the
scientific basis for increasing the intake of health-promoting compounds
in whole grains or their fractions, developed new technologies for
cereal ingredient and food manufacture. We here report on the outcome of
this work, with a main emphasis on wheat processing. It included
revisiting dry milling and exploration of wet enzyme-based fractionation
processes as well as fermentation in order to produce food ingredients
and/or foods with increased levels of health relevant components and
structural features delivering good sensory properties. A novel wheat
grain fractionation diagram was developed for incorporating bioactive
compounds in flour and removing the parts of the grain detrimental for
technological quality and safety. Processing eliminated the pericarp by
initial pearling to leave only the crease material attached to the
kernel, the resultant grain was milled to eliminate the bran crease
material, and the white flour was remixed with the pearling fraction to
incorporate as much as possible of the aleurone layer material into the
flour. A process for isolating aleurone from wheat bran starts with size
reduction of bran particles to favour tissue separation. The aleurone
tissue is then mechanically separated from the other seed coats by using
impact or shearing forces. After these fragmentations, the resultant
blend is mechanically separated. Further purification of aleurone cells
can be achieved using electrostatic separation to yield a powder
containing about 90% aleurone which has high antioxidant activity and
contains significant levels of vitamins, minerals, phytosterols, lignans
and other phenolic substances. The size distribution of the particles
ground to ultra-fine size was narrower for cryogenic grinding than for
ambient grinding. Further work dealt with wet processing. The abundance
of arabinoxylan (AX) in bran offered excellent possibilities for
manufacturing AX oligosaccharides (AXOS), which meet the criteria for
prebiotics. Xylanases release AXOS from AX with a yield which was
negatively correlated with the arabinose to xylose ratio of wheat bran
AX. In addition, hyperthermophilic xylanases allow producing AXOS in situ
during bread making without the negative impacts of AX extensive
hydrolysis on dough processing that some regular xylanases induce. Bran
fermentation with yeast prior to bread making leads to higher bread
volume and greater crumb softness. Moreover, bioprocessing of bran by
enzyme-aided fermentation increases the content of soluble fibre and the
in vitro and in vivo bioaccessibility of phenolic
acids. The quality of gluten-free breads can be improved by using lactic
acid bacteria with properties including antifungal activity, or the
production of exopolysaccharides or enzymes. Finally, studies and
demonstration activities were carried out on laboratory and pilot scale.
Original language | English |
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Pages (from-to) | 78-86 |
Number of pages | 9 |
Journal | Trends in Food Science and Technology |
Volume | 25 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2012 |
MoE publication type | A1 Journal article-refereed |