Biodeterioration of foods and an overview of preservation in the food and dairy industries

Most food and dairy preservation techniques act by inhibiting microbial growth: low temperature storage in frozen or chill distribution systems; lowering water activity by drying or by the addition of salts, sugars and other solutes; removing O2 and/or increasing CO2 in vacuum or modified atmosphere packages; acidification through the addition of acids or by fermentation; the addition of preservatives; control of microstructure, e.g. in water-in-oil emulsion foods. In contrast, heat is the only technique used on a large scale that acts by inactivating microorganisms. Radiation also acts via inactivation, but its use for food preservation is still minimal. However, new techniques are being applied and researched that will increase the number of inactivating techniques that are available. These include the addition of bactericidal enzymes such as lysozyme and the lactoperoxidase system, non-enzymic proteins such as lactoferrin and lactoferricin, and bacteriocins other than the already well-established ‘lantibiotic’ nisin. New physical procedures include the application of high hydrostatic pressure to ‘pressure pasteurize’ foods, the combined application of ultrasonic radiation, mild heat and slight pressurization (‘manothermosonication’), high voltage electric discharges (‘electroporation’) and high intensity laser or non-coherent light pulses. It is likely that the use of these techniques in additive or synergistic combinations will deliver the most interesting potential applications for improved preservation, quality and guarantee of safety of food and dairy products in the future.