Certified Food Safety Center, Inc.

A pulsed electric field is very high intensity variable electric field through which the food is passed. It is the predominant non-thermal process in use today for acid-based fluids, or fruit juices. Combined with mild heating, it enhances the effectiveness of microbial inactivation and extends shelf life of foods. The pathogens are destroyed through destruction of the cell membranes. Tests have shown anywhere from a five- to nine-log reduction.

Ultraviolet processing involves the use of radiation from the ultraviolet region of the electromagnetic spectrum for purposes of disinfection. Typically, the wavelength for UV processing ranges from 100 to 400 nm. The germicidal properties of UV irradiation are mainly due to DNA mutations induced through absorption of UV light by DNA molecules. UV may be used in combination with other alternative processing technologies, including various powerful oxidizing agents such as ozone and hydrogen peroxide. UV applications include disinfection of water supplies and food contact surfaces with microbial load reduction in fruit juices gaining more interest. UV processing has the potential to improve the safety and extend the shelf life of some juices while maintaining more of the fresh-like qualities of the cider compared to thermal processing.

Ionizing Radiation

Radiation for the treatment of food is achieved through the application of gamma rays (with Co-60 or Cesium-137 radioisotope), electron beams (high energy of up to 10 MeV), or X-rays (high energy of up to 5 MeV). Radiation principles explain how the gamma rays, e-beams and X-rays interact with matter. These interactions result in the formation of energetic electrons at random throughout the matter, which cause the formation of energetic molecular ions. These ions may be subject to electron capture and dissociation, as well as rapid rearrangement through ion-molecule reactions, or they may dissociate with time depending on the complexity of the molecular ion. Effects of radiation on matter depend on the type of the radiation and its energy level, as well as the composition, physical state, temperature and the atmospheric environment of the absorbing material. With proper application, irradiation can be an effective means of eliminating and/or reducing the microbial load and thus the foodborne diseases they induce, thereby improving the safety of many foods as well as extending their shelf life.

Cold plasma is a novel nonthermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. A wide array of cold plasma systems that operate at atmospheric pressures or in low pressure treatment chambers are under development. Reductions of greater than 5 logs can be obtained for pathogens such as Salmonella, Escherichia coli O157:H7,Listeria monocytogenes, and Staphylococcus aureus. Effective treatment times can range from 120 s to as little as 3 s, depending on the food treated and the processing conditions. Key limitations for cold plasma are the relatively early state of technology development, the variety and complexity of the necessary equipment, and the largely unexplored impacts of cold plasma treatment on the sensory and nutritional qualities of treated foods.

Supercritical carbon dioxide (SCCO₂) has been found to be a valuable technology for processing and preservation of fruit and vegetables. It has been employed for the inactivation of microorganisms and enzymes in fruit and vegetable products such as juices, purees, and smoothies. SCCO₂ is also an effective and green technology for the extraction of bioactive compounds (carotenoids, flavonoids, phenols, etc.) from fruit and vegetables, owing to the relatively low temperature used and the production of extracts without organic solvents.