As water becomes drinkable
Introduction
Water content is a very important factor on which coligative and texture properties depend, it also greatly influences chemical, physical and enzymatic reactions. Water is divided into linked water that is the water available for the growth of microorganisms and on the other hand we have the linked water is linked to the surface and therefore is not available. Then the water activity which we understand as the partial steam pressure of the water in a substance. Therefore only water activity is capable of generating changes in food since it is available. This will somehow help us predict the stability and life of a food, at less water activity a food will be preserved much better to this is known as perishable food and therefore we will have drier and crispy foods with a high lifeof shelf;But if you have a water activity close to one, the food is considered as perishable therefore will have a smaller shelf life, these are the most tender and juicy foods.
Water activity is highly related to food texture and therefore with the proliferation of pathogenic microorganisms. And this is because in shape the water activity decreases the texture becomes hard and the food tends to dry;Foods with low water activity are a bit more crispy and break easily. But if this will increase the food too much to be softened and cease to be attractive in addition to that this is a perfect environment for the growth of microorganisms.
This is very important because it is a determining factor for food safety and will allow us to determine its conservation capacity in addition to the propagation capacity of microorganisms.
The stability of food can be classified as stable, semi -stable and unstable;The stable contains less than 12% water, the semi -stable contains between 12 and 60% water and its duration is medium and finally the unstable which contains more 60% water and tends to last little.
Acides together with water activity are two factors that are handled properly are the basis for better preserving food;since to preserve food for longer.
If we have water activity values equal to 0.98 is not viable for food conservation since it allows the growth of pathogenic microorganisms;Within these we find foods such as meat, fresh fish, fresh fruits or vegetables etc.
With values of 0.93-0.98 It really happens almost the same as with the previous one since it is also a favorable environment for the growth of microorganisms;Some foods are fermented sausages, meat products, short maturation cheeses etc.
As for values of 0.85-0.93 The growth of microorganisms is no longer favorable but there are still many possibilities that there are them.
For values of 0.60-0.85 Bacteria no longer has the means to grow and develop however there are microorganisms that are resistant to these media called osmòfilos or halophiles. Within this range we find foods such as nuts, cereals, jams or cured cheeses.
Finally food that has a water activity less than 0.60 in which there is no microbial growth, however there could be microorganisms as residents for very long periods of time;Foods with this characteristic can find chocolates, honey, cookies or sweets;This may also be due to the high sugar content present in food.
It is important to control food activity since this is very helpful for example in industries to extend your useful life. For the most perishable food, conservation techniques such as evaporation and drying are used will depend on the type of food that will be used;It can be dried by sprinkler, vacuum drying or freezing.
As we had mentioned a way to reduce water activity in food is through the incorporation of sugar or salt in order to catch water molecules.
Highlight the importance of water in food processing, as well as technological uses in the food industry.
Identify the amount of water that is present in the food, in addition to identifying the way it is found to know its behavior on the food.
Identify the hypothetical areas of water and what are their effects on food to extend the useful life of the same.
Developing
Humidity
Water is an omnipresent element in all foods, so it is necessary to identify its physicochemical characteristics, however, these are not always the same, this will depend on the state in which the water is. The determination of water content is the most frequent analysis in the laboratories of the food industry. However, depending on the analysis method, it is not the same type of moisture content, which is measured. Even the term moisture is questionable since this could include other liquids apart from water (Isengard, 1995).
Water Activity (AW)
Water activity is defined as the partial steam pressure of water in a divided substance on the partial steam of pure water. In the case of food, no type of food can present an AW = 1, since, if this happens, it would be talking about pure water.
In some cases the AW water activity is used as a synonym for free water, however, this is something wrong. Free water in a food refers to the amount of water present in food which has not changed its physicochemical properties;This means the water that is not interacting with other food components, therefore, AW and free water are very similar parameters, but they are not the same.
Sorption isotherms
It is very important for an food industry to know the moisture content of a food, as well as knowing if it is available for certain microbial enzymatic reactions or if they are in some way interacting with other constituent solutes of food and therefore the water activityIt is the one who determines the changes in food. This in order for their products to be long lasting and they have a greater benefit.
On the other hand, the isotherm of a food is the relationship between its moisture content and the water activity of it when both are in equilibrium and at a constant temperature. These are important for the analysis and design of several processes such as the dehydration and study of food drying kinetics are also useful for food mixing and to predict possible changes in their stability and a long shelf life.
For example for the production of foods such as infusions or aromatic hervates which some providing colors and aromas characteristic then with an isotherm.
Another example is the packaging material in which the appropriate components must be selected for the preparation of the containers and this will depend largely on the food capacity to gain or lose water and this knowing the isotherm of the food and its behavior is observedRegarding the permeability of the material on water vapor and other gases.
Isotherms in addition to serving for mentioned above help us to know important aspects in food processing areas such as drying, mixing, packaging and storage;since these are responsible for predicting the changes produced in the food during their processing or storage, mainly those that are related to the moisture or water activity content of the same. And this is very useful for industries since it reduces costs for losses in processes, packaging, transport and storage of the same.
Water structure and food preservation
Extending the useful life of a food product is to prevent its degradation by biochemical reactions or by the growth of microorganisms. Degradation prevention consists in reducing water availability for degradation reactions. This is achieved through reinforcing the hydrogen bond in the water and in the same way reduce its mobility.
In the inhibition of organism growth, the aim of reducing water activity (AW) is aimed, since as water activity was previously mentioned, it is decisive in the growth of microorganisms in food, as well as with most of the majority ofdegradation reactions, some of the ways to reduce water activity is the aggregation of solutes, although it is not the only parameter with which water activity is reduced.
In the same way the availability of water and its mobility for the reactions that could occur in the food depend on the type of interaction that water has.
Chemical and enzymatic reactions:
Oxidative changes:
While water can have antioxidant and prooxidant effects, this will depend on water activity;In the case of a low water activity, it can act as an antioxidant by:
While water can have antioxidant and prooxidant effects, this will depend on water activity;In the case of a low water activity, it can act as an antioxidant by:
- Metal ion hydration
- H-EDLACE OF HYDROOPEROXIDES
- Promoting free radical recombination
- In the same way you can act as a prooxidant to a high water activity by:
- The plasticizing effect favoring mobility
- Matrix swelling, exposing new surfaces.
While antioxidant effects affect more products of animal origin, they also matter in plant foods (fruits, vegetables) where the oxidative laundering of carotene and lycopene can alter the organoleptic properties of products.
One of the reactions that lead to a relationship with the water activity is Maillard’s reaction, in which the browning relates the rate of the reaction to water activity.
In various experiments a maximum browning in products has been observed where the activity is 0.3 – 0.7, however, in systems where there is a low water activity which is not associated with the strong increase in viscosity, a model based on ethylene glycol, a maximum is not obtained and the speed of the reaction continually decreases from a declineWater activity at high. In the most recent investigations there is an accepted interpretation for the Maillard reaction curve, where the low humidity interval, the rate is limited by the resistance to diffusion, which causes a decrease in the mobility of the reactants andReaction products.
The role of water activity in fruit ingredients and compound food vegetables.
The use of fruits and pieces of fruits are mostly used as basic materials or as additional components in many food formulations. In which the water activity of the ingredients must be controlled to prevent moisture from migrous components. As shown in the sig. Figure water activity in the 0 range.6 – 1 are required according to the type of food.
When fruits are used as ingredients, water activity is reduced/controlled by dehydration, although it is not the only method by which water activity can be controlled or reduced, one of these methods is an osmotic treatment, aggregationWater soluble solutes.
Technologically the combination of the thermodynamic effect of solutes in the reduction of water activity and the kinetic effect of water content can allow texture control in a range of water activity.
Proteins and water
In the same way, water is the most abundant compound in muscle fibers (muscle) ranging from 70-80% which will depend on the type of animal species, the type of muscle and the age of the "animal". During the processing of the meat, water is lost, either by dripping, evaporation or cooking. Which is a problem since in the processing of meat there is aimwater generates discontent and displeasure to consumers due to several factors:
- Driping around the meat, which generates a dislike for the consumer.
- Size reduction during different cooking processes.
- In the same way a loss in its organoleptic characteristics such as tenderness or juiciness, making the meat less attractive to the public.
Most of the water found in the muscles is in the form of free water, while the rest is linked to proteins. The muscle ability to retain the natural water content that it has is known as the water retention capacity, this represents an important parameter in the comparison of different raw materials, as well as for the prediction of in the disorption of water.
The different water loss profiles affect the enzymatic activity, is the case of proteolysis, which consists of a group of enzymatic reactions that degrade myofibrillar proteins and affect the texture. In this way, peptide and peptidase proteolysis reactions release small -sized peptides and free amino acids, which are of the utmost importance for flavor, although they also affect the smell as a result of more chemical reactions.
In this way, a method to increase water retention capacity in meat products (meat or fish) is the addition of salts, as is the case of NaCl, thus being the basis for curing and emulsified. In this process, chloride ions bind to the protein, which exerts a repulsion force between the filaments causing a swelling in the product in the same way a reduction in the available water for the growth of microorganisms.
In general, the correct processing of the meat is of the utmost importance since the content in meat or fish will determine the sensory properties, as well as an improvement in food quality.
Low water activity is a barrier for the growth of vegetative forms of pathogenic bacteria such as salmonella, studies have been done in which the thermorestrity of native salmonella strains in dehydrated and pasteurized egg albumin are very important to verify what are theoptimal and safe conditions for the treatment of this type of food bacteria. All this based on product water activity which will go hand in hand with thermal treatment to avoid the proliferation of microorganisms and thus our foods have a greater shelf life.
Salmonella does not grow below a 0 water activity value.85 That is why it is important to control its proliferation since this can be adapted rapidly to extreme desiccation conditions. Some researchers think that the formation of filamentous forms and showed that by reducing the water activity, the morphology of the salmonella cells that were eligued and made filaments were affected when incubated in media with water activity of 0.94-0.95 to 25ºC for 6 days. Then when combining the lack of water available and the application of heat in the egg albumin can provide an optimal combination of conditions to produce salmonella. That is why these factors should be greatly taken.
Some investigations in which thermorence, as well as the control of water activity in different samples of albumin of industrial eggs determined that the thermal resistance of the Salmonella strains if it depends extremely on the water activity.
Conclusions:
Water activity is a very important parameter in the food industry, through this you can determine “the useful life” of food, in addition to being within government regulations. This will greatly help losses during the process and therefore to avoid additional production expenses. Also control this parameter will also help a better transport of these and a good storage.
In addition to serving for quality regulations, this is a very necessary parameter to determine in food, since it has a great influence on food stability, as well as its physical and chemical characteristics of the same.
As already mentioned in the writing, water activity in a food will always be of great importance, every food will have water as the main component, and it is important to identify how this water is located, either as linked water or waterfree, since this will depend largely the final characteristics of food.
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