Many types of food are spoiled by micro-organisms during storage. There are exceptions, such as food that has been tinned or has too low a water activity for microbes to grow on it, such as crispbread or sugar. Microbiological spoiling of food can change its taste, smell, consistency and appearance. Some examples of such changes are mouldy tomatoes, sour and lumpy milk, fermenting juice or rotten meat. Which micro-organisms are spoiling the food depends on many factors, such as the food's composition and the production and storage conditions.
To maintain quality through to the consumer, hygiene during production must be extremely good. There are many measures that can be taken to maintain quality during storage. For some types of food (some kinds of cured sausage and yoghurt for example) lactic acid bacteria are actively used to produce the product. Nofima Mat is researching into the optimum use of lactic acid bacteria to achieve the correct product quality, to prevent the growth of undesirable bacteria and to have a positive health effect. In some products (such as cooked ham and raw, vacuum packed meat) lactic acid bacteria could spoil the product, through the production of acid. This applies particularly to food that is vacuum packed. The shelf life of a product is also dependent on packaging technology and the packaging material in use.
Heat treatment of food doesn't just change its appearance and texture, but can also eliminate micro-organisms and increase shelf life. Nofima Mat is working on optimising heat treatment. We are also investigating the effectiveness and possibilities of using high pressure, which is a relatively new technology for increasing shelf life if heat treatment of the product is not desired.
Often the use of several micro-organism preventives (such as salt, acid, low water activity and heat treatment) in the same product can have a very good effect without the product properties being perceived as negative. In many traditional products the long shelf life is the result of using several preventive measures together. Nofima Mat combines the knowledge from these traditional products with new knowledge to help in improving products and developing new ones.
Micro-organisms can adapt and change quickly and we know from experience that they can adapt to the methods people use to control them. Nofima Mat is therefore researching into how bacteria defend themselves against the measures taken to prevent their growth and survival in food and production areas.
