In vitro study for investigating the impact of decreasing the molecular weight of oat bran dietary fibre components on the behaviour in small and large intestine

Natalia Rosa-Sibakov (Corresponding Author), Noora Mäkelä, Anna Marja Aura, Tuula Sontag-Strohm, Emilia Nordlund

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The objective of this work was to evaluate the role of β-glucan molecular weight (Mw) and the presence of other carbohydrates on the physiological functionality of oat bran via an in vitro digestion study. A complete approach using three different in vitro digestion models (viscosity of the small intestine digest, reduction of bile acids and on-line measurement of gas evolution) was used to predict the physiological functionality of enzymatically modified oat bran concentrate (OBC). OBC was enzymatically treated with two β-glucanase preparations at three different levels in order to specifically decrease β-glucan Mw (Pure: purified β-glucanase) or β-glucan and other cell wall polysaccharides (Mix: commercial food-grade cell wall degrading enzyme preparation). The Mw of β-glucan in OBC was tailored to high (1000 kDa), medium (200-500 kDa) and low (<100 kDa) values. The amount of arabinoxylan-oligosaccharides varied from 0.3 to 4.7 g per 100 g of OBC when OBC was treated with the Mix enzyme at the highest dosage. When the enzymatically treated OBCs were studied in an upper gut model, a decrease in the viscosity of the digest simultaneously with the reduction of β-glucan Mw was observed. At a similar β-glucan Mw range, OBC samples treated with the Pure enzyme had lower viscosity than the samples treated with the Mix one, which also contained arabinoxylan-oligosaccharides. After enzymatic hydrolysis, the capacity of OBC to reduce bile acid was decreased regardless of the enzyme treatment used, and a positive correlation was found between β-glucan Mw and bile acid reduction (r = 0.99**). The production of colonic gases by the enzymatically treated OBC samples in an in vitro colon model showed an inverse correlation between β-glucan Mw and initial rate of gas formation (r = -0.9**), but no impact of arabinoxylan-oligosaccharides was observed. This study emphasised the complexity of factors affecting the functionality of oat components under physiological conditions and demonstrated the possibility to produce Mw-tailored oat fibre ingredients that could contribute to gut mediated health benefits.

Original languageEnglish
Pages (from-to)6680-6691
Number of pages12
JournalFood & function
Volume11
Issue number7
DOIs
Publication statusPublished - 2020
MoE publication typeA1 Journal article-refereed

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