Content preservation of foods by drying sorption isotherm drying by heating Drying lyophilization (

Content preservation of foods by drying sorption isotherm drying by heating Drying lyophilization (sublimacion drying, kriodesikacija) Effect of drying on the quality dalda foods jobs of the food ingredients Concentrating Concentrating applying heat Concentrating Concentrating freezing water separation by membrane addition of certain compounds to reduce water activity preservation of food by adding salt Conclusion References
. People have used this principle of food preservation for ages. In practice, the accepted methods of preservation of perishable foods on this principle can be divided into three groups: drying, ie the removal of water and food to remain in the solid aggregate state. concentrating, ie removal of water to a lesser degree compared to drying. Commonly, the products are conserved concentrating the liquid aggregate state, increasing the dry matter content by adding certain dalda foods jobs amounts of substances that bind part of free water, and reduce the water activity.
Of course it is possible conserved food and a combination of these methods. Canned foods on this principle in practice is usually sufficient to achieve aw = 0.6 to 0.7 (RRV = 60-70%). Some foods, according dalda foods jobs to the specific composition, microbiological do not deteriorate even if the numerical value of water activity and higher. The jam is sufficient to achieve aw = 0.72, at the same time as it acts against osmotolerantnih yeasts and relatively high natural acidity. In some cases, to the outlet, and the enzyme activity, it is necessary to reduce the water activity of below 0.6. According to some beliefs, the enzyme activity can take place only under aw = 0.12. Often achieving a water activity below 0.6 impairs the quality of food due to the acceleration neenzimatskih and other autooksidacionih reactions dalda foods jobs (some argue that the maximum Majar reactions in the field with aw = 0.2-0.3).
The total consideration of the influence of water activity, we note that insects like to eat dried products, and that many of them live and act on dried foods, although the activity of water in the store from 0.6 to 0.5 or even less. The ability to influence microbial and nemikrobioloških factor in changing the quality of food, depending on the water activity, is shown in Figure dalda foods jobs 1
From any mode of preservation, which is based on the principle of reducing the activity of water, drying has the longest tradition. Dried foods have been known for ages. It is probably the oldest method of food preservation in general. Preservation by drying some called kseroanabiozom (from the Greek kseros = dry). The oldest methods of drying foods were based on the use of solar energy and wind. And nowadays the West African fishermen fish salted and dried in the sun. In the sun dried fruits known for centuries back, and practiced today where climatic conditions allow it. The heat that is not stimulated directly by the sun, in the United States began to be used for drying the 1900th year. Today, using modern equipment for drying, in fact mimic and enhance natural drying conditions, ie, apply the heat and airflow. Only somewhere in the middle of the last century, this method of preservation is raised to the level of technology. While drying can be conserved by any foods, usually dried fruits and vegetables (potatoes, carrots, cabbage, asparagus, mushrooms, peppers, celery, tomatoes, beans, peas, apples, apricots, figs, peaches, pears, plums, grapes etc.). In general, dalda foods jobs foods are dried so that the water in the form of water vapor separated from foods that are: be heat or freeze in the first stage, the heated gas in the second stage.
While there is no practical application at this point, dalda foods jobs the fact that foods can be dried at room temperature, ie without heating, and the application of certain desikanata (agents that absorb moisture). Since the ingredients in this case is not heating, practically does not suffer any changes, which is manifested exceptional quality. When it comes to drying, it is understood that foods before drying can be solid (plums, grapes) or liquid (milk) the physical condition, and that the final product in the solid aggregate state. dalda foods jobs Drying the separated water to the extent that such foods may years to be protected dalda foods jobs from degradation, and loss of taste plesnivljenja. In doing so, should dalda foods jobs not be deducted, amount of water because it negatively dalda foods jobs influences the flexibility (elasticity) and the ability to re-absorption of water. Most food should be dried to that equilibrium moisture content of foods that contain at 60-70% relative humidity. dalda foods jobs If the moisture content is lower, and there are no conditions to maintain the relative humidity corresponding to the equilibrium moisture dalda foods jobs content, food should be packed in packaging imprevious dalda foods jobs to water vapor. If the moisture content is higher than the equilibrium moisture content dalda foods jobs at a given relative humidity of air, foods should be stored at low temperatures, or a surface to be protected using appropriate chemical conservative