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Description
Sterilization by electron beam irradiation offers significant advantages. In the present work, the effect of e-beam on the physicochemical properties of honey was studied. Four commercially available honey samples were irradiated with the beams of 3.5MeV electrons at dose rate 10, 20, 30, and 40 kGy using the linear pulse acceleratorat Board of Radiation and Isotope Technology (BRIT), India. The specifications of the E-beam set-up are: 250mA pulse current, 1mA average current, 10Hz pulse repetition rate, 3cm per second conveyer speed, and 5kGy dose per pass. Prior to irradiation, radiometric B3 films were appropriately placed onto the glass plates for dose monitoring. There were a total of sixteen samples which were sealed in glass bottles and subjected after irradiation to various physicochemical tests pertaining to their color, pH, refractive index, free radical scavenging activity, sugar analysis, and total phenolic counts(TPC), and compared with pristine honey samples.
The refractive index of honey (measure of the quantity of reducing sugars)was examined by a BRIX refractometer, and values were compared with the results of analysis of reducing sugars done by RP-HPLC with RI detector, to get the Fructose/Glucose (F/G) ratio. It was seen that the ratio of reducing sugars was not affected significantly by the higher doses of irradiation, and the F/G ratio remained higher than 1, which ensured that honey did not crystallize at room temperature. The pH measurements revealed a slight decrease from 10 to 40kGy,which could be attributed to radiolysis-induced increase of free amino acids.The lower pH is also expected to improve the anti-bacterial activity of honey.
The color intensity of honey is due to polyphenols, and could thus be related to the antioxidant activity. The DPPH radical scavenging assay and Folin-Ciocalteau method were carried out for the antioxidant activity and total phenolic content, respectively. It was observed that these parameters varied with dose of irradiation. Thus, the color of all honey samples darkened post irradiation and a corresponding increase was noted in the antioxidant activity and total phenolic content. In conclusion, the irradiation dose of 30kGy sufficiently improved the antioxidant activity for all samples without significantly affecting other properties. Thus, E-beam irradiation is not only useful for sterilization but also for enhancing its quality parameters.
Key Words: E-beam, Honey, HPLC, Antioxidant,DPPH,TPC.
