Plant protein nanofibrils : characterising properties for future foodHerneke, Anja
This thesis explores the potential of protein nanofibrils (PNFs) as an ingredient to generate structure in food. Proteins from whey and from plants were used to form PNFs, with particular focus on proteins extracted from plants. PNFs were formed by heating (85-90 °C) the proteins at pH 2 for 24-96 h. Various microstructural features were observed on casting whey-based PNFs with nanoscale variations (length, morphology) into films. Length of the PNFs, rather than morphology, had the greatest effect on microstructural attributes. Whey is a well-studied food protein with good ability to form PNFs. Whey-based and plant-based PNFs were compared to understand better how plant proteins can be used to form PNFs with similar length. Characterisation of the secondary structure and morphology of PNFs made from plant-based sources, such as legumes, cereals, oilseeds and tubers, showed that all proteins could form PNFs, but with some variation in morphology (curved/straight). Analysis of extracted protein size and purity to investigate their effects on formation of PNFs revealed that smaller and purer proteins gave better PNFs production. Increased pH after fibril formation affected PNF morphology and the viscosity of fibrillated samples of fava bean, fava bean globular fractions 11S and 7S, and mung bean. Straight PNFs from fava beans and curved PNFs from mung beans were examined for their ability to form and stabilise foams. At relatively low concentrations, fibrillated proteins (independent of PNF morphology) generated more voluminous and more stable foam than the corresponding protein at the same concentration. At very low concentrations, only curved PNFs gave stable foams at pH close to the isoelectric point of the protein. Preliminary results indicated that curved PNFs from mung beans can also be assembled into microfibres with the help of a flow-focusing method, which has potential for use in creating meat-like textures in future food applications.
Keywordsamyloids; fava bean; mung bean; lupin; oat; rapeseed; vicilin; legumin; secondary structure; nanostructure
Published inActa Universitatis Agriculturae Sueciae
2022, number: 2022:44
ISBN: 978-91-7760-963-6, eISBN: 978-91-7760-964-3
Publisher: Swedish University of Agricultural Sciences