Development and optimisation of food products low in FODMAPs: an investigation of dietary fibres in low FODMAP products and the reduction of FODMAPs via bio-technological processes

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Atzler, Jonas J.
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University College Cork
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Cereal-based products – a stable food source in the western world- are high in fructans and α-galactooligosaccharides (GOS). These carbohydrates belong to the group of fermentable oligo-, di-, monosaccharides and polyol (FODMAP), which were shown to trigger symptoms of irritable bowel syndrome. A diet low in FODMAPs is reported to relieve symptoms in over 70 % of patients However, the availability of nutritious and appealing food products (e.g., sufficient dietary fibre content and good techno-functional quality) suitable for that diet is very limited. Therefore, this thesis investigated two approaches and their potential for overcoming this challenge. Firstly, three enzymes (invertase, inulinase and α-galactosidase) were used to investigate the targeted degradation of fructans and GOS. Inulinase and invertase degrade both fructans and GOS, while α-galactosidase only degrades GOS. Inulinase was the most efficient in degrading both fructans and GOS since it led to the degradation of 90 % of both oligosaccharide types. However, the use of inulinase and invertase resulted in the production of two degradation compounds – fructose in excess of glucose and melibiose and its higher homologues- which have the potential to act as FODMAPs. The second approach was to fortify products with dietary fibres (DFs) beneficial for IBS-patients, based on substituting wheat flour with wheat starch and gluten. The application of two insoluble (bamboo fibre and cellulose) and two soluble-viscous DFs (psyllium and guar gum) was tested in bread and pasta. Two different concentrations of these DFs (3 g/ 100g and 6 g/100 g) were used to produce a bread. The application of these DFs in a bread system, highlighted that the effects on the bread quality significantly depend on both the DFs' solubility and viscosity. All DFs decreased the specific volume of breads and increased the hardness after 0 h and 24 h. Despite these effects, the techno-functional quality was similar to wheat bread fortified with DF (3 g/100 g and 6 g/ 100 g of wheat bran). Additionally, a dose dependency of these effects was found: using the DFs in a concentration of 6 g/100 g resulted in an enhancement of the observed effects. Ultimately, the addition of all fibres led to an improvement in the nutritional quality with reduced in vitro starch digestibility. All four DFs mentioned above were added to a pasta system in a concentration of 6 g/100 g. The effects on the techno-functional properties depended on the DF's solubility, viscosity, and particle size. Both cellulose and guar gum showed the most potential with acceptable techno-functional properties (e.g., hardness, optimal cooking time, cooking loss). The application of highly viscous DFs (especially guar gum) positively influenced the in vitro starch digestibility. For all DF fortified pasta, no significant difference in the sensory properties compared to the unfortified pasta was found, suggesting an acceptable sensory quality. Finally, a combination of three different DFs (resistant starch, cellulose and corn fibre rich in arabinoxylans) was used to produce a fibre-enriched low FODMAP biscuit. Using the response surface method (RSM) for finding the best combination of the three ingredients resulted in a biscuit with a DF content of ~15 % and an improved quality compared to the unfortified biscuit. The sensory quality of the optimised biscuit was similar to a wholemeal biscuit and the unfortified low FODMAP control biscuit. Furthermore, the fibre-enriched biscuits showed an improved in vitro starch digestibility. Overall, the findings of this thesis offer a set of tools for the developments of low FODMAP products. On the one hand the suitability of IBS-beneficial fibre for developing nutritious and appealing products suitable for a low FODMAP diet is a reliable approach, without the need of any further FODMAP reduction techniques. On the other hand, also the targeted use of FODMAP degrading enzymes is a promising approach; if native fructans and GOS are present (e.g., whole wheat or rye-based products) these can be efficiently degraded in combination with fermentation-based techniques.
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FODMAPs , Dietary fibre , IBS
Atzler, J. J. 2023. Development and optimisation of food products low in FODMAPs: an investigation of dietary fibres in low FODMAP products and the reduction of FODMAPs via bio-technological processes. PhD Thesis, University College Cork.