New preservation technologies: Possibilities and limitations

A lot of research in the field of food science has focused on new preservation technologies but very few of these methods have been implemented by the food industry until now. This article describes the most intensively investigated new preservation methods with their possibilities and especially their limitations, often hampering their implementation by the food industry. Many alternative,non-thermal' treatments have been proposed with high hydrostatic pressure and pulsed electrical fields being the most investigated ones. Both techniques allow killing of vegetative microorganisms but fail until now, when applied alone, to destroy spores. New packaging systems are introduced such as modified atmosphere packaging and active packaging systems. The latter systems have until now a limited application in practice due to incompatibility with legislation, limited effectivity and thermolability of active compounds. Natural compounds, such as essential oils, chitosan, nisin or lysozyme, are investigated to replace chemical preservatives and to obtain 'green label' products. Their application is mainly hampered due to interaction of the natural compounds with food ingredients and due to changes in the organoleptical properties when introduced in a food. The application of protective cultures, able or unable to produce antimicrobial compounds such as bacteriocins are proposed to inhibit growth of unwanted microorganisms. The activity of bacteriocins is however often limited due to its narrow activity spectrum, its inactivation due to interaction with food ingredients or proteolytic action of the food, its limited diffusion in solid matrixes and the occurrence of loss of bacteriocinogenicity of the culture and of resistance of the target organisms. This overview nuances the application of the above mentioned preservation techniques and focuses on draw backs on their application by the food industry. (C) 2003 Elsevier Ltd. All rights reserved.