European University of Lefke (EUL) Faculty of Agricultural Sciences and Technologies Faculty Members Asst. Prof. Dr. İbrahim Kahramanoğlu, our faculty member from the same faculty, Asst. Prof. Dr. Serhat Usanmaz’s article titled “Light: Alternative Physical Method Against Fungus-Originated Post-Harvest Rotes in Citrus Fruits”, which they co-authored with Chinese academics Dr. Jinyin Chen, Prof. Dr. Chunpeng Wan, Prof. Dr. Chuying Chen, Dr. Muhammad Farrukh Nisar and was published in the journal of Food Quality.
Giving information about the publication, Kahramanoğlu stated that the starting point of the research was “the possible effects of light on covid-19”, which was discussed much in the scientific world during the pandemic. In this context, Kahramanoğlu stated that they did not conduct a research on covid-19 because they did not have their field of expertise, but based on this discussion, they revealed that light has very important effects on post-harvest fruit preservation; Penicillium digitatum) and blue mold (Penicillium italicum) and the results obtained revealed that different wavelengths of light have different effects on fruits and fungi.
Citrus fruits are one of the most important fruits in human nutrition.
“Citrus fruits (orange, golden ball, lemon, lime, mandarins), a member of the Rutaceae family, have a production area of approximately 9.7 million hectares (29 times the TRNC) in 140 different countries according to 2018 FAO (United Nations Food and Agriculture Organization) data. and with 138.5 million tons of products, it ranks first among the most produced fruits. ”Kahramanoğlu stated that citrus fruits, which are among the most important export products of our country, have a significant impact on the world economy as well as on human nutrition. Kahramanoğlu said, “Millions of people work in the production, harvest, preservation, transportation, processing and marketing stages of citrus fruits and a significant amount of money changes hands. One of the most valuable properties of citrus fruits that make them important for human beings is their high vitamin (especially C), mineral and antioxidant properties, and the other is a very wide area of use (fruit, fruit juice, food industry, medicine making, cosmetics, etc.). But besides all these beneficial properties, citrus fruits are very susceptible to microbial pathogens (diseases) as a result of their high water content and biochemistry. “Various studies reveal that post-harvest losses in citrus fruits can be over 50%, and that the main drivers of this are green mold (Penicillium digitatum) and blue mold (Penicillium italicum).” Kahramanoğlu stated that the fact that half of the products produced using so much labor, natural resources (water, soil, etc.) and money cannot be marketed is an important problem not only for those who do this work, but for the whole world.
Agricultural chemicals are losing their acceptability
In his statement, Kahramanoğlu stated that agricultural chemicals (fungicides) are the most preferred method by producers and businesses to prevent post-harvest losses caused by diseases, and when the size of post-harvest losses caused by diseases is considered, chemicals that give successful results are controlled and registered in the light of scientific data. He stated that there is no harm in using it correctly, whereas wrong applications cause both chemical residue and resistance in diseases. Kahramanoğlu said, “In recent years, it seems that the acceptability of the chemicals used not only in citrus conservation but also in other agricultural activities has decreased by the consumers due to various negative effects detected. One of the most important consequences of this has been the reduction of the maximum acceptable residue levels (ARL) in foods. As a result, the world of science has turned to alternative methods, especially since the early 2000s. Numerous scientific studies conducted so far have revealed that hot water, hot air, vegetable oil, plant extract, edible film, various salts, plant-derived secondary compounds, nanomaterials and light have important effects in preventing post-harvest losses, as well as widely known methods. However, all of these methods are effective when applied at certain doses and durations, as in agricultural chemicals, and these doses also differ significantly between species, ”he said.
The light protects the fruits in two ways
Kahramanoğlu evaluated the effects of the light mentioned in the article;
“The light of the sun is accepted by scientists as the source of life on earth. The sun’s light radiation flowing into space warms our planet and plays fundamental roles in many chemical, biochemical and physical processes, including photosynthesis, the most well-known. The entire range of light is called the electromagnetic spectrum, ranging from long radio waves to gamma () rays. Energy and wavelength are known to have an inverse relationship, where the energy increases as the wavelength decreases. The spectrum of light visible to the human eye is only a small fraction. The right side of the visible spectrum is generally not dangerous due to its low energy, while the left side of the visible spectrum (ultraviolet “UV” rays, X rays and gamma rays) is classified as harmful to many living organisms because of its extremely high energy, ”says Kahramanoğlu, but the majority of this spectrum is visible. The light is absorbed by the atmosphere (primarily CO2, H2O and O3) and does not reach our world, with the exception of some infrared and ultraviolet light, as well as microwaves and radio light. Kahramanoğlu said that they examined the role of different light spectrums in food preservation under separate headings. These mechanisms, which are described in detail in the article, are basically divided into two groups, and the first of them is that the light activates some enzymes in fruits and makes them resistant to diseases. The second method stated that light has the property of directly targeting diseases and damaging cell structures.
Stating that he believes that the article, which compiles all these features, the benefits and possible damages of light, will shed light on other scientists and researchers, Kahramanoğlu also stated that he expects the widespread use of industrial systems where light will be used in fungus control in the near future.