is possible that one of the main problems facing the human being was the proper storage of food raw material collected. From the earliest times as a primary concern was the need to extend the life of their food sources, who managed through systems connected to the habitat conservation in developing their lives.
During the first period were preserved food with no other basis of a simple selection of sources and stored for a short time. Scheme
historic preservation methods
conservation methods today are intended primarily to prevent deterioration of the quality of processed foods during necessary periods of storage. This quality is assessed in terms of nutrition, sensory and safety or public health.
In practice when a food raw material, more or less perishable, can not be used immediately needs a proper treatment to avoid the risk of physical alterations, chemical or biological weapons.
To prolong the life of stored food and processed products is essential to preserve them somehow.
preserved foods are those having undergone appropriate treatment seeking inactivation of pathogenic microorganisms and degrading action on food. These conditions allow the study of the feasibility for implementation of food preservation techniques and sterilization techniques should be kept in proper sanitary conditions for consumption during a period of time.
Optimizing the good stability of food materials pass through select those methodologies to exercise strict control over the "microbial population" to reduce the initial number of microorganisms and prevent or predict the development. To achieve the reduction of the initial charge just extreme hygiene outset in all manipulations. In contrast to combat the growth of microorganisms there is the alternative to choose between two types of physical and chemical methods.
NO BENEFITS thermal methods
1. Minimal changes in food quality
2. Minimal loss of flavor and nutrients
3. Flavor of "fresh"
4. Reduced energy expenditure
5. New product development
Conservation is based on a series of actions:
"Prevention or delay of bacterial decomposition: Keep food without microorganisms and eliminate existing ones.
" Prevention or delay of self-decomposition food through the destruction or inactivation of the enzymes and prevent or slow the chemical reactions.
"Prevention of deterioration due insects, higher animals, microorganisms and so on.
Overall conservation methods can be divided into two main groups: physical and chemical.
classification methods
In this first part deals with the physical preservation methods.
A. PHYSICAL METHODS
1. radiation treatments
Food irradiation is a physical process which is to expose to the direct action of electromagnetic radiation, electronic or atomic and used to improve the hygienic quality, increase their retention or modify some technological characteristics.
is being used to improve food preservation, for the destruction of microorganisms or to inhibit biochemical transformations (reactions that take place in a food and deteriorate).
is used in foods rich in polyunsaturated fatty acids can lead to peroxides
advantages:
-Food is not under the action of heat and therefore the organoleptic characteristics hardly change.
-allows the treatment of packaged foods.
"The food can be stored with a single manipulation, without specifying the use of chemical additives.
"The energy needs of the process are very low.
-nutritional losses are similar to the current preservation methods.
"The process can be controlled automatically and requires very little labor.
Disadvantages:
"The high cost of installation. "The bad marketing
Product Rating
Radiation UV: using radiation of wavelengths shorter than visible light. Are low frequency and low energy. The chemical reactions induced by this radiation can cause the arrest of metabolic reactions essential for the survival of microorganisms. This will induce changes such as broken links, which comes to preventing transcription and DNA replication.
Transcript: No microbial growth. Replicating DNA
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resistance of microorganisms and this radiation is determined by its ability to repair this damage. Radiation of this kind penetrate little in the liquid and almost nothing solid, so he used to kill microorganisms in the air or on the surface. Radiation is used both for food packaging.
Ionizing Radiation: Are high frequency radiation, which means they have a high energy content, a great power of penetration and its action is lethal.
Advantages: It is very lethal. The dose can be adjusted to give pasteurizing or sterilizing treatments, no sensory changes at low levels,
leaves no residue when little heat produced can be used in raw and frozen, instant penetration presents a uniform and profound.
Disadvantages: Are accurate: the control and protection of personnel, and the work area against radioactive sources.
2. High Pressure
consists of applying high pressure on food between 1,000 and 10,000 atm. This treatment affects many biological systems, mainly to as cell membranes, so mind is seriously compromised the survival of contaminating microorganisms. These treatments modified food components of high molecular weight, which is often a degree of protein denaturation or starch gelification. In contrast to the high pressures on food of low molecular weight shows little change as vitamins and compounds responsible for aroma and flavor. Therefore, in many cases the food maintains its nutritional value and does not differ in their sensory characteristics.
advantages: Decontamination, destruction of microorganisms, Maintenance of vitamins, aromas and flavors, new product development, product whole
Disadvantages: Cost and developing method
3. Pulsed Electric
This technique involves the inactivation of microorganimso to implement a large number of electrical pulses of short duration (microseconds) and high field strength. Not provoke increased in temperature does not alter the physicochemical characteristics of the food, nor are there significant variations in the nutritional components, but for now has only been applied to homogeneous viscous foods such as fruit juice, milk, yogurt, allowing the passage of electricity.
advantages: no loss of nutrients or sensory changes, microbial destruction without temperature increase
disadvantages: Fluids and / or small particles and Cost
4. Protective atmospheres
is a packaging system or storage Atmosphere. Is to replace the atmosphere surrounding the product with another, prepared for each type of food. The use of this technique can extend the life of food, since it inhibits the growth of microorganisms and have better control of chemical and enzymatic reactions. The gases used are: O2, N2, CO2. The effectiveness of the use of protective atmospheres is variable depending on the type of food, gas mixture, both quantitatively and qualitatively, as well as packaging material, storage temperature and used packaging equipment.
The nutritional quality of the products treated with this technique is maintained, without any loss of nutrients even vitamins. One disadvantage is that if not controlled certain conditions may appear undesirable odors and flavors. It is used to dry products, liquids, meat, soft drinks, H2O, delicatessens, some fruits and vegetables in modified atmosphere packaging.
The protective atmosphere is classified into 5 types:
packaging or modified atmosphere : Replace the atmosphere surrounding the food at the time of filling the other composed a gas or mixture of several.
controlled atmosphere container for : The food is maintained during throughout the storage period in an atmosphere of fixed composition.
permeability packaging film especially : The atmosphere surrounding the product is changed naturally due to respiration and biochemical changes of the product and the permeability of the container wall.
Vacuum Packaging: The product is packaged with a material impervious to gases and air is evacuated, then sealed the container.
hypobaric storage: Stored under pressure
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