Sporogenous bacteria

Spores may be likened to the kernel of a plum, which can tolerate extreme environmental conditions and which contains the genetic material for a new and identical plum tree. The spore can tolerate frost, dehydration, chemicals and also a good deal of cooking. That means it will survive many forms of heat treatment and can germinate and give rise to bacterial growth in a product after heat treatment. The tolerance of the spore to heat varies between the different species of bacteria and being certain of killing all pathogenic bacteria requires treatment equivalent to 121oC for 3 minutes. The current trend is to use very much less heat, so as to protect nutritional content and safeguard freshness criteria like colour, taste, smell and consistency. The smaller the heating effect (combination of time and temperature) the more bacteria species and the greater the number of bacteria that will survive.
Fortunately it is only representatives of spore producers from Bacillus and Clostridium that might present a risk in heat treated food. Control of such bacteria is therefore extremely important, in terms of preventing introduction via raw materials, killing by heat treatment and inhibiting throughout the shelf life period. Some of these bacteria can produce bacterial poisons (toxins) which can lead in turn to the transmission of illness via food. The key question therefore is what is the correct heating effect in relation to raw materials quality, hygiene, chill chain and shelf life.