Effects of Sodium Citrate on Almond Proteins for Almond-Based Beverage Products
Open Access
- Author:
- Bodinger, Leah
- Area of Honors:
- Food Science
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Federico Miguel Harte, Thesis Supervisor
Federico Miguel Harte, Thesis Honors Advisor
Chris Sigler, Faculty Reader - Keywords:
- plant-based
viscosity
fluorescence
protein structure
quaternary structure
absorbance
tryptophan residues
amandin
almond protein
almond milk - Abstract:
- High protein plant-based beverages are not inherently stable and require the addition of stabilizers and emulsifiers to ensure that proteins and other components do not settle out of solution, thus improving product acceptability. Emulsifying salts such as sodium citrate, potassium citrate, and dipotassium phosphate are added to dairy products to cause the dissociation of protein quaternary structures, improving product stability and functionality. The plant-based alternative industry’s $22.6 billion value will double by 2040, causing research in this area to become increasingly important. A Continuous Monitoring Unit (CMU) was designed to monitor the effects of increasing concentrations of sodium citrate and temperatures on the turbidity and rheological properties of reconstituted and filtered almond protein dispersions. The CMU simultaneously measured changes in the solution’s pressure, fluorescence, and absorbance values with increasing temperatures. Additionally, SDS-PAGE gel electrophoresis was used to analyze and identify protein subunits. Increasing the salt concentration from 0.1-100 mM was found to disrupt the quaternary structure of the almond protein, as higher concentrations of some protein subunits were present, but the type of protein changed. As seen via electrophoresis, the appearance of low molecular weight subunits decreased, while higher weight subunits became twice as pronounced. This trend was not as prominent with other parameters, as viscosity and fluorescence each changed by less than 0.5% throughout the series of salt concentrations. While the type of protein aggregate present in solution changed with increasing concentrations of sodium citrate, its effect on protein functionality, such as foaming and emulsification, remains unknown. As almond based beverages continue to rise in popularity, this work begins to fill the current gaps in knowledge within the plant-based food space but leaves further questions.