2.1 All foods degrade at a time longer or shorter from date of manufacture or preparation, losing their initial characteristics, thus becoming unfit for consumption and even dangerous for human health and life.
Food poisoning is a condition caused by food or drink contaminated with pathogenic microorganisms such as bacteria, viruses or parasites. In summer, due to high temperatures, such microorganisms multiply very rapidly perishable foods. The increased risk of contamination is mainly caused by improper hygiene conditions, cooking, improper food storage and preservation.
The main sources of microbiological contamination are environmental factors (soil, water, air etc.), man, vegetables, animals, insects, rodents. Besides these sources, and food may be contaminated during processing, handling, storage, transport and marketing.
Children and the elderly are most frequently affected by food poisoning, but also pregnant women, people with chronic diseases and those associated with weakened immune systems are at risk.
The main symptoms occurring in food poisoning are diarrhea, nausea, vomiting and abdominal pain.
The intensity of these symptoms can vary from case to case, taking into account factors such as age, general health condition and the type of organism causing the infection.
The causes of food are causing degradation: Physical factors: * Temperature is one of the most relevant factors which influence the development of microbial. When discussing food security, then the temperature is certainly the most important factors.
- 5-60 ° C bacteria will develop, which is the optimal range where microbial activity is resumed, 100° C bacteria can be destroyed and -18° C bacteria don’t grow;

* presence of moisture - microbiological changes that occur when moisture passes the critical level; * presence of insects - as we all know that once you reach the insects carry micro-organisms into contact with food may be contaminated

Biological factors: * The microorganisms are always present unprocessed foods and include bacteria, yeasts and moulds that give undesirable changes in sensory and nutritional qualities of food (changes of flavour, smell, taste, colour, texture, consistency). * Mould and yeast are fungi. Mould can produce dangerous toxins in food, while the growth of yeasts in food affect the quality. Mould appears - in conditions of excessive humidity - in stored.
Chemical contamination - including contamination by chemicals from the environment, heavy metals, detergents or other debris that accidentally get into food during food processing, transport or packaging.
The most important agents of food poisoning are:
Salmonella, the contamination of foods are: dairy products, chicken, eggs. Salmonella infection symptoms include stomach cramps, fever, diarrhea after 12 to 72 hours after exposure. They may take between 4 and 7 days.
E Coli: beef, juice or fresh milk, fresh produce
E. coli lives in the intestines of bovine and can contaminate beef at slaughter. The bacteria can spread when sectioning. Symptoms of E. coli infection include severe abdominal cramps, diarrhea and vomiting.
2.2
Food preservation is the process of treating the food in order to maintain as long as possible a good food for consumption. Conservation is put both the flavour of food preservation, flavour, freshness, texture and the like of chemical and microbiological point of view, they are suitable for human consumption. Once the conservation process, some perishable food such as meat, fish, vegetables, which normally start to break down after a few hours or days can be eaten after a few years in a preserved condition. Conservation must prevent the effect of enzymes, microorganisms, mould, food drying, and oxidation.
Drying and dehydration. It is one of the oldest processes used by humans for food storage. The method is that microorganisms do not grow easily in environments that lack of moisture. Meats, fruits, vegetables, herbs can be placed in the sun to dry and thus will last much longer. There are some foods that through this process changes the taste much above the original such as raisins.
Salting and smoking
Generally meats and fish are preserved by these techniques but there are some varieties of cheese, such as cheese or mixed cheese is preserved through these processes. Salting and acts as antiseptic scents forbid food which attack microorganisms.
Conservation through chemical environments
There are chemicals known as food additives, which helps to destroy microorganisms and thus preserve food. Most food additives used in current use are acetic acid, sodium citrate, calcium propionate, nitrite and nitrate. Food additives consumed in excess can harm the body, therefore treated with chemical additives products should be consumed responsibly.
Freezing
Freezing, freezing is the storage of foods at temperatures above 0 ° C. This method can keep most foods from meat, fruit and vegetables, fish and ready meals to food. In the process of rapid freezing of frozen food is recommended to avoid damage nourish texture and taste. * Cooling the food at a temperature between 3 ° and 8 ° degrees causes the food to retain the qualities of a few more days * Freezing temperatures between -6 ° C and -18 ° C makes the food to be stored up to 3 months * Freezing the food at temperatures between -18 ° C and -35 ° C can lead to preservation of up to one year.