Characterization of fructans and dietary fibre profiles in raw and steamed vegetables

Abstract

Dietary fibre (DF) has many positive effects on human health associated with its functionality in the gastrointestinal tract. These benefits vary according to the type of DF. Vegetables can be a natural source of DF in the diet. However, to provide adequate nutritional advice, the content and profile of their various DF types must be characterised. This study aimed to determine the DF profile of 29 vegetables cultivated in Wallonia (Belgium) and the impact of steaming on these profiles. Using a combination of enzymatic, gravimetric and chromatographic methods, fructans, total dietary fibre (TDF), low- and high-molecular-weight soluble dietary fibre (SDF), and insoluble dietary fibre (IDF) were analysed. Results show that the DF content varies considerably among the 29 investigated vegetable varieties and species, but the influence of steaming is limited to a shift from IDF to high-molecular-weight SDF for 18 of the 29 tested vegetables, while fructans are preserved with not actual reduction in the DP.

Keywords:

• Steaming
• fructan
• insoluble dietary fibre
• soluble dietary fibre
• vegetable

Acknowledgements

The authors express their gratitude to the farmers who contributed to provide samples for the study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was co-funded by the Walloon Government (Namur, Belgium) and Liège University in the frame work of the FOOD4GUT excellence research project.