Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 2/15/2006
Publication Date: 4/1/2006
Citation: Qi, P.X., Cooke, P.H., Dangaran, K.L., Tomasula, P.M. 2006. Characterization of casein films made by pressurized carbon dioxide: salt effect on water solubility. 97th AOCS Ann Meeting & Expo Book of Abstracts. p. 106 Interpretive Summary: n/a
Technical Abstract: Films made from casein, precipitated from skim milk using pressurized carbon dioxide (CO2), have been shown to exhibit unique properties such as water resistance in addition to the apparent environmental benefits that the process bears. To gain insights on the dominating molecular forces that give rise to the characteristics of CO2 precipitated casein and the films derived from this casein, we studied the effect of salt (NaCl) on water solubility using electron microscopy and laser Confocal scanning microscopy. A modified Bradford assay was used to study the protein solubility of CO2CN as a function of ionic strength (NaCl concentration) in comparison to CaCN in solution and film states. The results showed that the protein solubility of CO2CN increases as a function of salt concentration in both states (solution and film); in contrast CaCN remains unchanged. Analytical ultracentrifugation was employed to provide evidence that the weight average molecular weight of CO2CN followed an exponential decrease as the ionic strength was increased compared to other caseinates. Positively and negatively stained TEM images indicated reduction in the large irregular aggregates in CO2CN at elevated salt conditions, suggesting electrostatic interactions among caseins brought about by pressurized CO2 might be a dominating force in the formation of these aggregates.