Effect Of Pulsed Electric Field On Stability Of Phosphatides Dispersion System

Effects of pulsed electric field (PEF) treatments on the stability of phosphatidesdispersion were studied in this paper. Various physical and chemical properties of treatedphosphatides dispersion, concering particle size distribution, ξ-potential, surface tension,conductivity as well as the kinetics constants of coalescence，oxidative index, MDA contents,fatty acid composition and molecular conformation,were analzed by dynamic light scattering(DLS), Wilhelmy measuring plate, Zetasizer (ZS),conductivity meter, UV spectrophotometer(UV), GC, Raman spectrum (Raman). Detail research contents are as following.The results showed that the partical mean size was significantly reduced and sizedistribution of powder phosphatides shifted towards smaller size direction with the increase ofelectric field strength and number of applied pulses. The mean particle size was reduced by67%from594.4nm (contrast) to203nm at a filed intensity of70kV/cm.The surface tension value of solution with different concentration after being treateddecreased with increasing electric field strength. The absolute value of ξ-potential firstlyincreased when the filed intensity ranges from0-20kV/cm, and then decreased if the filedintensity increased further.The conductivity of solution with different concentration after being treated increasedwith increasing electric field strength while conductivity decreased with increasing keepingtime after PEF treatment.The changes of conductivity were decreased sharply between0and50min, and these change law fitted to coacervation dynamics equation. The kinetics constantsof coalescence changed with changing electric field strength and different concentration and itdecreased first and then increased at concentration of2g/L while increased with increasingelectric field strength with concentration of5g/L、10g/L.There no obvious oxidation showed from phospholipid oxidation stability and fatty acidcomposition of the phospholipid. The conformation changes of phospholipid molecular indifferent electric field strength was studied using Raman spectroscopy. The Raman spectrademonstrated that there was little influence of PEF on the conformation of O-C-C-N+backbone in the choline group of phospholipid while the gauche/trans ratio of C-C increasedafter PEF treatment. It indicated that the intermolecular disordering in hydrocarbon chain ofthe lipid lattice was increased and the membrane fluidity was enhanced after PEF treatment.