Ji F, Sun J, Sui Y, Qi X, Mao X. Microbial inactivation of milk by low intensity direct current electric field: Inactivation kinetics model and milk characterization.
Curr Res Food Sci 2022;
5:1906-1915. [PMID:
36300164 PMCID:
PMC9589170 DOI:
10.1016/j.crfs.2022.10.015]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022] Open
Abstract
Microbial inactivation by pulsed electric field (PEF) has been studied widely although with high operational risk, while few studies on the potential of low intensity electric fields for microbial inactivation have been reported. In this study, the feasibility of inactivating microorganisms in milk by low intensity direct current (DC) electric field was investigated. Then a kinetics model was proposed based on the inactivation curves. Finally, the effect of electric field on the microflora and physicochemical properties of milk was analyzed. Results showed that the bacterial reduction >5 log CFU/mL could be achieved at 50–55°C, 0.3 A–0.6 A, and with 5 min starting intensity of 5 V/cm-9 V/cm. The inactivation kinetics consisted of three stages, therein, the middle stage, main part of the inactivation curve, followed 1st-order reaction kinetics, and the effect of temperature on it was consistent with the Arrhenius Law, which implied that the electric field itself can inactivate bacteria without thermal inactivating effect. The microflora analysis showed that naturally occurring bacteria in the milk contained typical potential pathogenic bacteria (e.g., 56.9% of Acinetobacter spp.) and spoilage bacteria (e.g., 27.5% of Pseudomonas spp.), and the electric field can inactivate them. Moreover, the inactivation chemically preserved the milk's fresh-like characteristics (according to indexes of whey protein denaturation rate, furosine content), and physical stability (turbidity, zeta potential, particle size, color and so on). Therefore, a promising approach is provided for microbial inactivation in dairy industry.
Microbial inactivation of milk in low intensity direct current electric field was verified.
The bacteria (7.5 log CFU/mL) in milk were completely inactivated.
The main part, middle stage, of inactivation followed 1st-order reaction kinetics.
For Acinetobacter spp. and Pseudomonas spp., inactivation of the electric field was non-selective.
Inactivation on the physicochemical properties of milk was at an acceptable level.
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