title: Aggregation of egg white proteins with pulsed electric fields and thermal processes.
abstract: BACKGROUND
  Pulsed electric field (PEF) processing is progressing towards application for liquid egg to ensure microbial safety. However, it usually causes protein aggregation, and the mechanism is still unclear. In this study, egg white protein was applied to investigate the changes in protein structure and mechanism of aggregates formation and a comparison was made with thermal treatment.
  
  
  RESULTS
  Soluble protein content decreased with the increase of turbidity after both treatments. Fluorescence intensity and free sulfhydryl content were increased after being treated at 70 °C for 4 min. Less-remarkable changes of hydrophobicity were observed after PEF treatments (30 kV cm(-1) , 800 µs). Soluble and insoluble aggregates were observed by thermal treatment, and disulfide bonds were the main binding forces. The main components of insoluble aggregates formed by thermal treatment were ovotransferrin (30.58%), lysozyme (18.47%) and ovalbumin (14.20%). While only insoluble aggregates were detected during PEF processes, which consists of ovotransferrin (11.86%), lysozyme (21.11%) and ovalbumin (31.07%). Electrostatic interaction played a very important role in the aggregates formation.
  
  
  CONCLUSIONS
  PEF had a minor impact on the structure of egg white protein. PEF had insignificant influence on heat-sensitive protein, indicating that PEF has potential in processing food with high biological activity and heat sensitive properties. © 2015 Society of Chemical Industry.
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, No. 1800, Lihu Road, Wuxi, 214122, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wu
authors.affiliation: School of Food Science and Technology, Jiangnan University, No. 1800, Lihu Road, Wuxi, 214122, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.affiliation: School of Food Science and Technology, Jiangnan University, No. 1800, Lihu Road, Wuxi, 214122, China.
authors.forename: Ruijin
authors.initials: R
authors.lastname: Yang
authors.affiliation: School of Internet of Things Engineering, Jiangnan University, No. 1800, Lihu Road, Wuxi, 214122, China.
authors.forename: Wenxu
authors.initials: W
authors.lastname: Yan
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, No. 1800, Lihu Road, Wuxi, 214122, China.
authors.forename: Qianyan
authors.initials: Q
authors.lastname: Sun
mesh_terms: D003207:Conalbumin / Q000032:analysis; D004220:Disulfides / Q000737:chemistry; D004527:Egg Proteins / Q000737:chemistry*; D004560:Electricity; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology / Q000379:methods; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D009113:Muramidase / Q000032:analysis; D010047:Ovalbumin / Q000032:analysis; D066329:Protein Aggregates; D012995:Solubility; D055672:Static Electricity; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D004220:Disulfides; D004527:Egg Proteins; D066329:Protein Aggregates; D013438:Sulfhydryl Compounds; D003207:Conalbumin; D010047:Ovalbumin; D009113:Muramidase
keywords: aggregation; egg white protein; electrostatic interaction; ovotransferrin; pulsed electric field