The new in-vitro study, conducted in collaboration with Prof Marco Gobbetti from the free University of Bolzano, Italy, reveals that oat, rye and wheat bran containing hydrolyzed AXOS fermented by lactic acid bacteria significantly increase the synthesis of short-chain fatty acids (SCFA) by colon microbiota.
Arabinoxylan oligosaccharides (AXOS) represent a class of fibers with prebiotic properties deriving from arabinoxylans, complex carbohydrates found in the cell walls of the starch endosperm, the aleurone layer and in pericarp tissues of cereals.
The prebiotic properties and health effects of AXOS have been widely described, largely linked to the production of short-chain fatty acids (SCFAs) due to AXOS fermentation by the gut microbiota
For around thirty years, AXOS have been used to improve dough consistency, bread volume and crumb structure through the solubilization of arabinoxylans.
However, until now, this ingredient's potential has not been fully investigated in terms of its ability to affect long-term intestinal ecosystem and metabolic health. Moreover, although fermentation and hydrolyzation are well-known processes to improve the bioavailability of Arabinoxylans and other nutrients, and to enable the food fortification with dietary fibers, the effect of such pre-treatments on the prebiotic benefits of AXOS from widely consumed cereals, like oat, rye and wheat brans, was not previously explored.
This in vitro simulation utilised the Simulator of the Human Intestinal Microbial Ecosystem (SHIME), to investigate and compare the effect of three different formulations containing hydrolyzed AXOS from oat, rye and wheat brans fermented by lactic acid bacteria and a non-hydrolyzed/nonfermented AXOS formulation (as a control).
"This is the first study exploring the middle-term dynamics (over a 2 week timespan) deriving from the intake of hydrolyzed and fermented formulations containing AXOS obtained from three cereal flours, and it shows a window into the ecological evolutions and plausible underlying mechanisms," the authors state.
Four cereal-based flours containing AXOS were produced and supplied by Puratos: hydrolyzed oat bran fermented with lactic acid bacteria (MOB); hydrolyzed rye bran fermented with lactic acid bacteria (MRB); hydrolyzed wheat bran fermented with lactic acid bacteria (MWB); and non-hydrolyzed and non-fermented wheat bran (WB) which was used as control.
The effects that these flours have on gut microbiota were studied using an in vitro simulator tool
The study demonstrated that feeding the colon microbiota with formulations containing hydrolyzed AXOS fermented by lactic acid bacteria significantly increased the synthesis of short-chain fatty acids (SCFA) by colon microbiota, with hydrolyzed and fermented rye bran displaying the highest effect.
After two weeks from the interruption of intake, SCFA concentrations significantly decreased but remained still significantly higher compared to the original condition.
Hydrolized AXOS feeding also affect the microbiome , with a significant abundance increase in Lactobacillaceae taxon after feeding with all fermented and hydrolyzed formulates. Hydrolyzed and fermented rye bran showed the highest changes. The fungal community, even if it had a lower variety compared to bacteria, was also modulated after feeding with AXOS formulations, with an increase in Candida relative abundance and a decrease in Issatchenkia.
On the contrary, the intake of non-hydrolyzed and non-fermented wheat bran did not produce relevant changes of relative abundances. After two weeks from intake interruption (wash out period) such changes were mitigated, and the gut microbiome modulated again to a final structure that was more like the original condition.
The report concludes: "This finding suggests that hydrolyzed AXOS fermented by lactic acid bacteria could have a more powerful prebiotic effect compared to nonhydrolyzed and non-fermented wheat bran, shaping the colon microbiome and its metabolic answer.
"However, the intake should be continuous to assure persistent effects. Opening a window into the ecological evolutions and plausible underlying mechanisms, the findings reinforce the perspective to explore more in depth the use of hydrolyzed and fermented AXOS as additional ingredient for bread fortification."
The commercial opportunity
Turning their scientific discovery into commercially available product, Belgium-based Puratos has launched a fermented wheat bran fibre named 'Sapore Baiota' that can be added to commercial breads to increase its nutritional content (mainly fiber) and health promoting benefits – with no compromise in the eating experience.
Raluca Florea, gut health leader for health and wellbeing at Puratos, explained: “We have learnt there are consumers who want to have the fibre enriched breads but don’t want to compromise on the taste and texture.
“Bread as a staple food, is a great application to integrate more gut healthy ingredients. However, the challenge that bakery innovators have this days is that adding high amounts of fibre can have a negative impact on product structure and sensory properties. Sapore Baiota opens a new opportunity for customers to innovate and bake great tasting healthier breads.”
Raluca Florea will attend IPA World Congress + Probiota next month (Feb 6-8) and join a panel discussion on the subject of the gut–brain axis.
Delegate registration is up to capacity but a waiting list is in operation.
"The Effect of Hydrolyzed and Fermented Arabinoxylan-OligoSaccharides (AXOS) Intake on the Middle-Term Gut Microbiome Modulation and Its Metabolic Answer"
Polo, A.; Albiac, M.A.; Da Ros, A.; Ardèvol, V.N.; Nikoloudaki, O.; Verté, F.; Di Cagno, R.; Gobbetti, M.