Microorganisms in Food
Since ancient times, man has been constantly looking for innovative methods to preserve his food for a longer time.
It was in 1862 when the French biologist Louis Pasteur first experimented with the food pasteurization process. With this innovative technique it was possible to reduce the number of pathogenic microorganisms in particular foods, improving at the same time their food safety and prolonging their conservation.
Symptoms vary according to the type and extent of the disease but are generally characterized by disorders of gastrointestinal origin such as nausea, diarrhea and abdominal pain associated in the most severe cases with fever and neurological alterations.
On the appearance of symptoms that may lead to suspicion of an eating disease, it is advisable to promptly contact your doctor or the nearest emergency room, especially if children or elderly people suffer from it.
Not all microorganisms present in food are pathogenic. Some, like the "saprophytes", simply tend to alter the organoleptic characteristics of the food, others are neutral and others even perform a "favorable action like the live lactic ferments present in yogurt.
In some cases the multiplication of pathogenic microorganisms does not alter the characteristics of the food which, despite contamination, has the same appearance, flavor and consistency. The conservation of the organoleptic characteristics is therefore not a sufficient condition to exclude a possible infection of the food.
Some bacteria are able to withstand extreme environmental conditions by entering a state of temporary quiescence. As soon as the characteristics favorable to their development are restored, the proliferative processes calmly resume.
The human immune system is able to oppose possible infections with an effectiveness that depends on the type and quantity of bacteria introduced with food. Particularly at risk of infection are therefore debilitated people (stress, pathologies, etc.), children and the elderly.
The extent and damage caused by the infection are generally dose dependent; that is, they depend on the quantity of contaminated food ingested. Also in this respect there are significant differences between the various microorganisms and, while some require high bacterial loads, others require very small quantities of infected food (eg Botox) to cause the disease.
Insights
Food diseases and minimum cooking temperature
The main functions of cooking are two: on the one hand, the increase in the digestibility of food and on the other, the elimination of pathogenic microorganisms.
Both of these characteristics are in close correlation with the cooking temperature and time. If foods are cooked too little there is a risk that some viruses and bacteria will survive, if they are cooked too long they can become toxic due to the formation of carcinogenic substances.
Each food requires different preparation times and methods, for which a maximum and minimum cooking temperature is established.
Minimum cooking temperature is defined as the temperature value below which there is a risk that some of the bacteria present in the food will survive. It may also happen that at the time of consumption the food has already been contaminated by toxic metabolites produced by bacteria: toxins.
Types of Food Diseases
There are therefore three types of food diseases that can be contracted by consuming inadequately cooked foods:
- food infection: arises following the consumption of food contaminated with pathogenic bacteria. Once in the intestine, these microorganisms colonize it, multiplying and causing injury to the tissues. The higher the number of bacteria ingested, the greater the risk that the immune system will not be able to cope with the infection.
- food poisoning: arises following the consumption of foods containing toxins of bacterial origin. It is therefore not the bacterium that directly causes the infection but the toxic substance it produces. Some food diseases in fact arise due to toxins whose producer bacterium is already dead at the moment of consumption.
- food poisoning: derives from the simultaneous presence of pathogenic microorganisms and toxins. Once in the intestine, the bacterial load proliferates releasing toxins that are harmful to the organism.
Although the ideal temperature range for the development of pathogenic microorganisms varies according to the microbial species, it is generally between 5 and 60 ° C.
If on the one hand the cold is not able to eliminate the bacteria but only to delay or block their development, on the other hand temperatures above 70 ° C are generally sufficient to eradicate them completely. This is the case, for example, of salmonella or fearsome H5N1 virus present in the meat of infected birds that caused much discussion in the winter of 2005-2006: both are completely destroyed by careful cooking which consequently eliminates any risk of contagion.
CONTINUE: Second part "
