Physicochemical and rheological properties of dietary fibres extracted from agri-food by products: Comparison against methylcellulose

Fibres from different agri-food by products have varying physicochemical and functional properties that require further investigation in the context of sustainable food production to fundamentally understand the relationship between composition, structure and function. In this study, physicochemical and rheological properties of dietary fibres (DF) extracted from nine different sources namely apple pomace, wheat straw, hemp fibres, oat hulls, oat bran, pumpkin seeds, mushrooms compost, and coffee silverskin were compared to methylcellulose. The hydration, emulsifying, structural, and rheological properties were characterised. Hemp fibre (69.63 g/100g) and apple pomace (19.52 g/100g) had the relatively highest and lowest DF contents. Onion peels dietary fibre (OPDF) exhibited the highest water binding (0.94 g/g) and swelling capacities (13.85 mL/g). Methylcellulose (MC), acid-extracted apple pomace dietary fibre (AC-APDF) had the highest water holding capacities (12.74 g/g). MC was the only sample to exhibit excellent emulsification property with no serum layer observed. All DF samples and MC exhibited shear thinning behaviours with increasing shear rates. The spectral analysis showed that all DF samples contained characteristic peaks of polysaccharides. The findings correlate with results from PCA analysis and indicate the potential of DF from onion peels and apple pomace to act as a functional ingredient in the food industry. • Fibres from different sources exhibited varying physicochemical properties. • Onion peels and apple pomace dietary fibres had the best hydration properties. • FTIR spectral analysis showed characteristic polysaccharide peaks in DF samples. • There was a correlation between DF solution viscosity and viscoelastic properties.