Effect of pulsed electric field processing on reduction of sulfamethazine residue content in milk

Efficient and safe removal of free and casein-bound oxytetracycline from milk via pulsed electric field

Oxytetracycline (OTC) residues in milk spontaneously bind to casein, forming casein-OTC complexes that complicate their removal. This study assessed the degradation effect of pulsed electric field (PEF) treatment on OTC, with a particular focus on its protein-bound form. Casein-bound OTC was successfully prepared, and the effectiveness of PEF in removing casein-bound antibiotics was confirmed using DESI-MSI technology. Under optimal treatment conditions, the degradation rates of OTC in casein-free whey (86.30 % - 93.43 %) and milk (82.47 % - 90.31 %) showed no significant difference, further confirming that the removal efficacy of PEF on OTC was unaffected by casein binding. The degradation of OTC in both matrices followed the Hülsheger model. Four major degradation products were identified, involving three distinct pathways: epimerization, demethylation, and deamidation. Furthermore, cytotoxicity assays demonstrated that PEF treatment significantly reduced the overall toxicity of OTC in milk. This study provides an effective and safe strategy for removing OTC residues from milk.

Ultrasonic treatment influences the compactness of quinoa protein microstructure and improves the structural integrity of quinoa protein at the interfaces of high internal phase emulsion

For native quinoa protein with a loose disordered structure and low structural integrity, once the protein is absorbed to the oil-water interface, the stress of interfacial tension and hydrophobic interaction can easily trigger the conformation change and denaturation of quinoa protein, leading to the instability of high internal phase emulsion (HIPE). Ultrasonic treatment can induce the refolding and self-assembling of quinoa protein microstructure, which is expected to frustrate the disruption of protein microstructure. The particle size, tertiary structure, and secondary structure of quinoa protein isolate particle (QPI) were investigated by multi-spectroscopic technology. The study demonstrates that QPIs prepared with ultrasonic treatment of 5 kJ/mL exhibit more robust structural integrity compared with native QPIs. The relatively loose structure (random coil, 28.15 ± 1.06 %∼25.10 ± 0.28 %) transformed to a more ordered and compact form (α-helix, 5.65 ± 0.07 %∼6.80 ± 0.28 %). Through the addition of QPI-based HIPE as an alternative for commercial shortening, the specific volume of white bread was increased (2.74 ± 0.35 ∼ 3.58 ± 0.04 cm³/g).

Advances in pulsed electric stimuli as a physical method for treating liquid foods

There is a need for alternative technologies that can deliver safe and nutritious foods at lower costs as compared to conventional processes. Pulsed electric field (PEF) technology has been utilised for a plethora of different applications in the life and physical sciences, such as gene/drug delivery in medicine and extraction of bioactive compounds in food science and technology. PEF technology for treating liquid foods involves engineering principles to develop the equipment, and quantitative biochemistry and microbiology techniques to validate the process. There are numerous challenges to address for its application in liquid foods such as the 5-log pathogen reduction target in food safety, maintaining the food quality, and scale up of this physical approach for industrial integration. Here, we present the engineering principles associated with pulsed electric fields, related inactivation models of microorganisms, electroporation and electropermeabilization theory, to increase the quality and safety of liquid foods; including water, milk, beer, wine, fruit juices, cider, and liquid eggs. Ultimately, we discuss the outlook of the field and emphasise research gaps.