Pulsed Electric Field Processing of Foods

Natural flavour, colour and sufficient shelf life are some of the basic requirements of processed foods. These can be achieved by minimal processing methods that not only preserve foods but also retain to a greater extent their nutritional quality and sensory characteristics by reducing the reliance on heat as the main preservative action. The resulting products have higher quality and consumer appeal. Out of the different non-thermal processing techniques viz pulsed electric fields, high pressure processing, high intensity light and ultrasound; pulsed electric field (PEF) is one of the more promising processing methods. Inactivation of microorganisms exposed to high voltage PEFs is related to the electromechanical instability of the cell membrane. Electric field strength and treatment time are the two most important factors involved in PEF processing. When exposed to high electrical field pulses in the range of 12–35 KV/cm cell membranes develop pores either by enlargement of existing pores or by creation of new ones. These pores may be permanent or temporary depending on the condition of treatment. The pores increase membrane permeability allowing loss of cell contents or intrusion of surrounding media either of which can cause cell death. Application of PEF technology has been successfully applied for the pasteurization of foods such as juices, milk, yogurt, soups and liquid eggs. Its application is restricted to food products with no air bubbles and with low electrical conductivity and is also not suitable for solid food products that cannot be pumped. The high initial cost of setting up the PEF processing system is the major obstacle confronting those who would encourage the system's industrial application. Innovative developments in high voltage pulse technology will reduce the cost of pulse generation and will make PEF processing competitive with thermal processing methods.