Physiological and biochemical responses of green and red perilla to LED-based light.

BACKGROUND: Light-emitting diodes (LEDs) are widely used in closed-type plant production systems to improve biomass and accumulate bioactive compounds in plants. Perilla has been commonly used as herbal medicine because of its health-promoting effects. This study aimed to investigate the physiological and biochemical responses of green and red perilla under various visible-light spectra. RESULTS: Results showed that red (R) LEDs improved fresh weights of shoots and roots, plant height, internode length, node number and leaf area, as well as photosynthetic rate of green and red perilla plants compared to blue (B) LEDs and RB combined LEDs. Meanwhile, B resulted in higher stomatal conductance, transpiration rate and Fv/Fm compared to R. Supplementation of green (G) and far-red (FR) did not enhance perilla growth. Reduction or absence of B decreased leaf thickness, adaxial and abaxial epidermis, and palisade and spongy mesophyll. Total phenolic content, antioxidant capacity, rosmarinic acid content and caffeic acid content of green perilla were higher under R, R8B2 and RGB + FR, while greater values were obtained in red perilla under R. Accumulation of perillaldehyde, luteolin and apigenin presented different trends from those of rosmarinic and caffeic acids in both cultivars. CONCLUSIONS: Growth and accumulation of bioactive compounds in green perilla were greater than in red perilla under similar light quality, and R LEDs or a higher R ratio in combination treatments were suitable for cultivating high-quality green and red perilla plants in closed-type plant factories. © 2020 Society of Chemical Industry.

Comparison of radiation-induced hydrocarbons for the identification of irradiated perilla and sesame seeds of different origins.

BACKGROUND: Perilla and sesame seeds, a rich source of energy, are commonly utilized in different forms in many countries. During the post-harvest period, they are contaminated with insects as well as microbes that may have importance for keeping quality and quarantine, and thus they can be treated with ionizing radiation for insect disinfestation and microbial decontamination. Reliable and routine methods to identify whether or not a food has been irradiated are needed to help consumers' understanding of irradiated food and promote international trade. In the present study, fat-derived hydrocarbons from irradiated perilla seeds and sesame seeds of Korean and Chinese origin were analyzed in order to identify irradiation treatment by comparing their properties during the post-irradiation period. RESULTS: Gas chromatographic-mass spectrometric analysis showed that several saturated hydrocarbons, such as tetradecane, pentadecane, hexadecane and heptadecane, were found in the non-irradiated control samples, while four radiation-induced unsaturated hydrocarbons (R(2) = 0.647-0.997), such as 1,7,10-hexadecatriene (C(16:3)), 1,7-hexadecadiene (C(16:2)), 6,9-heptadecadiene (C(17:2)) and 8-heptadecene (C(17:1)), were detected in all irradiated samples at 0.5 kGy or higher, with variations according to sample and origin. Concentrations of all hydrocarbons were reduced during storage and could not be detected in 0.5 kGy irradiated Chinese sample of either seed after 8 months. CONCLUSION: Radiation-induced hydrocarbons (C(16:3, 16:2, 17:2, 17:1)) could be used as markers to identify irradiated perilla and sesame seeds of both Korean and Chinese origin at 1 kGy or higher for 8 months' storage at room temperature.

An electron spin resonance study of dry vegetables before and after irradiation.

The ESR signals were successfully observed for the first time in dry vegetables (DVs) that are prominently used in oriental cuisines. We analyzed ESR signals of DV before and after irradiation. Before irradiation, the ESR signal of DV consisted of the three components: a singlet at g=2.0030, the sextet signals from Mn(2+) ion, and a singlet from Fe(3+). The first originated from a carbon centered organic free radical. The second is attributable to the sextet signal with hyperfine interactions of Mn(2+) ion centered at g=2.0020. The third is a singlet at g=4.0030 due to Fe(3+). After the gamma-ray irradiation, a new pair of signals, or twin peaks, appeared in the ESR spectrum of DV. The intensity of the organic free radical at g=2.0030 of the irradiated DV increased lineally with radiation doses. Progressive saturation behavior of the DV indicates a unique saturation and the signals obeyed various relaxation processes.