Electropriming of wheatgrass seeds using pulsed electric fields enhances antioxidant metabolism and the bioprotective capacity of wheatgrass shoots

Low-intensity pulsed electric field processing prior to germination improves in vitro digestibility of faba bean (Vicia faba L.) flour and its derived products: A case study on legume-enriched wheat bread

This study investigated the effect of low-intensity pulsed electric field (PEF) (0.3-0.7 kV/cm) and/or germination (0-72 h, 20 °C) on faba beans prior to flour- and breadmaking. PEF (0.5 and 0.7 kV/cm) had no significant effect on the germination performance of faba bean but had a positive effect on in vitro starch and protein hydrolysis of PEF-treated beans germinated for 72 h. The incorporation of flour from soaked, germinated, PEF-treated, and PEF-treated+germinated faba beans into wheat bread, at 30% mass level, improved the nutritional composition (total starch and protein contents) and protein digestibility but it reduced the specific volume and increased the density, brownness, and hardness of the bread. This finding shows for the first time that PEF-treatment (<0.7 kV/cm) of faba beans followed by germination (72 h) improved in vitro starch and protein hydrolysis of its flour and the protein digestibility at gastric phase of its enriched wheat bread.

Effect of Germination on Seed Protein Quality and Secondary Metabolites and Potential Modulation by Pulsed Electric Field Treatment

Plant-based foods are being increasingly favored to feed the ever-growing population, but these need to exhibit improved nutritional value in terms of protein quality and digestibility to be considered a useful alternative to animal-based foods. Germination is essential for plant growth and represents a viable method through which the protein quality of plants can be further improved. However, it will be a challenge to maintain efficient rates of germination in a changing climate when seeds are sown. In the context of the indoor germination of seeds for food, consumption, or processing purposes, a more efficient and sustainable process is desired. Therefore, novel techniques to facilitate seed germination are required. Pulsed electric fields (PEF) treatment of seeds results in the permeabilization of the cell membrane, allowing water to be taken up more quickly and triggering biochemical changes to the macromolecules in the seed during germination. Therefore, PEF could be a chemical-free approach to induce a stress response in seeds, leading to the production of secondary metabolites known to exert beneficial effects on human health. However, this application of PEF, though promising, requires further research to optimize its impact on the protein and bioactive compounds in germinating seeds.

Pulsed electric field treatment of seeds altered the endophytic bacterial community and promotes early growth of roots in buckwheat

BACKGROUND

Endophytic bacteria provide nutrients and stimulate systemic resistance during seed germination and plant growth and development, and their functional properties in combating various stresses make them a powerful tool in green agricultural production. In this paper we explored the function of the endophyte community in buckwheat seeds in order to provide a theoretical basis for the application and scientific research of endophytes in buckwheat cultivation. We used pulsed electric field (PEF) technology to treat buckwheat seeds, monitored the effect of high-voltage pulse treatment on buckwheat seed germination, and analyzed the diversity of endophytic bacteria in buckwheat seeds using the amplicon sequencing method.

RESULTS

PEF treatment promoted root development during buckwheat seed germination. A total of 350 Operational taxonomic units (OTUs) that were assigned into 103 genera were obtained from control and treatment groups using 16SrRNA amplicon sequencing technology. Additionally, PEF treatment also caused a significant decrease in the abundance of Actinobacteria, Proteobacteria, and Bacteroidetes. The abundance of 28 genera changed significantly as well: 11 genera were more abundant, and 17 were less abundant. The number of associated network edges was reduced from 980 to 117, the number of positive correlations decreased by 89.1%, and the number of negative correlations decreased by 86.6%.

CONCLUSION

PEF treatment promoted early root development in buckwheat and was able to alter the seed endophytic bacterial community. This study thus makes a significant contribution to the field of endophyte research and to the application of PEF technology in plant cultivation.

Unrevealing the impact of pulsed electric fields (PEF) on cucumber seed vigour and surface disinfection

Chemicals used for seed treatments help to increase the agricultural production by preventing pests and pathogens but also cause environmental and health problems. Thus, environmentally-friendly technologies need to be developed for a seed treatment that inactivates surface microflora and improves seed vigor. One such pulsed electric field (PEF) treatment applied to cucumber seeds in the range of 1.07-17.28 Joule (J) significantly enhanced a mean germination rate (MGR) by up to 9%, a normal seedling rate by 25.73%, and a resistance to 100 and 200 mM salt stresses by 96% and 91.67%, respectively, with a stronger and faster growth of roots and seedlings. PEF treatment provided 3.34 and 3.22 log-reductions in the surface microflora of total mold and yeast and total aerobic mesophilic bacteria, respectively. The electrical conductivity (EC) values of the control samples increased over time, from 4 to 24 h. Those of the PEF-treated samples after 4, 12, and 24th hours were also more affected by the measurement time not by the PEF treatment.

The joint optimization of 18 responses based on the best-fit Gaussian process model pointed to 19.78 s and 17.28 J as the optimal settings. The PEF treatment appeared to improve seed germination ability and stress resistance with the adequate inactivation of surface microflora.

An untargeted metabolomic insight into the high-pressure stress effect on the germination of wholegrain Oryza sativa L

High hydrostatic pressure (HHP) technique is used as a novel abiotic stress factor for efficiently enhancing the biosynthesis of selected bioactive phytochemicals in germinated wholegrain, but the information about HHP stress-induced metabolic changes remains rather limited. Thus, the current work employed an untargeted gas chromatography-mass spectrometry-based metabolomic approach combining with multivariate models to analyze the effect of mild HHP stress (30 MPa/5 min) on the overall metabolome shifts of wholegrain brown rice (WBR) during germination. Simultaneously, major phenolics in germinated WBR (GBR) were detected by ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, to explore the potential relationship between HHP stress-induced rice metabolome alternations and the biotransformation of bioactive components. The results demonstrated that the influence of HHP stress on GBR metabolite profiles was defined by germination durations, as revealed by the differentiation of the stressed grains from the naturally germinated grains at different germination points according to principal component analysis. This was further confirmed by the results of orthogonal projections to latent structures discriminant analysis, in which the discriminating metabolites between naturally germinated and HHP-stressed grains varied across the germination process. The metabolite signatures differentiating natural and HHP-stressed germination included glycerol-3-phosphate, monosaccharides, gamma-aminobutyric acid, 2,3-butanediol, glyceryl-glycoside, amino acids and myo-inositol. Besides, HHP stress led to the increase in ribose, arabinitol, salicylic acid, azelaic acid and gamma-aminobutyric acid, as well as the reduced phenolic acids. These results demonstrated that HHP stress before germination matched with appropriate process parameters could be used as a promising technology to tailor metabolic features of germinated products, thus exerting targeted nutrition and health implications.

Electric stimulation promotes growth, mineral uptake, and antioxidant accumulation in kale (Brassica oleracea var. acephala)

Several studies have demonstrated that electric treatment has a positive effect, respectively, on germination, root growth and post-harvest quality. Nevertheless, there is still a lack of research on the effect of electric treatment on growth characteristics and quality of whole plants. Here, we explored the effect of electric fields on two cultivars of kale (Brassica oleracea var. acephala). Three levels of electric current (10, 50, and 100 mA) were applied to the nutrient solution of hydroponically grown plants for three weeks. Kale plants subjected to the electric fields, particularly 50 mA, had higher fresh and dry weights than the control. The absence of an electric field in a Faraday cage caused a significant decrease in shoot and root growth compared with the natural electric field (control). Electrostimulation enhanced nutrient uptake by activating root hair formation and active ion transport. Plants grown under 50 mA contained 72% more calcium, 57% more total phenolic compounds, and had a 70% greater antioxidant capacity than the control. This work provides foundational information regarding the effects of electrical stimulus on plants, which could enable the development of innovative culture technologies to improve crop yields and quality.

Modelling of Carotenoids Content in Red Clover Sprouts Using Light of Different Wavelength and Pulsed Electric Field

The paper presents the results of influence the light of different wavelengths and pulsed electric fields on the content of carotenoids. Seeds germination was carried out in a climatic chamber with phytotron system. The experiment was carried out under seven growing conditions differing in light-emitting diode (LED) wavelengths and using pulsed electric fields (PEFs) with different strength applied before sowing. Cultivation of the sprouts was carried out for seven days at relative humidity 80% and 20 ± 1 °C. Different light wavelengths were used during cultivation: white light (380–780 nm), UVA (340 nm), blue (440 nm), and red (630 nm). In addition, the pulsed electric field (PEF) with three values of strength equal to 1, 2.5 and 5 kV/cm, respectively, was applied to three series of sprouts before sowing. Sprouts treated with the PEF were grown under white light (380–780 nm). The light exposure time for all experimental series of sprouts was 12/12 h (12 h light, 12 h dark for seven days). Lutein is the dominant carotenoid in germinating red clover seeds, the content of which varies from 743 mg/kg in sprouts grown in red light, 862 mg/kg in sprouts grown in UVA, to 888 mg/kg in sprouts grown in blue light. Blue light in the cultivation of red clover sprouts had the most beneficial effect on the increase of carotenoids content and amounted to 42% in β-carotene, 19% in lutein, and 14% in zeaxanthin. It confirms that modelling the content of carotenoids is possible using UVA and blue light (440 nm) during seed cultivation. An increase in the content of β-carotene and lutein in red clover sprouts was obtained in comparison to the test with white light without PEF pre-treatment, respectively by 8.5% and 6%. At the same time a 3.3% decrease in the content of zeaxanthin was observed. Therefore, it can be concluded that PEF pre-treatment may increase mainly the content of β-carotene.

Impact of pulsed electric field treatments on the growth parameters of wheat seeds and nutritional properties of their wheat plantlets juice

This study was designed to explore the impacts of the pulsed electric field (PEF; 2 to 6 kV/cm; a number of pulses 25 and 50) on wheat (Tritium aestivum L.) seeds before imbibition to improve the germination, growth, and their nutritional profile in juice form. It was observed that the PEF treatment at 6 kV/cm at 50 pulses increased water uptake, germination of seeds, and growth parameters of seedlings. A significant increase in total phenolic contents, DPPH, chlorophylls, carotenoids, soluble proteins, minerals, and amino acids in PEF-treated seeds plantlets juice as compared to the untreated seeds plantlets juice was observed. The results indicate that the PEF may effectively stimulate the growth of the wheat kernels and positively affect their metabolism, optimize the nutrients, and enhance the strength of the wheat kernels plantlets.

The Effect of Tartary Buckwheat Flavonoids in Inhibiting the Proliferation of MGC80-3 Cells during Seed Germination

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) is rich in functional compounds such as rutin, quercetin, d-chiro-inositol, dietary fiber, and essential amino acids. Electric field (EF) treatment before sprout germination results in physiological and chemical changes, and some alterations might lead to positive applications in plant seeds. MTT assay showed that the effect of total flavonoids on human gastric cancer cell line MGC80-3 was significantly changed after EF treatment for different germination days (3-7 days). Among them, the total flavonoids of tartary buckwheat (BWTF) on the third day had the most obvious inhibitory effect on MGC80-3 (p < 0.01). In addition, flow cytometry evidenced that different ratios of quercetin and rutin had effects on the proliferation of MGC80-3. The same content of quercetin and rutin had the best effect, reaching 6.18 ± 0.82%. The anti-cancer mechanism was mainly promoted by promoting the expression of apoptotic proteins. The expression of Bax/Bcl-2 and caspase-8 in MGC80-3 cells was mediated by BWTFs. This study has good research value for improving the biological and economic value of tartary buckwheat.

Sprouted Grains: A Comprehensive Review

In the last decade, there has been an increase in the use of sprouted grains in human diet and a parallel increase in the scientific literature dealing with their nutritional traits and phytochemical contents. This review examines the physiological and biochemical changes during the germination process, and the effects on final sprout composition in terms of macro- and micro-nutrients and bioactive compounds. The main factors affecting sprout composition are taken into consideration: genotype, environmental conditions experimented by the mother plant, germination conditions. In particular, the review deepens the recent knowledge on the possible elicitation factors useful for increasing the phytochemical contents. Microbiological risks and post-harvest technologies are also evaluated, and a brief summary is given of some important in vivo studies matching with the use of grain sprouts in the diet. All the species belonging to Poaceae (Gramineae) family as well as pseudocereals species are included.

Electrically induced changes in amaranth seed enzymatic activity and their effect on bioactive compounds content after germination

Electric treatment applied to seeds and sprouts can change their phytochemical composition. However, only a handful of studies have investigated the effects of treating seeds with electric current prior to their germination on the enzymatic antioxidant system of their sprouts. The aim of this study was to determine the changes in bioactive compounds and the enzymatic antioxidant activities in seeds and amaranth sprouts under direct electric current (DC) treatments. Amaranth seeds were treated with DC at 500 mA for different periods of time (0, 2, 5, 10 and 30 min) and let sprout (85% RH, 25 ± 2 °C) for 6 days. Significant changes were found in the antioxidant enzymatic activities and in the total content of flavonoids (15.44 ± 0.56 mg RE/gDW) and phenolic compounds (35.87 ± 0.17 mg GAE/gDW) in 6-day-old sprouts from DC-treated seeds in comparison to sprouts form non-treated seeds. The results suggested that DC treatment for short period (5 min) can induce quantitative changes to the enzymatic antioxidant system of amaranth sprouts, thus representing a relatively cost-effective method for enhancing health-improving properties of sprouts.