Currently, scientists apply thermal, chemical and radiation methods, as well as their combinations, to ensure the safety of food. NSTU NETI conducts experiments on ionising radiation of mushrooms and other products in collaboration with BINP SB RAS and Biotechnopark. One of the research tasks is to minimize the economic costs of ionizing treatment; the purpose of scientists is to preserve the taste and nutritional value as well as extend the safety of the product at a lower level of radiation.
The laboratories of BINP SB RAS and Biotechnopark were the site for NSTU NETI scientists to start experiments on ionising radiation of processed food obtained during processing of oyster mushroom in order to increase the digestibility of protein and create a system for optimizing economic costs for complex processing of mushrooms.
Radiation treatment of various types of food reduces losses during transportation and storage of fruits and vegetables, increases the shelf life of meat, fish, poultry, delays the sprouting of potatoes and other tuber crops, and preserves the quality during long-term transportation of perishable berries.
The advantage of ionising radiation is that the vital activity of microorganisms or food pests can be suppressed without affecting the food by chemical compounds, cold or heat. Unlike frozen, a product treated with an accelerated electron flow does not lose its nutritional value and can be stored for 10-15 days longer than a fresh product in a vacuum package.
"When we process food with heat or cold, we significantly reduce the amount of the biologically active components due to losses during thawing resulting from cell rupture or heat exposure, which destroys a fairly large range of vitamins. Ionising radiation of products preserves vitamins. For example, when moisture is lost during defrosting of frozen meat, the biological value of the product decreases due to the loss of minerals and water-soluble vitamins. Ionising radiation helps to avoid these losses, since during aseptic exposure, it is possible to extend the shelf life of chilled meat to 20-25 days. When other methods of ensuring microbiological safety (such as boiling, heating or freezing) are unavailable the advantages of using ionizing radiation are obvious. It is possible to reduce losses during transportation and storage of fruits and vegetables by exposing food to radiation treatment. It can increase shelf life of meat, fish and poultry, delay the sprouting of potatoes and other tuber crops, maintain the quality of perishable berries (strawberries, blueberries, raspberries, blackberries, etc.) during long-term transportation without creating any special conditions. However, at the moment there is not enough information in Russia that regulates the ionizing treatment of products from certain food groups for a specific manufacturer, " says Lada Rozhdestvenskaya, head of the Department of Technology of Food Production at NSTU NETI.
So far, scientists say that ionizing radiation is an expensive piece of technology due to its high levels of exposure. Experiments are conducted with the objective to minimize the costs and aim to preserve the desired effect (retaining nutritious benefits and flavor, extending shelf life). The main criterion of effectiveness is to correlate required shelf life which provides optimal logistical leg with minimal doses of radiation during food processing. The scientists plan to elaborate technical instruction for ionizing treatment of various food product groups given the perspective demand.
"One of the pressing problems of technological development in food sector is to increase the range of products with high consumer properties using available natural resources to the maximum. Currently, there is an increase in the mushroom production and the development of mushroom farming in Russia, particularly in Siberia. Owing to their taste and beneficial properties, mushrooms are a promising product for the processed food and catering. This is fully applicable to the oyster mushroom provided by OOO "Maslyaninskoye Lukoshko", an enterprise which uses the latest methods of mushroom cultivation and implements all necessary technical, manufacturing and microbiological safety measures. After a series of preliminary experiments and literature data studies, the task was set to research the effect of ionizing radiation on the development of consumer properties in produce, such as increased digestibility of the developed processed oyster mushrooms, as well as researching the effect of ionizing radiation on microbiological indicators of the processed oyster mushrooms plotted against time, to establish regulatory indicators, storage conditions and shelf life", says Anastasia Dril', senior lecturer, the Department of Technology of Food Production, NSTU NETI.
The experiment revealed the effect of ionizing radiation (IR) on the content of easily digestable protein, amino acids and vitamins in raw oyster mushrooms, boiled oyster mushrooms and processed oyster mushrooms, depending on the dose of IR that affects the consumer properties of the processed product (nutritional and biological value). There was an increasing trend in the content of digestible protein, amino acids and vitamins A, B, PP, and D at a radiation dose of 1 to 10 kilogray (kGy). Ionizing radiation has been established to increase the content of easily digestable protein and the biological value of oyster mushrooms as well as to extend the shelf life of the processed food.
Food in an elaborate biochemical complex of proteins, fats and different carbohydrate structures. Some foods contain long-chain protein and carbohydrate structures which are difficult or even impossible for the human body to digest without any significant losses of biologically active components. Mushroom protein is unique in a sense that it contains essential amino acids that are not present in plant-based foods. These proteins are non-digestable due to the very specific form they exist in primary products. The low-doses radiation breaks down the protein chain into easily digestable amino acids essential for the human body.
"We are solving the issue of protein digestability, it's not just about safety, it's about providing adequate nutrition and increasing biological value of food", says Lada Rozhdestvenskaya.
Today ionizing radiation is used in mass catering mainly for disinfection. This is an absolutely safe method within the allowed range (from 1 to 10 kGy): accelerated electrons can not cause radiation pollution in the induced radiation products leading to various diseases. Processes similar to those under thermal and SHF-effect occur during processing with an accelerated electron stream. No fundamentally new substances appear, therefore, there are no new threats.
The obtained results prove an increase in protein digestibility after processing oyster mushrooms with ionising radiation. The obtained experience can be useful for technologies that increase the nutritional value of a product. The product formulation and processing technology are planned to be used in industrial production of processed food or in the development of similar processed food. Scientists plan to continue experiments in 2020-2025.
"To reduce radiophobia and actively promote radiation treatment of food, we need a body of experimental evidence collected from biological objects. So this issue means that we need to find partners among biologists and clinicians," says Lada Rozhdestvenskaya.
The results of these studies should allow the domestic agricultural complex to fully take advantages of radiation technologies while ensuring the safety of their active implementation for public health.
Reference:
Food irradiation is the process of exposing food products to ionising radiation in order to destroy microorganisms, bacteria, viruses, or insects that may be present in food. This treatment is used to improve food products' safety by increasing the expiration date of the product and reducing the risk of food-borne diseases as a result.
According to the FAO UN, the loss of products owing to spoilage is approximately a third of the total 1.3 billion tons volume produced. The use of radiation technologies enjoys the increased interest and distribution for its ability to solve this problem. According to scientists, permission to irradiate more than 80 product types is operating in 69 countries and 40 of them expose radiation on a regular basis.
Notably, the irradiated products distribution among the countries of the world shows that Asia and Oceania account for 45% (including China 36%), the countries of Americas (including USA (23%), Brazil (6%) and Canada) account for 29%, Europe accounts only for 4% and the remaining 22% are distributed among other countries, where the largest suppliers are Ukraine (17%), South Africa and Israel.
46% of products treated with ionizing radiation are condiments, dried vegetables and fruits, 22% are garlic and potatoes, 20% are grains and fruits, 8% are meat and seafood, 4% are other products.
China, being the leader on this market, has 18 national standards for irradiation of 17 groups of products since 1994, South-Korea permits irradiation of 26 types of agricultural products and food, Bangladesh 18 and Indonesia 12. Between 2011 and 2015, radiation treatment was legalized in Mongolia, Malaysia, Nepal, Myanmar and EU countries.
According to the International Atomic Energy Agency (IAEA), the total amount of agricultural products and food processed with radiation worldwide is estimated at 700-800 thousand tons annually.
Currently the following powerful sources of ionizing radiation are used in industry: isotopic sources of gamma radiation based on 60Co or 137Cs radionuclides (gamma radiation sources); industrial electron accelerators generating a powerful electron beam with an energy of up to 10 MeV; industrial electron accelerators generating bremsstrahlung x-rays when an electron beam is decelerated in a heavy metal target.
“More than 220 specialized scientific and commercial centers for irradiating food have been created worldwide and irradiation service markets constitutes about $ 2 billion. Currently, the radiation technology has entered the period of commercialization and, according to experts, by 2030 this market will reach the value of 10.9 $ billion," says Lada Rozhdestvenskaya.