Newswise — WASHINGTON, D.C., Oct. 24, 2018 -- Electrical engineer Koichi Takaki of Japan’s Iwate University used nanosecond-long pulses of high-voltage electricity and discharge plasma -- like that found in lightning -- to promote the growth of fruits, vegetables and edible fungi and to preserve the freshness of a variety perishable foods. Takaki will describe his findings at the AVS 65th International Symposium and Exhibition, being held Oct. 21-26, 2018, in Long Beach, California. 

“We developed a compact, easy-to-use, high-voltage electrical generator that can deliver a series of extremely short-duration bursts of plasma for a set period of time,” Takaki said. “These pulsed repetitive discharges have shown great promise as the means for both enhancing the growth of agricultural plants and keeping different food products fresh during their processing.” 

Takaki and his colleagues have repeatedly demonstrated the growth-enhancing properties of plasma on a variety of fruit, vegetable and fungal foods. They use the pulsed power generator to compress electrical energy -- as much as 100 kilovolts or about 1,000 times the voltage supplied by an American wall socket -- into plasma that is fed into the water cultivating the plants. 

“For four years, we tested our system on 10 varieties of mushrooms and found it stimulated growth in eight,” Takaki said. “In some of the tests, we were able to more than double the yield.” 

In other experiments, Takaki’s team prompted growth and increased the harvest of strawberries, spinach, turnips and komatsuna (also known as Japanese mustard spinach). Takaki believes that the plasma enhances growth by several means, including improved nitrogen fixation in the cultivation water, increased release of nitrates, activation of favorable enzymes, and elevated sugar levels. 

Moreover, the researchers found that pulsed plasma treatments on plant, vegetable and marine food items enhanced food preservation by protecting them from pathogens. 

“For example, when we infect tomato plants with Ralstonia solanacearumi, a highly infectious bacterium that causes wilting, and then treat them with plasma discharge, the plants not only survive but thrive,” Takaki said. “Other experiments show that plasma deters the growth of molds and yeasts, along with several bacterial species.” 

The researchers also applied plasma to fruits, vegetables and marine foods, such as sea urchins, during storage. “We discovered that this treatment, probably as a result of ozone released during the discharges, allowed us to maintain freshness for extended periods of time,” Takaki said. 

Currently, Takaki and his colleagues are studying how repetitive pulse voltage and discharge plasma affects proteins important in metabolism and life cycle functions such as enzymes and those found in cell membranes. 

“Our goal is to use our findings to apply our plasma technology beyond agriculture into other areas such as microorganism control and medicine,” he said. 


Presentation PB+BI+PC+PS+WeA-1, “Pulsed Power Applications for Farming and Food Processing,” by Koichi Takaki, is at 2:20 p.m. PT, Wednesday, Oct. 24, 2018, in Room 104A in the Long Beach Convention Center, Long Beach, California. 



The symposium is being held Oct. 21-26, 2018, in Long Beach, California. 


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