Bisht AGoh KKTSims IMEdwards PJBMatia-Merino L2024-01-262024-07-252024-01-032024-01-262024-07-252024-04-01Bisht A, Goh KKT, Sims IM, Edwards PJB, Matia-Merino L. (2024). Does harvesting age matter? Changes in structure and rheology of a shear-thickening polysaccharide from Cyathea medullaris as a function of age. Carbohydrate Polymers. 329.0144-8617https://mro.massey.ac.nz/handle/10179/70556A shear-thickening polysaccharide from the New Zealand Black tree fern (Cyathea medullaris, commonly known as mamaku) extracted from different age fronds (stage 1: young, stage 2: fully grown and stage 3: old) was characterised in terms of structure and rheological properties. Constituent sugar analysis and 1H and 13C NMR revealed a repeating backbone of −4)-β-D-GlcpA-(1 → 2)-α-D-Manp-(1→, for all mamaku polysaccharide (MP) samples from different age fronds without any alterations in molecular structure. However, the molecular weight (Mw) was reduced with increasing age, from ~4.1 × 106 to ~2.1 × 106 Da from stage 1 to stage 3, respectively. This decrease in Mw (and size) consequently reduced the shear viscosity (ηs-Stage 1 > ηs-Stage 2 > ηs-Stage 3). However, the extent of shear-thickening and uniaxial extensional viscosity of MP stage 2 was greater than MP stage 1, which was attributed to a greater intermolecular interaction occurring in the former. Shear-thickening behaviour was not observed in MP stage 3.(c) 2024 The Author/sCC BY-NC-ND 4.0https://creativecommons.org/licenses/by-nc-nd/4.0/Mamaku polysaccharideShear-thickeningMolecular structureShear rheologyExtensional rheologyJournal article10.1016/j.carbpol.2023.1217571879-1344journal-article121757S0144861723012225