Extrusion limits the benefits of whole grains, suggests study

By Gill Hyslop contact

- Last updated on GMT

Extruded whole grains are a popular breakfast cereal. ©iStock/Pamela D Mcadams
Extruded whole grains are a popular breakfast cereal. ©iStock/Pamela D Mcadams

Related tags: Bacteria

Scientists have investigated how intestinal flora are affected by extruded whole grains, commonly used for breakfast cereals such as Cheerios.

Recent research by Nofima scientists suggests intestinal flora (or microbiota) is key to good health. Using young pigs as test subjects – because a pig’s anatomy is similar to that of humans – the scientists learned that extruded grains lessened the growth of microbiota as well as the type of flora.

To process or not to process?

The intestines of pigs that had eaten unprocessed whole grains had a higher proportion of beneficial lactic acid bacteria, as well as more butyric acid (BTA).

The BTA fatty acid is thought to play several beneficial roles in the gastrointestinal tract,​ including anti-inflammatory and anti-cancer properties, the research suggests. Extruding grain is a common practice today, as it preserves and improves the function of fiber. However, the structure of the grain is altered during the process.

Senior scientist Stefan Sahlstrøm explained that wholegrain flour is heated to 120–140°C while it is being kneaded, before being pressed through a die to obtain the desired shape.

 “Our experiments showed the pigs fed on unprocessed whole grains, both barley and oats, had a richer intestinal microbiota with more beneficial bacterial strains than the pigs fed on extruded whole grains,” ​added Birgitte Moen.

The dichotomy of extruding

Conversely though, studies have previously found that extrusion increases the absorption of antioxidants​ significantly.

Owned by the Norwegian government, Nofima is one of the largest institutes for applied food, fishery and aquaculture research in Europe.

Results from its studies assist food producers in developing new, healthy grain products.


Food & Function
Extrusion of barley and oat influence the faecal microbiota and SCFA profile of growing pigs’
Authors: Birgitte Moen, Ingunn Berget, Ida Rud, Anastasia S. Hole, Nils Petter Kjosb and Stefan Sahlstrøma.

DOI: 10.1039/C5FO01452B; http://pubs.rsc.org/is/content/articlelanding/2016/fo/c5fo01452b#!divAbstract

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