Chitosan nano-biopolymer/Citrus paradisi peel oil delivery system enhanced shelf-life and postharvest quality of cherry tomato.

Grapefruit peel essential oil (CpEO) was loaded on chitosan (Cs) nano-biopolymer by ionic gelation method and its effect on physicochemical properties of cherry tomatoes was evaluated during 18 days of storage at 10 °C. The highest loading capacity and encapsulation efficiency were obtained from the weight ratio of 1:0.25 Cs to oil. TEM, DLS and FTIR were used to characterize the nanoparticles. The release of the oil from the nanoparticles followed the Fickian diffusion model. CpEO-CsNPs-CO and CpEO-CsNPs-RE treatments reduced ethylene production and respiration rate and indicated a significant and promising effect on increasing the level of antioxidant enzymes (CAT and POD), slowing down the loss of ascorbic acid and total phenolic content and consequently, maintaining antioxidant capacity. These treatments prevented a rapid decline in TSS and TA and an increase in lycopene and MDA level, and maintained the firmness, weight, and color of the fruits throughout storage period.

Metabolomics analysis of milk thistle lipids to identify drought-tolerant genes.

Milk thistle is an oil and medicinal crop known as an alternative oil crop with a high level of unsaturated fatty acids, which makes it a favorable edible oil for use in food production. To evaluate the importance of Milk thistle lipids in drought tolerance, an experiment was performed in field conditions under three different water deficit levels (Field capacity (FC), 70% FC and 40% FC). After harvesting seeds of the plant, their oily and methanolic extracts were isolated, and subsequently, types and amounts of lipids were measured using GC-MS. Genes and enzymes engaged in biosynthesizing of these lipids were identified and their expression in Arabidopsis was investigated under similar conditions. The results showed that content of almost all measured lipids of milk thistle decreased under severe drought stress, but genes (belonged to Arabidopsis), which were involved in their biosynthetic pathway showed different expression patterns. Genes biosynthesizing lipids, which had significant amounts were selected and their gene and metabolic network were established. Two networks were correlated, and for each pathway, their lipids and respective biosynthesizing genes were grouped together. Four up-regulated genes including PXG3, LOX2, CYP710A1, PAL and 4 down-regulated genes including FATA2, CYP86A1, LACS3, PLA2-ALPHA were selected. The expression of these eight genes in milk thistle was similar to Arabidopsis under drought stress. Thus, PXG3, PAL, LOX2 and CYP86A1 genes that increased expression were selected for protein analysis. Due to the lack of protein structure of these genes in the milk thistle, modeling homology was performed for them. The results of molecular docking showed that the four proteins CYP86A1, LOX2, PAL and PXG3 bind to ligands HEM, 11O, ACT and LIG, respectively. HEM ligand was involved in production of secondary metabolites and dehydration tolerance, and HEM binding site remained conserved in various plants. CA ligands were involved in synthesis of cuticles and waxes. Overall, this study confirmed the importance of lipids in drought stress tolerance in milk thistle.

Chitosan-Selenium Nanoparticle (Cs-Se NP) Foliar Spray Alleviates Salt Stress in Bitter Melon.

Salt stress severely reduces growth and yield of plants. Considering the positive effects of selenium (Se) and chitosan (Cs) separately against abiotic stress, in these experiments, we synthesized chitosan-selenium nanoparticles (Cs-Se NPs) and investigated their ability to reduce the negative effects of salt stress on growth and some biochemical parameters of bitter melon (Momordica charantia). Bitter melon plants were grown at three NaCl salinity levels (0, 50, and 100 mM) and a foliar spray of Cs-Se NPs (0, 10, and 20 mg L-1) was applied. Some key morphological, biochemical, and physiological parameters in leaf samples and essential oil from fruit were measured at harvest. Salinity decreased growth and yield while foliar application of Cs-Se NPs increased these critical parameters. Furthermore, Cs-Se NPs enhanced bitter melon tolerance to salinity by increasing antioxidant enzyme activity, proline concentration, relative water content, and K+, and decreasing MDA and H2O2 oxidants and Na aggregation in plant tissues. Yield was also improved, as the highest amount of essential oils was produced by plants treated with Cs-Se NPs. Generally, the greatest improvement in measured parameters under saline conditions was obtained by treating plants with 20 mg L-1 Cs-Se NPs, which significantly increased salinity tolerance in bitter melon plants.

Chitosan nanoparticles-loaded Citrus aurantium essential oil: a novel delivery system for preserving the postharvest quality of Agaricus bisporus.

BACKGROUND: One of the main problems in the button mushroom industry is the rapid deterioration of fruit bodies after harvest. Today, nanotechnology has become a more reliable technique to improve the quality of products in food packaging. In the present study, the effectiveness of chitosan nanoparticles containing Citrus aurantium essential oil on postharvest quality of white button mushroom was examined and compared to essential oil fumigation and control treatments. RESULTS: Based on high-resolution transmission electron microscopy and dynamic light scattering, nanoparticles exhibited a spherical shape of 20-60 nm diameter. The results revealed that the application of chitosan nanoparticles loaded with C. aurantium oil significantly decelerated the rate of color change, weight loss and firmness compared to fumigation with essential oil and control treatments. Treatment of fruit bodies with chitosan nanoparticles loaded with C. aurantium oil promoted the accumulation of phenolic compounds and ascorbic acid, and resulted in increases in catalase and superoxide dismutase and a decrease in polyphenol oxidase activities, as the highest antioxidant capacity was observed after 15 days of cold storage. CONCLUSION: This present research demonstrates that gradual release of C. aurantium essential oil from chitosan nanoparticles could be an effective and practical method for extending the shelf life of white button mushroom up to 15 days without significant decrease in antioxidant capacity. © 2018 Society of Chemical Industry.

Development and characterization of nano biopolymer containing cumin oil as a new approach to enhance antioxidant properties of button mushroom.

The aim of present study was to design a controlled release system using Cuminum cyminum essential oil loaded chitosan nanoparticles (CEO-CSNPs) and evaluate its effect on catalase (CAT), glutathione reductase (GR), peroxidase (POD) activity and ascorbic acid content of Agaricus bisporus fruit bodies during 20days of storage at 4°C. The success of encapsulation was evaluated through TEM, DLS, FT-IR and spectrophotometry and its release behavior was studied in buffer solutions with different pH. The CEO-CSNPs exhibited an average size of 30 to 80nm with a spherical shape. Encapsulation efficiency (EE) and loading capacity (LC) were 4.46 to 17.89% and 2.47 to 6.68%, respectively. The highest CAT and GR activity was observed in samples packed with CEO-CSNPs after 15days of storage. In contrast, POD activity reached a peak at the end of storage in control samples. Interestingly, after 20days the level of POD increased 17.13% in CEO-CSNPs treatment, as compared with the initial level of the mentioned enzyme. At the end of storage, ascorbic acid content in samples treated with CEO-CSNPs was significantly higher than that detected in the control samples. In brief, application of CEO loaded chitosan nanoparticles in packages effectively increased the antioxidant activity in white button mushroom and showed promising results for extending the shelf life of treated samples.

Metal oxides as a biostimulator for upregulation of genes involved in the biosynthesis of Rebaudioside- A.

Stevia rebaudiana Bertoni is a kind of perennial medicinal plant with sweetening properties which belongs to Asteraceae family. Its leaves with fundamental glycoside compounds consist of both a sugar part and a non-sugar sector. One of the glycoside compounds is Rebaudioside- A which has a greater importance in business. This experiment was conducted to evaluate the effects of Ag2O, CrO3, PbO, Fe2O3, BaO and TiO2 on the expression pattern of these genes in the Stevia rebaudiana. Rebaudioside- A biosynthesis was repeated 3 times with concentrations of 50, 100 and 200µM. Also, the results of the study pertaining to the expression pattern of these genes showed that metal oxides have led to an increase in the expression of the regulatory genes involved in biosynthesis of Rebaudioside- A. According to the expression profile, it was found that its effect on DXR, HDS, HDR, IDI and CPPS genes is more than other genes. The peak HPLC indicated for stevioside and Rebaudioside- A represents an increase in the production of this active ingredient under the influence of all treatments. In general, the expression profile of these genes and the results of HPLC show that whatever going to the end of the pathway of production of Rebaudioside- A, the activity of the enzymes increases under the influence of these treatments, and eventually a greater amount of Rebaudioside- A will be produced. This process shows that metal oxides will have a significant effect on the biosynthesis of Rebaudioside- A.