Conformation and Structure of Bio Polymer Nano Particle Formed by β-Lactoglobulin-Pectin in the Presence of Sorbitol
Zahra Pishgahi
Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, P. O. Box 14515.775, Iran.
Hamid Ezzatpanah *
Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, P. O. Box 14515.775, Iran.
*Author to whom correspondence should be addressed.
Abstract
Aims: This research investigates the influences of low methoxyl pectin (LMP) and sorbitol on the morphology and secondary structure of beta-lactoglobulin (BLG).
Methodology: The effects of pH and temperature on the structure of the nano-complexes containing BLG, BLG-LMP and BLG-LMP in the presence of co-solvent (sorbitol) were studied by means of a far-UV Circular Dichroism spectroscopy (CD) and the size and morphology of nano-complexes measured by particle size analyzers, Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM).
Results: CD results at different pH levels (4, 4.5, 5.3 and 6.3) indicated that the structural changes of BLG were more pronounced relative to BLG-LMP and BLG-LMP in presence of sorbitol. However, less destruction faced the protein structure at pH 5.3 compared to pH 4.5 and 4, therefore pH 5.3 was selected. BLG-LMP in presence of sorbitol had more protective effects on the secondary structure and indicated a high thermal stability when heated up to 75ºC for 10 minutes. Particle size measurement revealed that the size of BLG aggregate was as much as 250 nm while the BLG-LMP size in presence of sorbitol nano-complex was around 100 nm. SEM and TEM observations indicated uniform and spherical nano-complexes.
Conclusion: The treated bio polymer particles have suitable properties and great potential as carriers for encapsulation and delivery of bio-active materials as well as a substitution for lipid droplets.
Keywords: Beta lactoglobulin, pectin, sorbitol, nano-complex, SEM, TEM