Chromatographic methods to obtain the biomolecules profile of some aromatic plants irradiated with electron beam

Irradiation is being progressively considered as a versatile and effective conservation technique [1]. Based on this premise, our research group has been investigating the effects of different irradiation conditions in several food matrices. Aromatic plants are among the food products that require suitable conservation technologies to expand their use [2]. The effects of irradiation on the four species (Aloysia citrodora, Melissa officinalis, Melittis melissophyllum and Mentha piperita) studied herein were previously evaluated. In the present study, the same species were treated with different doses of electron-beam irradiation (0, 1 and 10 kGy) and several parameters were evaluated. The individual sugars profile was determined by HPLCRI, fatty acids by GC-FID, organic acids by HPLC-PDA and tocopherols by HPLCfluorescence. In general, the evaluated parameters remained practically unchanged, regardless of plant species or the irradiation dose. Regarding the profile of sugars, the major change was a decrease in the content of disaccharides. The most notable variations in organic acids were observed in plant species with the highest content in these molecules, especially the decrease observed in the samples of M. officinalis and M. melissophyllum. Among the tocopherols, the α and β isoforms were more susceptible to radiation, while the application of 1 kGy tended to increase the levels of tocopherols in Aloysia citrodora, while 10 kGy had the same effect on M. melissophyllum. M. piperita sample showed the highest levels of tocopherols, regardless of the dose applied. Finally, with regard to the fatty acids content, the irradiated samples showed higher percentages of monounsaturated fatty acids than the control samples. In general, analyzing the results taking into account the effects described, it can be concluded that the application of irradiation with electron beam at doses 1 and 10 kGy is an effective way to retain biomolecules profile of the studied species.

Quality control of gamma irradiated dwarf mallow (Malva neglecta Wallr.) based on color, organic acids, total phenolics and antioxidant parameters

This study addresses the effects of gamma irradiation (1, 5 and 8 kGy) on color, organic acids, total phenolics, total flavonoids, and antioxidant activity of dwarf mallow (Malva neglecta Wallr.). Organic acids were analyzed by ultra fast liquid chromatography (UFLC) coupled to a photodiode array (PDA) detector. Total phenolics and flavonoids were measured by the Folin-Ciocalteu and aluminium chloride colorimetric methods, respectively. The antioxidant activity was evaluated based on the DPPH(•) scavenging activity, reducing power, β-carotene bleaching inhibition and thiobarbituric acid reactive substances (TBARS) formation inhibition. Analyses were performed in the non-irradiated and irradiated plant material, as well as in decoctions obtained from the same samples. The total amounts of organic acids and phenolics recorded in decocted extracts were always higher than those found in the plant material or hydromethanolic extracts, respectively. The DPPH(•) scavenging activity and reducing power were also higher in decocted extracts. The assayed irradiation doses affected differently the organic acids profile. The levels of total phenolics and flavonoids were lower in the hydromethanolic extracts prepared from samples irradiated at 1 kGy (dose that induced color changes) and in decocted extracts prepared from those irradiated at 8 kGy. The last samples also showed a lower antioxidant activity. In turn, irradiation at 5 kGy favored the amounts of total phenolics and flavonoids. Overall, this study contributes to the understanding of the effects of irradiation in indicators of dwarf mallow quality, and highlighted the decoctions for its antioxidant properties.