Enhancing radical scavenging activity of Cordyceps militaris extract by gamma irradiation

Abstract

Nowadays, irradiation treatment has been well‐known as an effective tool to eliminate the pathogenic and spoilage microorganisms existing in foods and food ingredients in order to ensure their hygiene and extend their shelf‐life. In the present study, the dried fruiting bodies of Cordyceps militaris were irradiated under gamma source at Hanoi Irradiation Center, then extracted to collect crude polysaccharides and to evaluate the effects of gamma ray on antioxidant properties and functional groups of bioactive components in the extract (CME). Our preliminary results showed the antioxidant ability of CME, which is presented by DPPH radical scavenging activity, increased with concentration and radiation dose. The concentration required to induce 50 % antioxidant activity or median inhibition concentration (IC50) of CME decreased with radiation dose, and the smallest SC50 obtained with the CME irradiated at 15 kGy. These results suggested that the antioxidant capacity of CME can be much improved by irradiation. However, gamma radiation insignificantly affected the functional groups of CME as analyzed with Fourier transform infrared (FT‐IR) spectroscopy although the intensities of some characteristic peaks were distorted by high dose radiation.