For product developers in the food industries, whether macro or micro industries. These industries are constantly faced with the challenges of today’s market demand, as these demands require products with a longer shelf life and simultaneously contain quality attributes (colour, flavour and nutritional content) that are reasonably priced.
It is important for product developers to scrutinize preservation methods to decrease the damaging effects of processing treatment on a food product, therefore constantly researching new technologies for food preservation. This article tends to outline the different preservation methods.
What is food preservation?
Food preservation is a process that aims to eliminate/slow down the spoilage factors to prevent food borne illness and to deem products safe for consumers, while maintaining quality attributes, by methods of treating and handling of a food product, thus from the raw material to the final product.
Blanching: The process aims to preserve colour and inhibits natural aging by inactivating the most heat resistant enzymes by boiling a food product such as fruits and vegetables.
Inert gases/ Modified atmospheric packaging: The process inhibits microbial activity by displacing oxygen or changing the ratio of oxygen in an enclosed environment causing an unfavourable environment for microorganisms to grow. The most common gases used is Nitrogen, carbon dioxide and carbon monoxide.
Freezing: The process inhibits microbial activity and enzyme activity by means of reducing the optimum temperature for microbial and enzyme activity.
Freeze drying: The process involves the freezing of a foodstuff and removing the water through sublimation, thus reducing microbial and enzyme activity.
Vacuum packaging: Most microbial activity occurs in the presence of oxygen. This process reduces the level of oxygen so that microbial activity may be inhibited. However anaerobic organisms (non oxygen tolerated) may find these conditions favourable, therefore increasing the anaerobic microbial population. It is best to utilise this process with a combination of gases and freezing methods.
Smoking: The process is commonly used in the meat industry which aims to intensify colour and flavour, and simultaneous retards fat oxidation. Smoking creates a bacteriostatic effect by the reduction of water accessibility, thus inhibiting microbial activity.
Ohmic heating: The process involves passing an electrical current through the foodstuff which renders food with quality attributes, thus flavour, colour and texture is unimpaired.
Microwave heating, Radiation, Ultraviolet light: These processes utilize radiant energies to inhibit microbial and enzyme activity. Warning: these methods should be used in
moderation to avoid radioactivity.
Ultrasound: The process utilizes an ultrasonic sound wave, which passes through a body of a foodstuff, commonly a liquid/ semi liquid and the sound wave inhibits microbial activity by the rupturing of the cell wall of the organism.
High pressure processing: Body of food stuff is passed through a chamber, it is then subjected to high pressures to rupture microbial cell walls and intern inhibits microbial growth.