Technique uses ozone gas to increase the quality and safety of corn

Researchers from Embrapa Food Agroindustry (RJ) validated a post-harvest technology that reduces fungi and mycotoxins in corn grains with the application of ozone gas. The technique does not affect the chemical, technological and sensorial quality of the food, with the advantage of being immediately implemented by the industrial production sector. Clean and sustainable technology also does not harm the environment, and can be used in silos for storing cereals and other types of food, including organic ones. The result is a reduction in the microbial load and an increase in the shelf life of food. Derived from more than 20 years of research, the technology is simple and easy to apply, and can be used to decontaminate various types of grains and nuts.

Ozone is recognized as a safe substance for use as a food sanitizer by the Food and Drug Administration (FDA), United States health surveillance agency. In recent years, there has been a growing interest in the application of this element in food processing, due to its effectiveness at low concentrations, short contact time and its decomposition into non-toxic by-products.

Ozone in, chlorine out

Its use in food sanitation represents an alternative to traditional chlorine-based treatment. “Ozone has a high oxidizing power, can be applied in gaseous form or in aqueous solution and is easy to obtain due to its low production cost. When used in food, it barely changes the chemical and sensory characteristics, which is why it is an advantageous alternative for the food industry”, explains Embrapa researcher Otniel Freitas, leader of the project that evaluated the use of ozone in grain decontamination.

The use of physical, chemical or biological treatments in an attempt to remove or destroy mycotoxins in grains has resulted, in most cases, in making the food unviable for consumption. Unlike these methods, the technology developed at Embrapa consists of treatment for decontaminating fungi and mycotoxins in corn grains using gaseous ozone. The application of ozone performs microbiological decontamination and the degradation of waste and contaminants, as it instantly bursts the cell walls of microorganisms. “Chemically, ozone breaks the double bonds of the oxygen molecule and neutralizes the toxic effects resulting from this reaction, disaggregating and causing a structural change in the harmful agent molecule”, explains Freitas.

Health risk and trade barrier Due to the potential risk to human health due to their toxicity, the levels of aflatoxins and other mycotoxins began to be monitored by an increasing number of countries, which began to regulate their maximum permitted limits in various food and feed products. Especially in Brazil, the presence of mycotoxins is a recurring complication in agro-industrial grain storage complexes, representing a serious food quality and safety problem. Its occurrence is controlled by legislation from the National Health Surveillance Agency (Anvisa). According to the Rapid Alert System for Food and Animal Food (Rasff) of the European Union, mycotoxins are part of the danger category with the highest number of notifications in foods. Brazilian agricultural products have been facing technical barriers abroad because they contain mycotoxins above the maximum established limits.

Health risk and trade barrier

Due to the potential risk to human health due to their toxicity, the levels of aflatoxins and other mycotoxins began to be monitored by an increasing number of countries, which began to regulate their maximum permitted limits in various food and feed products. Especially in Brazil, the presence of mycotoxins is a recurring complication in agro-industrial grain storage complexes, representing a serious food quality and safety problem. Its occurrence is controlled by legislation from the National Health Surveillance Agency (Anvisa). According to the Rapid Alert System for Food and Animal Food (Rasff) of the European Union, mycotoxins are part of the danger category with the highest number of notifications in foods. Brazilian agricultural products have been facing technical barriers abroad because they contain mycotoxins above the maximum established limits.

The application of ozone in food

In the research led by Embrapa researchers, the effects of different gaseous and aqueous ozonation conditions on the reduction of fungi and mycotoxins in corn were evaluated. Gaseous ozonation showed reductions of up to 57% in aflatoxin levels (B1, B2, G1 and G2) and a reduction in total fungal counts. The technology is simple, easy to apply, derived from a lot of knowledge gained in recent decades and cutting-edge research, and can be used to decontaminate various grains such as corn and rice, or even some oilseeds such as Brazil nuts.

For corn grains, the results obtained demonstrated that gaseous ozonation is an effective technology to reduce mycotoxin contamination. “The most drastic ozonation treatments, that is, those with higher ozone concentration, longer exposure time and lower grain mass, showed better results in reducing contamination by total aflatoxins, reaching values ​​close to 45%”, reveals Yuri Porto , who developed the research for his master's degree in Food Science and Technology at the Federal Rural University of Rio de Janeiro (UFRRJ) under the guidance of Embrapa researchers José Ascheri and Otniel  Freitas. However, Freitas emphasizes the need to correctly adopt safety procedures for the proper application of ozone in order to avoid damage to operators/analysts and also to the environment. “A safe physical structure must be maintained capable of monitoring and controlling gas emissions to avoid overexposure to ozone gas. Employees must use personal protective equipment (PPE) such as: masks, lab coats, boots and appropriate gloves”, recommends the researcher.

Diagnosis of corn contamination by mycotoxins

After ozonation treatment in corn, to evaluate the effects on mycotoxin concentrations, the samples were analyzed using a multi-analytical method developed by the team at the Waste and Contaminants Laboratory at Embrapa Agroindústria de Alimentos. This multiple analysis approach simultaneously determines thirteen mycotoxins in corn such as aflatoxins, fumonisins, ochratoxins and other Fusarium mycotoxins by ultra-performance liquid chromatography coupled to sequential mass spectrometry (CLUE-MS/MS). These toxins are food contaminants that cause harm to consumers' health and are still the main obstacles (technical barriers) for Brazilian agricultural products abroad.

“The development and improvement of analytical methods for the determination of mycotoxins in foods must be constant, in order to adapt them to the requirements of routine analysis, and mainly to meet the restrictive maximum tolerated limits (LMT) in the regulations for controlling these toxins”, says Izabela Castro, Embrapa researcher and leader of the Waste and Contaminants Laboratory team, formed by analysts Marianna dos Anjos and Alessandra Teixeira.

The method developed by Embrapa proved to be more accurate, safer and evaluates a range of mycotoxins at once, unlike the option available on the market. It can be used to evaluate the level of decontamination of corn after ozonation. The application of ozone with equipment called ozonizers popularized its use in the field of food science and technology. Currently, the main applications are as a sanitizer in the processing of fresh fruits and vegetables, fish, cheeses, juices and cereals.

Contamination in corn According to data from the Brazilian Association of Corn Industries, this cereal is considered one of the country's main crops. In 2017, around 87 million tons of grains were produced, third place in the world ranking. According to researcher Jamilton Pereira dos Santos, from Embrapa Corn and Sorghum (MG), corn is one of the most widely spread and cultivated crops in Brazil, as it adapts to different ecosystems. Throughout the national territory, around 12 million hectares account for approximately 98% of national production, in areas concentrated in the states of Mato Grosso, Mato Grosso do Sul, Goiás, Minas Gerais, São Paulo, Paraná, Santa Catarina and Rio Grande southern. Mycotoxin mitigation strategies in corn and other grains are based on prevention in the field, using good agricultural practices and cultivating resistant varieties. Post-harvest, depending on storage conditions and variations in humidity and temperature, there is a proliferation of fungi and mycotoxins resulting from their metabolism in the grains. There is a strict relationship between fungi and grains. Thus, fungi have an ecological action on grains, as they favor their germination. “Even if the grain contains mycotoxins, it is necessary to keep them at acceptable levels for human health”, ponders researcher Izabela Castro. For her, investments are needed to decontaminate grains stored not only in food, but also in animal feed, since corn is one of the main components of livestock feed. This is because mycotoxins are highly resistant, stable and, at high levels, can cause cancer and other diseases in animals and humans.

Contamination in corn

According to data from the Brazilian Association of Corn Industries, this cereal is considered one of the country's main crops. In 2017, around 87 million tons of grains were produced, third place in the world ranking. According to researcher Jamilton Pereira dos Santos, from Embrapa Corn and Sorghum (MG), corn is one of the most widely spread and cultivated crops in Brazil, as it adapts to different ecosystems. Throughout the national territory, around 12 million hectares account for approximately 98% of national production, in areas concentrated in the states of Mato Grosso, Mato Grosso do Sul, Goiás, Minas Gerais, São Paulo, Paraná, Santa Catarina and Rio Grande southern.

Mycotoxin mitigation strategies in corn and other grains are based on prevention in the field, using good agricultural practices and cultivating resistant varieties. Post-harvest, depending on storage conditions and variations in humidity and temperature, there is a proliferation of fungi and mycotoxins resulting from their metabolism in the grains.

There is a strict relationship between fungi and grains. Thus, fungi have an ecological action on grains, as they favor their germination. “Even if the grain contains mycotoxins, it is necessary to keep them at acceptable levels for human health”, ponders researcher Izabela Castro. For her, investments are needed to decontaminate grains stored not only in food, but also in animal feed, since corn is one of the main components of livestock feed. This is because mycotoxins are highly resistant, stable and, at high levels, can cause cancer and other diseases in animals and humans.