Pulsed electric fields offer safer pasteurization for colostrum
image: Overview of the three experimental trials conducted in this study.
Credit: Food Innovation and Advances
A research team demonstrated that pulsed electric field (PEF) processing can effectively inactivate harmful foodborne bacteria in bovine colostrum while potentially preserving its valuable immune-supporting compounds. By combining mild pre-heating with controlled electric pulses, the technology achieved significant microbial reductions comparable to traditional pasteurization but with far less thermal damage.
Colostrum—the first milk produced by mammals after birth—is widely recognized for its rich nutritional and immunological properties. Compared with regular milk, bovine colostrum contains higher concentrations of proteins, fats, and antibodies, particularly immunoglobulin G (IgG), which plays a crucial role in immune defense. However, to ensure safety for human consumption, colostrum must undergo pasteurization to eliminate pathogenic microorganisms. Conventional heat-based pasteurization methods can degrade sensitive proteins such as IgG, reducing their bioactivity and limiting the health benefits of colostrum-derived products. These challenges have motivated researchers to explore alternative non-thermal processing technologies capable of ensuring microbial safety while preserving bioactive compounds.
A study (DOI: 10.48130/fia-0026-0001) published in Food Innovation and Advances on 31 January 2026 by Phil Bremer's & Indrawati Oey's team, University of Otago, demonstrates that pulsed electric field processing can significantly reduce bacterial contamination in colostrum while minimizing heat-induced damage to its functional components.
To evaluate the feasibility of PEF as an alternative pasteurization technique, the researchers conducted a series of experiments examining microbial inactivation in bovine colostrum under different treatment conditions. The first phase investigated the effect of PEF on naturally occurring microorganisms in early-stage (within 48 hours after birth) and late-stage colostrum. Samples were pre-heated to 40–45 °C before being exposed to continuous-flow PEF treatment at electric field strengths of approximately 13 kV/cm and specific energies between 229 and 287 kJ/L. Following treatment, microbial counts were measured using plate count assays. The results showed that combining mild pre-heating with PEF treatment produced nearly a five-log reduction in bacterial populations, and increasing the pre-heating temperature to 45 °C enabled reductions exceeding five logs. This level of microbial inactivation is comparable to conventional pasteurization standards. In the second phase, the researchers evaluated PEF efficacy against surrogate non-pathogenic microorganisms commonly used to represent foodborne pathogens, including Escherichia coli ATCC 25922 and Listeria innocua. Colostrum samples were inoculated with these bacteria and treated using PEF at approximately 11 kV/cm with specific energy around 209 kJ/L after pre-heating to 40 °C. The treatment produced more than a 6.5-log reduction in E. coli populations and over a 5-log reduction in L. innocua, demonstrating strong antimicrobial effects comparable to thermal pasteurization. These results indicated that PEF could efficiently inactivate both Gram-negative and Gram-positive bacteria, although Gram-positive species generally exhibited greater resistance due to structural differences in their cell walls. In the final experimental stage, the team tested pathogenic bacterial cocktails consisting of multiple strains of E. coli and Listeria monocytogenes. Because of biosafety concerns, these trials were conducted in batch-mode PEF treatments using sealed cuvettes rather than continuous-flow systems. At electric field strengths near 8 kV/cm and specific energies up to 184 kJ/kg, the treatment achieved approximately a four-log reduction in pathogenic E. coli populations and about a 2.4-log reduction in L. monocytogenes. Additional experiments examined whether bacteria experienced sub-lethal injury after treatment by comparing microbial counts immediately after processing and after seven days of refrigerated storage. The results suggested that most reductions were due to bacterial inactivation rather than reversible cellular damage.
Overall, the findings indicate that pulsed electric field processing is a promising non-thermal alternative to conventional pasteurization for bovine colostrum. By combining mild heat with electric pulses, the technology can achieve substantial microbial reductions while potentially preserving sensitive bioactive molecules.
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References
DOI
Original Source URL
https://doi.org/10.48130/fia-0026-0001
Funding information
This work was funded by NIG Nutritionals and Callaghan Innovation.
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Food is essential to life and relevant to human health. The rapidly increasing global population presents a major challenge to supply abundant, safe, and healthy food into the future. The open access journal Food Innovation and Advances (e-ISSN 2836-774X), published by Maximum Academic Press in association with China Agricultural University, Zhejiang University and Shenyang Agricultural University, publishes high-quality research results related to innovations and advances in food science and technology. The journal will strive to contribute to food sustainability in the present and future.