Effect of homogenization method and emulsion composition on the physical properties of faba bean protein composite films
Date
2024-12-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
The overarching goal of this research was to investigate the effect of homogenization method (high speed vs high pressure homogenization) and emulsion composition [i.e., oil content (0-15%) and methylcellulose presence vs. absence (MC; 0 vs. 1% w/w protein basis)] on the functional properties of faba bean protein isolate films. Film forming emulsions were found to be slightly shear thinning. Coarse emulsions were prepared using a high speed (HS) homogenizer and showed higher viscosities (~2x higher) and larger droplet sizes (D3,2 ~10x larger) relative to nanoemulsions which were produced using a high-pressure valve homogenizer (HP). Once cast, tensile and puncture testing indicated a plasticizing effect in HS homogenized samples where films containing oil became weaker and better able to elongate upon stretching. There appeared to be only minor differences in water vapor permeability for canola oil and MC contents; however, values for films produced using HP homogenization were slightly lower. HP homogenization resulted in films becoming lighter as oil was added, whereas HS homogenization resulted in an opposite trend. During swelling experiments, HS prepared films took on ~1100-1500% of their original weight in water, whereas films prepared using HP disintegrated too rapidly when emersed in water to accurately measure. Confocal microscopy of the dried films homogenized with HS homogenization showed large polydisperse droplets with some level of creaming prior to film setting while HP homogenized films showed much smaller and more stable oil droplets when examined with confocal microscopy. HS homogenized films containing oil demonstrated a greasy texture whereas HP homogenized films did not. In conclusion, films produced using HP homogenization tended to be stronger, showed less water vapor permeability, disintegrated readily when emersed in water and demonstrated better emulsion stability. These results indicate that HP homogenization shows potential to improve film appearance and may be more optimally suited to oral delivery applications whereas HS homogenization is a more rapid and economical method of film formation and still shows good tensile properties and slightly better integrity upon moisture uptake, a trait which may be better suited for packaging applications.
Description
Keywords
Emulsion-based film, Faba bean protein isolate, Nanoemulsion
Citation
Degree
Master of Science (M.Sc.)
Department
Food and Bioproduct Sciences
Program
Food Science