Toward Better Understanding of Salt-Induced Hen Egg White Protein Aggregation Using Field-Flow Fractionation

Abstract

Field-flow fractionation techniques including sedimentation field-flow fractionation (SdFFF) and flow field-flow fractionation (FlFFF) were applied to investigate hen egg white protein aggregation. The thermally induced aggregation of hen egg white protein was observed at temperatures of 60 degrees C and higher. Particle size and size distribution of hen egg white protein aggregates were characterized by SdFFF to investigate parameters affecting ZnCl 2-induced aggregation of hen egg white protein. At a fixed concentration of 1.0 M ZnCl 2 and an incubation time of 15 min, the mean particle diameters of the aggregates were determined to be 0.43, 0.67, and 0.80 mum for hen egg white protein contents of 5, 6.25, and 7.5% (w/v), respectively. With the incubation time of 15 min, increasing the concentration of ZnCl 2 from 0.5 to 1.0 and to 1.5 M caused the mean particle diameter of the aggregates to grow from 0.37 to 0.42 and to 0.68 mum, respectively at 5% (w/v) hen egg white protein. Upon prolonged contact time, larger aggregates were formed. Furthermore, FlFFF was employed as a novel approach to determine the efficiency of protein utilization for aggregation. The pH values as well as ZnCl 2 and protein concentrations influenced the efficiency of protein utilization for aggregation. With the optimum condition, that is, a protein concentration higher than 2% (w/v) and a pH greater than 5, the efficiency of protein utilization was approximately 65%.

Asymmetrical flow field-flow fractionation technique for separation and characterization of biopolymers and bioparticles

“…In both cases the proteins remained negatively charged and aggregates were not formed. The results agreed with those obtained by Samontha et al [74].…”

“…The combination of several analytical techniques collectively allowed a reliable assessment of protein self-association and aggregation phenomena. Samontha et al [74] used AsFlFFF and sedimentation FFF (SdFFF) under such conditions that led to hen egg white protein aggregation. At pH > 5 with protein concentration of 2%, and ∼25 mM ZnCl 2 , AsFlFFF and SdFFF could be efficiently utilized to control the aggregate size of hen egg white protein.…”

Encapsulation of α-tocopherol in protein-based delivery particles

“…To perform salt-induced gelation of proteins, CaCl 2 and ZnCl 2 were used as they are listed as generally recognized as safe (GRAS) by the United States of America Food and Drug Administration when used in accordance with good manufacturing practice (FDA, 2008). Our earlier investigations indicated that salt-induced gelation of BLG or HEW was best achieved by CaCl 2 or ZnCl 2 , respectively (Saeseaw et al, 2006;Samontha, Nipattamanon, Shiowatana, & Siripinyanond, 2008). One might argue that aggregate formation could already be obtained by mixing BLG with a-TOC.…”

Separation and characterization of food macromolecules using field-flow fractionation: A review

“…Hen egg white aggregation induced by ZnCl 2 and/or pH has been studied by a combination of symmetrical FlFFF and sedimentation FFF (SdFFF) (Samontha, Nipattamanon, Shiowatana, & Siripinyanond, 2008). SdFFF was utilized to study the formation of aggregates and FlFFF to investigate the amount of proteins that remain non-aggregated.…”