Food

Productivity

      According to the United Nations Food and Agriculture Organization (FAO), the world population will reach 9.7 billion in 2050 [4] while the current population of our planet is 7.3 billion; This growth of more than 30 % in a period of just 30 years implies that by then we will need feed more t 2.5 billion people more than at present.

Desinfección de semillas de Quinoa con plasma atmosférico frío en ION BIOTEC.

      This increase in the global need for food would require a significant increase in production. In addition, it will be necessary to increase the durability of perishable products and to fight against different pests that threaten crops. The European Commission published in 2017 a list of high priority pests against which urgent solutions are needed as they threaten both crops, forests and wooded areas of great importance [5].

        The cold atmospheric plasma technology has is able to reduce the germination time of previously treated seeds and to enhance the growth of the plant, thus increasing the productivity of fields and reducing the times between harvests [6, 7]. Multiple studies have demonstrated this plasma ability to promote germination, increase the size of leaves and seedlings and improve the productivity of different seeds including tomatoes [8], soybeans [9], corn [10], and wheat [1114].

        Different scientific studies show that the effect of plasma on germination and growth mechanisms attributable to a number of factors:

Activation of seeds from its dormancy period

       Some of the plasma reactive species, such as nitric oxide, can produce the interruption of latency period and induce germination [15].

Erosion of the seed surface

       The germination process of certain seeds require their harder outer layer to be scratched or cut so that moisture can reach inside. Some studies reveal that microerosion produced by plasma treatment in the outermost layer of the seed could be responsible for a better penetration of moisture [16, 17].

Increased surface wettability

        Plasma treatment produces changes in the surface of the seed that increase wettability. This allows water to spread through it more easily and results in an increase in water absorption capacity, favoring seed growth with less irrigation [18, 19]. This effect is especially important in areas with limited water resources.

Disinfection

       Cold plasma treatment kills harmful microorganisms such as bacteria and fungi. Seeds treated with plasma will therefore be less likely to suffer from microbial diseases that are frequent causes of large economic losses.

Food preservation

     Phenomena such as globalization and depopulation of rural areas make the transportation of food throughout the world a growing need. The distance between producers and consumers, as well as the change in consumption habits, requires the storage of food for longer periods of time and increases the need for better preservation methods. For years, high temperature treatments have been widely used for this purpose and very well accepted by consumers. However, they have certain disadvantages such as the loss of nutrients or the considerable reduction in the organoleptic properties [20]. All this motivated a growing interest in cold atmospheric plasma treatment as an alternative.

      The technology developed and patented by ION BIOTEC is so respectful with the food properties that it can be used on fresh products such as meet, fish or eggs. A few seconds are enough to reduce in 4 Log (from 6 to 2) the number of La tecnología desarrollada y patentada por ION BIOTEC es tan respetuosa con las propiedades del los alimentos que puede usarse con alimentos frescos como carnes, pescados o huevos entre otros. En pocos segundos es posible reducir en 4 Log (de 6 a 2) the number of colony forming units of aerobic bacteria present in the eggshell.

     The cold atmospheric plasma treatment has multiple advantages that highlight it as a promising alternative to traditional treatments:

Operation at room temperature

Cold plasma treatment does not transfer heat to food, which is particularly interesting in relation to heat sensitive aliments such as meat, fish, eggs or fresh vegetables [29].

Short treatment times

[21]           It has been observed that very short treatments (between a few seconds and two minutes) can produce reductions of up to 5 log in populations of different microorganisms such as Salmonella Typhimurium, S. Enteritidis, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, Campylobacter coli, Aeromonas hydrophila, Bacillus cereus and Clostridium botulinum [20, 2228].

Already packaged food treatment

       Cold plasma can be generated inside the packaging so that the food is left in an already disinfected atmosphere until it is consumed [2931].

          The effect of plasma on food preservation is the result of microorganisms inactivation on the aliments surface. Experts agree that the reactive species present in the plasma are responsible of causing damage to various structures and components of microorganisms, including cell membranes, DNA and proteins [25, 32, 33]. These damages can be divided into two categories:

Damage to the bacterial membrane

 

   The mechanical and oxidative stress that occurs on the membrane of the bacteria when they are in contact with plasma have been pointed out by several authors as the main cause of death of these microorganisms during the treatment [34-36]. This membrane stress may be due to the impact of ions and electrons present in the plasma [37] or due to changes in the amount of electrical charges on certain areas of the cell surface [38]. In addition, membrane stress facilitates the loss of intracellular material and the massive entry reactive species present in the plasma that can cause damage on structures such as DNA and thus induce bacterial death. Plasma reactive species, such as oxygen, peroxide and hydroxide radicals, metastable oxygen or ozone, are responsible of oxidative stress to bacteria that, if their damage repair capacity is exceeded, leads to his death [39].

 

Intracellular damage

   Reactive species, such as monoatomic oxygen, hydrogen peroxide, nitric oxide and excited molecules and atoms, can easily diffuse inside cells and, even with the membrane intact, oxidize many macromolecules [40, 41]. Once inside the cell, these reactive species cause damage to lipids, proteins, nucleic acids and carbohydrates [20]. The microorganisms have mechanisms to neutralize the oxidizing species and to repair the damage; however, after a particular concentration of these species is reached, the bacteria suffer oxidative stress that induces the expression of certain genes and triggers a defensive response in the microorganisms [42]. When a critical concentration is reached, the damage is irreversible and death occurs. The necessary treatment times to trigger this process last between several seconds and a few minutes.

Mycotoxin elimination

       In addition to the food natural degradation processes, the presence of molds and, in particular, the fungal toxins (mycotoxins) that some of them produce, poses a high risk for both human and animal consumers [43]. Mycotoxins, as explained by Spanish Agency for Food Safety and Nutrition (AECOSAN), are substances produced by several hundred species of molds that can grow on food under certain conditions of humidity and temperature. These are chemical substances that are generated as a byproduct of some species of fungi metabolism. The generation of mycotoxins depends on multiple factors, such as the type of food, the humidity or the temperature. Mycotoxins can be generated during cultivation, harvesting and storage.

AECOSAN also warns that

“once present in the food can’t be eliminated, since they resist drying, milling or processing processes and do not usually disappear even if food is cooked”

       These mycotoxins enter the food chain normally through contaminated crops, mainly cereals, for food and feed and they ‘are a growing global concern, rendering almost 25% of all food produced unfit for human or animal consumption, thus placing immense pressure on the food supply chain’ according to the European Commission [44, 45]. Furthermore, global warming caused by climate change is producing more regions with optimal temperatures for the growth of the fungi that produce mycotoxins and this will exacerbate the problem [46].

          AECOSAN highlights, among the possible adverse effects of the consumption of mycotoxin contaminated food, the induction of cancer and mutagenicity, as well as gastrointestinal, kidney or estrogen metabolism problems. Some mycotoxins are also immunosuppressive, reducing resistance to infectious diseases. There are mycotoxins that produce these toxic effects by long term exposure and others that also have acute (mainly gastrointestinal) effects, such as deoxinivalenol.

            In 1960, researchers pointed to mycotoxins as the cause of the intoxication of thousands of people in the United Kingdom [47]. Since then, more than 300 types of mycotoxins have been identified and the search for methods that can eliminate them has intensified. Some heat treatments have given partial results, but many mycotoxins are able to withstand high temperatures [48]. Concern about the presence of these substances and their effects on health has led the European Union to issue directives, such as the 1881/2006 or the 2002/32 , that establish limitations on the amounts of mycotoxins that are acceptable in products intended for both human and animal feed. In recent years, cold atmospheric plasma has attracted worldwide attention as a possible solution to this problem [49]. Several research projects point to this type of plasmas as a tool to degrade these fungal toxins from the surface of food and deactivate many of the organisms that produce them without leaving residues [50-53]European Commission claims that

“cold plasma at atmospheric pressure represents a promising, low-cost and environmentally friendly means to degrade mycotoxins with negligible effect on the quality of food products”

The use of atmospheric plasma addresses the problem in two ways:

Fungal growth inhibition

      Plasma is capable of generating oxidative stress in fungal cells, produces folds in its membrane and increases its permeability, resulting in a loss of cell content and the subsequent death of the cell [54, 55]. In addition, various studies show that treatment inactivates spores thus preventing fungal reproduction [56-58].

Degradation of mycotoxins

        Multiple studies show the ability of plasma to break down mycotoxins [49, 5964]. The effectiveness of plasma treatment in the degradation of mycotoxins in other non-toxic by-products depends on the characteristics of the plasma itself [65] and the treatment time [66]; but also on the type of mycotoxin [56], on the species that produces it [58] and on the substrate on which it is found [67].

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