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The genus Stachys is a member of the Lamiaceae family. These are important medicinal plants which grow all over the world and are known for their flavoring and therapeutic effects and Stachys lavandulifolia is an endemic species of Iran. To acquire high‐quality essential oil (EO), drying technique was implemented which is an essential part of this process. The present study designed to evaluate the influences of different drying techniques (fresh sample, shade, sunlight, freeze‐drying, microwave, and oven‐drying (40, 60, and 80°C) on EO yield and composition of S. lavandulifolia. The results indicated that the maximum EO yield was obtained by the shade‐drying method. The main compounds found in the fresh samples were spathulenol, myrcene, β‐pinene, δ‐cadinene, and α‐muurolol, while spathulenol, cyrene, δ‐cadinene, p‐cymene, decane, α‐terpinene, β‐pinene, and intermedeol were found to be the dominant compounds in the dry samples. Drying techniques were found to have a significant impact on the values of the main compositions, for example, monoterpene hydrocarbons such as α‐pinene, β‐pinene, myrcene, and β‐phellandrene were significantly reduced by microwave drying, oven‐drying (40, 60, and 80°C), and sunlight‐drying methods. Drying techniques increased the antioxidant activity of S. lavandulifolia EOs especially those acquired by freeze‐drying with the half‐maximal inhibitory concentration (IC50) values 101.8 ± 0.8 mg/ml in DPPH assay and 315.2 ± 2.1 mg/ml in decreasing power assay. As a result, shade‐, sun‐, and oven‐drying (40°C) were found to be the most important techniques for attaining maximum yields of EO. The present study designed to evaluate the influences of different drying techniques (fresh sample, shade‐drying, sunlight‐drying, freeze‐drying, and oven‐drying (40, 60, and 80°C), and microwave‐drying) on EO yield and composition of Stachys lavandulifolia.

This experiment was conducted to evaluate the effects of different drying methods on drying parameters and qualitative characteristics of Dracocephalum kotschyi in a completely randomized design with three replications. Treatments included shade drying as control, sun drying, cabinet drying (CD at 50 and 60°C), refractance window drying (RWD), infrared drying (IRD) at 200 and 300 W, and combination of RWD+ IRD at 200 and 300 W. According to the results, IRD, RWD, and RWD+ IRD effectively maintained valuable secondary metabolites compared to the conventional drying methods. The maximum total phenol content (2.7 and 2.66 mg GAE/g dry weight), total flavonoid content (2.26 and 2.33 mg QE/g dry weight), antioxidant activity (79% and 78.33%), and essential oil content (0.65% and 0.76%) were obtained from plants dried by RWD and IRD. Samples dried by RWD, IRD, and RWD+ IRD had high color quality, acceptable green color, and less browning. Also, RWD and IRD methods effectively reduced microbial contamination of dried plants compared to the control and other methods. The minimum aerobic mesophiles, mold, yeast, and coliforms were observed at 3.11, 0, and 1.47 log CFU/g in IRD 300 W and 3.17, 1, and 1.30 log CFU/g in RWD. D. kotschyi dried at CD 50°C had the maximum microbial contamination. Generally, according to the obtained results, RWD and IRD methods are suggested for drying of D. kotschyi and similar herbs due to shortening the drying time, preserving and improving the quality properties of dried plants. The research was conducted for the first time to compare various drying methods (refractance window drying (RWD), infrared drying (IRD), and RWD+ IRD in comparison to conventional drying methods) to select the appropriate method for Dracocephalum kotschyi with an emphasis on protecting the phytochemical characteristics accompanied by reducing microbial contamination.

Dracocephalum kotschyi is a medicinal plant rich in antioxidant phytochemicals. Identifying the suitable cultivation region and evaluating the impact of environmental factors can help in choosing the best conditions for the commercial production of these herbs. The present study investigated the effect of different cultivation areas, Lasak (LSK), Saravarsu (SVS), and Sorkh Geriveh (SGV) on the glandular trichome density and phytochemicals of D. kotschyi . According to the findings, the environmental factors significantly affected the plant phytochemicals. The highest glandular trichome density (16 number mm −2 ), essential oil content and yield (0.716% and 0.45 g m −2 ), geraniol (24.3%), citral (16.2%), cis -carveol (13.2%), α-pinene (12%), methyl generate (7.2%), geranyl acetate (7.1%), PAL activity (10.104 nmol min −1 g −1 FW), total phenol (2.036 mg GAE g −1 DW), coumaric acid (0.112 mg g −1 DW), rutin (29.688 mg g −1 DW), rosmarinic acid (9.668 mg g −1 DW) and apigenin (8.089 mg g −1 DW) were recorded in the SGV region so that was up to 100-fold higher than in the LSK region. Finally, the environmental conditions of the SGV region (higher altitude, lower temperature, rainfall, and humidity, as well as some soil characteristics) strongly increased the production of phytochemicals, so this region is suggested for the commercial production of this plant and its secondary metabolites for various industries.

A two-year study has been conducted to optimize saffron cormlet production in a soilless cultivation system. Variations in the concentration of phosphate, boron, and irrigation events were assessed in the first year. Subsequently, after optimizing the substrate composition, the effects of nutrient solution volume and the concentration of nitrate, iron, and boron were investigated on the yield and weight of cormlets and leaves, photosynthetic activities, and productivity of nutrient solutions in the second year. Irrigation events in the first year significantly influenced cormlet growth, while phosphate and boron had no substantial effects. Moisture characteristics indicated an optimal substrate composition of 15% cocopeat, 15% cocochips, and 70% perlite. In the second year, increasing nutrient solution volume (225 ml/pot/week) and nitrate concentration up to 9800 µM significantly increased the weight of the leaf, total photosynthesis rate, and large-sized cormlets (> 8 g) to nearly 50% of total cormlets. Conversely, increasing iron concentration notably decreased the weight of total and large-sized cormlets. Boron concentration again showed no significant effect on the parameters. The highest nutrient solution productivity was achieved with a 150 (ml/pot/week) nutrient solution containing 9800 µM nitrogen and 25 µM iron. These findings underscore the importance of effective irrigation and nutrition management in enhancing the quantity and quality of cormlet production, potentially boosting perennial saffron yield in the following years.

Cold plasma is known as a novel nonthermal processing method for decontamination of medicinal and aromatic plants (MAPs); however, there are little research studies about its effects on active ingredients of these plants. The aim of this research was to investigate the influence of low‐pressure cold plasma (LPCP) treatments (1, 3, and 5 min) on the essential oil (EO) content and composition of lemon verbena leaves. The EO content was determined using hydro‐distillation, and the composition of the extracted EOs was quantified using gas chromatography and gas chromatography–mass spectrometry techniques. The results showed that by increasing the LPCP treatment duration, the EO content was reduced from 1.2 to 0.9 (% v/w). The highest content of monoterpene hydrocarbons (e.g., limonene) and oxygenated sesquiterpenes (e.g., spathulenol and globulol) was also observed in LPCP‐treated ones, whereas the oxygenated monoterpenes (e.g., citral) content of control was measurably higher than those treated with LCPC. Effect of cold plasma on quality of lemon verbena leaves was evaluated. By extending the LPCP treatment duration, EO content was decreased. The highest content of limonene was determined in LPCP‐treated ones.

Spearmint essential oil is a valuable medical and food product. Spearmint essential oil is effective for the treatment of flatulence, indigestion, nausea, and colic along with Alzheimer, obesity, and fungal infections. This study evaluated the quality and quantity of spearmint essential oil by examining some extraction strategies. The procedures were hydro-distillation, hydro-steam distillation, microwave-assisted hydro-distillation, and open hydro-distillation. The hydro-distillation had five pH levels (2, 4, 6, 8, and 10) and four NaCl concentrations (0.5, 1, 1.5, and 2%). microwave-assisted hydro-distillation at a power of 225 W was applied for 60, 90, and 120 minutes for process durations. The solvent extraction of herbal distillate obtained by an open hydro-distillation system was done using n-pentane and n-hexane to achieve a recovered essential oil by a rotary evaporator. The results showed that the lowest pH in the hydro-distillation process led to obtaining double yield compared to the control. Additionally, at 1 and 1.5% NaCl concentrations, the oil yield increased by 12.86 and 20.87%, respectively. Although the yield was reduced by microwave-assisted hydro-distillation, however within 120 minutes, carvone increased by 12.7% and limonene decreased by 42.3%. The best quality of spearmint oil belonged to solvent extraction followed by rotary evaporator.

Microbial quality assurance has always been an important subject in the production, trade, and consumption of medicinal and aromatic plants (MAPs). Most MAPs have therapeutic and nutritional properties due to the presence of active substances such as essential oils, flavonoids, alkaloids, etc. However, MAPs can become infected with microorganisms due to poor hygienic conditions during cultivation and postharvest processes. This problem reduces the shelf life and effective ingredients of the product. To overcome these problems, several technologies such as using ethylene oxide gas, gamma irradiation, and steam heating have been used. However, these technologies have disadvantages such as the formation of toxic by‐products, low consumer acceptance, or may have a negative effect on the quality of MAPs. This requires a need for novel decontamination technology which can effectively reduce the biological contamination and minimize the food quality losses. In recent years, new technologies such as ozonation, cold plasma, ultraviolet, infrared, microwave, radiofrequency and combination of these technologies have been developed. In this review, biological contamination of MAPs and technologies used for their decontamination were studied. Also, the mechanism of inactivation of microorganisms and the efficacy of decontamination techniques on the qualitative and microbial characteristics of MAPs were investigated. Medicinal and aromatic plants are often contaminated with biological contamination. Usage of novel technologies is different according to the type of product. Combined systems were suggested to be a promising technique for decontamination.

Kelussia odoratissima Mozaff. (Apiaceae) is a native plant that has been traditionally consumed in Iran’s food and pharmaceutical industries. Overharvesting of the taxon, especially at the beginning of the growing season, due to its considerable medicinal and economic value, is believed to be the main reason for the extirpating of this plant. The consequences of the severe anthropogenic impacts on the genetic diversity of populations are poorly known. In order to investigate the level of genetic variation and patterns of the genetic structure of K. odoratissima , we developed novel microsatellite markers using the 454 Roche next-generation sequencing (NGS) platform for the first time. Out of 1,165 microsatellite markers bioinformatically confirmed, twenty-five were tested, of which 23 were used to screen genetic variation across 12 natural populations. Our results showed that the average number of alleles per locus and the polymorphic information content (PIC) were 10.87 (range 7 to 27), and 0.81 (range 0.67 to 0.94), respectively. The mean observed and expected heterozygosities (± SD) across all populations were 0.80 ± 0.31 and 0.72 ± 0.14, respectively. The average pairwise F ST among the populations was 0.37 (range 0.04 to 0.81). Bayesian and distance-based clustering, and principal coordinate analyses revealed at least four major genetic clusters. Although high level of structure can be explained by landscape topography and geographic distance, presence of admixed populations can be associated to seed or pollen dispersal. Contrary to expectations, the high level of genetic variation and lack of inbreeding suggest that overexploitation has not yet significantly purged the allelic variability within the natural populations in protected areas.

Spearmint essential oil (SEO), one of the economically valuable natural products, has special importance in the food, pharmaceutical, and perfumery industries due to its antifungal, antioxidant, and enzyme inhibitory properties. In this study, we optimized and evaluated the effect of three pre‐treatments on the extraction of SEO for quantity and quality: ultrasonic bath (UB), water to material ratio‐ultrasonic bath (W/M‐UB), and cold plasma‐ultrasonic bath (CP‐UB). Three experiments were designed using the central composite design (CCD) of response surface methodology (RSM). Experimental treatments included UB temperature (30–80°C) and time duration (1–30 min), cold plasma (CP) power (15–24 kV), and water/material ratio (10–40). Then, SEOs were extracted by hydro‐distillation using the Clevenger apparatus. The results showed that SEO yield in the optimal conditions of treatments was 119.7%, 206.6%, and 155.7% higher in UB, W/M‐UB, and CP‐UB pretreatments respectively, in comparison to control sample and optimized conditions were UB temperature: 37.3°C and UB time: 5.2 min at UB treatment, 33.9 of W/M ratio, 69.9°C of UB temperature and 6.9 min of UB time at W/M‐UB treatment and CP power: 22.176, UB temperature: 40.135 and UB time: 24.122 at CP‐UB treatment. Oxygenated monoterpenes were also higher in the essential oils (EOs) of all three treated plant materials. In conclusion, the SEO extraction yield improved by the application of the pretreatments in optimized conditions. The aim of this study was to increase the extraction efficiency of essential oil. Treatments were ultrasonic bath, water to material ratio, and cold plasma. Increasing the time of ultrasonic bath and cold plasma power led to a higher yield. Treatments with ultrasonic bath temperature and water/material ratio inversely affected the yield. The treatments raised the percentage of oxygenated monoterpenes slightly.

To investigate the effect of harvest height on the amassed elements and ash content of Hyssop (Hyssopus officinalis L.), an experiment was conducted in a randomized complete block design with three replications. Treatments included four harvest heights, i.e., 15, 25, 35, and 45 cm (from the tip of the plant) and the residual stalks. The dependent variables were the amassed content of elements N, K, P, Ca, Mg, Cu, Zn, and Pb in different heights of the plant and the associated ash content (total ash (TA), acid-insoluble ash (AA), and water-insoluble ash (WA)). The results showed that by moving from the upper shoots toward the ground, the amassed content of Mg, Ca, Cu, Zn, and Pb increased by 22.67%, 43.74%, 12.87%, 39.02%, and 85.04%, respectively. Further, a downward trend was observed for N (50.16%) and K (6.41%) content, while an upward trend reported for P (29.06%) content. As for the residual stalks, by moving from the upper shoots toward the ground, Mg, Ca, Cu, Zn, and Pb contents decreased by 1.01%, 21.03%, 9.11%, 17.02%, and 51.06%, respectively, while N and P contents increased by 60.59% and 3.15%, respectively, and a 34.74% increase was seen in P content. With increasing harvest height, TA, AA, and WA values increased by 33.48%, 27.03%, and 18.25%, respectively. As for the residues, these variables increased by 11.44%, 6.35%, and 5.22%, respectively. Our results showed that 15 cm harvest height had the highest quality with the lowest heavy metal content.