Search

Induced electric field (IEF), as an alternative non-conventional processing technique, is utilized to sterilize liquid foods. In this study, the survival and sublethal injury of S. aureus under IEF were investigated in 0.85% normal saline, and the inactivation mechanism of IEF was expounded. The plate count results showed that the sublethal injury rates remained above 90% after IEF treatment for more than 8.4 s, and 7.1 log CFU/mL of S. aureus was completely inactivated after 14 s IEF treatment. Scanning electron microscopy and transmission electron microscope images showed that IEF caused the destruction of cell membrane and internal substructure, and the damage to intracellular substructure was more severe. Altered membrane integrity or permeability was demonstrated through flow cytometry and confocal laser scanning microscope analysis, and the different damage to cells was quantified by propidium iodide & 5-carboxy fluorescein diacetate single and double staining. In addition, IEF treatment also decreased the membrane potential and esterase activity of S. aureus cells. Putative inactivation mechanism of IEF against S. aureus is a complex process, and its apoptosis is the result of the combination of several factors, which provide a basis for understanding the inactivation mechanism of IEF. [Display omitted] • Germicidal efficacy and inactivation mechanism of IEF on S. aureus were explored. • Sublethal injury rates remained above 90% after IEF treatment for more than 8.4 s. • IEF caused the destruction of cell membrane, substructure, and permeability. • IEF decreased the membrane potential and esterase activity of S. aureus cells. • Putative inactivation mechanism of IEF against S. aureus is a complex process. [ABSTRACT FROM AUTHOR]

Non-conventional heating technology based on electric fields can be utilized to process liquid foods. In this study, the induced electric field (IEF) was investigated to clarify its inactivation mechanism on E.coli. Staining results show that inactivation of E.coli by IEF can be attributed to the reversible destruction of the cell membrane, followed by the denaturation of intracellular enzymes, and finally the irreversible rupture of the cell membrane. The increased levels of extracellular proteins and nucleic acids were also observed. IEF treatment at 400 Hz and 800 V (or 53 V/cm) results in a reduction of 4.5 log CFU·mL−1 in the number of E.coli. Storage life analysis shows that IEF treatment can improve the stability of apple juice and the content of bioactive components. Thus, IEF is a potential technique for liquid food processing. • The inactivation mechanism of induced electric field on E.coli was investigated. • A reduction of 4.5 log CFU·mL−1 of E.coli was realized by applying the IEF. • IEF treatment retains bio-active components in fresh apple juice. • The storage stability of apple juice was improved through IEF treatment. [ABSTRACT FROM AUTHOR]

This study aimed to efficiently and selectively hydrolyze maize starch via induced electric field (IEF). The role of electrical conductivity in regulating hydrolysis efficiency and selectivity was investigated, and the structural and physicochemical properties of hydrolyzed products were characterized. Compared with water-bath heating, IEF induced the rapid and ordered migration of charged species, thus increasing the hydrolysis rate and narrowing the molecular weight distribution of hydrolyzed starch. The addition of KCl enhanced IEF-assisted hydrolysis due to the absorption of additional electrical energy into the reaction system. After hydrolysis, the molecular chains of maize starch exhibited cleavage, the granular surface became rough, the crystallinity increased, the gelatinization enthalpy slightly increased, the viscosity of starch paste reduced, the hardness of starch gel declined, and the re-crystallization showed no significant improvement. Overall, this study extends the potential applications of electro-techniques in preparing hydrolyzed starch with narrow molecular weight distribution in food and material fields. [Display omitted] • Induced electric field (IEF) improved the hydrolysis efficiency of maize starch. • IEF increased the hydrolysis selectivity of maize starch. • The efficiency and selectivity enhanced with the increasing conductivity. • IEF-assisted hydrolysis roughened granular surface and increased crystallinity. • IEF-assisted hydrolysis decreased viscosity but showed no effect on re-crystallization. [ABSTRACT FROM AUTHOR]