Exogenous putrescine treatment delays chilling injury in okra pod (Abelmoschus esculentus) stored at low storage temperature

Polyamine, particularly putrescine (Put) has been proposed to play important role in plant to cope with cold stress. Thus, the aim of this study was to determine the effect of polyamines treatment specifically Put on alleviating the CI in okra when exposed to low storage temperature. Okra pods were dipped into Put at 0, 0.5 mM, 1mM and 2mM and stored at 4 °C. The results showed that 2mM Put effectively reduced CI symptoms of okra. Interestingly, seed browning increased with severity of CI. Meanwhile, Put treatment significantly reduced seed browning by retarding the activity polyphenol oxidase (PPO) and peroxidase (POD) enzymes. Additionally, Put treatment elevated total phenolics, total antioxidant activity (DPPH radical scavenging activity and FRAP), antioxidant enzymes (CAT and SOD) activity and contributed to low hydrogen peroxide and malondialdehyde content

Physio-biochemical Responses of Okra (<i>Abelmoschus esculentus</i>) to Oxidative Stress Under Low Temperature Storage

Okra pods, commonly eaten at an immature stage, undergo quick postharvest deterioration due to high respiration, water loss, wilting, toughening and decay. As okra is a tropical crop, its pods are susceptible to chilling injury (CI) at low storage temperatures. The effects of low temperature storage on the physiobiochemical properties of okra pods were determined. Chilling injury symptoms were found only in pods stored at 4°C and were more apparent after transfer to 25°C. In seeds, the CI index was positively correlated with seed browning, H2O2 , malondialdehyde (MDA) content, and catalase (CAT) activity. Chilling-injured seeds had lower total phenolic content (TPC), antioxidant activity (DPPH scavenging activity and FRAP assay), peroxidase (POD), and superoxide dismutase (SOD) activities than non-injured seeds. Additionally, the seed browning index was related to high polyphenol oxidase (PPO) activity. In the pericarp, the CI index was also positively correlated with the H2O2 and MDA contents. The POD and SOD activities in chilling-injured pericarp were significantly lower than in non-injured pericarp. Chilling injury resulted in an initial increase in DPPH scavenging and CAT activities which later decreased as CI became severe. These results indicate that CI in okra is due to accumulation of H2O2 , and MDA, as well as its weak antioxidant defense mechanism. This resulted in development of CI symptoms, including seed browning

A Novel Technique Using Advanced Oxidation Process (UV-C/H2O2) Combined with Micro-Nano Bubbles on Decontamination, Seed Viability, and Enhancing Phytonutrients of Roselle Microgreens

Microbial contamination commonly occurs in microgreens due to contaminated seeds. This study investigated the decontamination effects of water wash (control), 5% hydrogen peroxide (H2O2 ), UV-C (36 watts), advanced oxidation process (AOP; H2O2 + UV-C), and improved AOP by combination with microbubbles (MBs; H2O2 + MBs and H2O2 + UV-C + MBs) on microbial loads, seeds’ viability, and physio-biochemical properties of microgreens from corresponding roselle seeds. Results showed that H2O2 and AOP, with and without MBs, significantly reduced total aerobic bacteria, coliforms, Escherichia coli (E. coli), and molds and yeast log count in seeds as compared to the control. Improved AOP treatment of H2O2 + UV-C + MBs significantly augmented antimicrobial activity against total bacteria and E. coli (not detected,) as compared to control and other treatments due to the formation of the highest hydroxy radicals (5.25 × 10−13 M). Additionally, H2O2 and combined treatments promoted seed germination, improved microbiological quality, total phenolic, flavonoids, and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH• ) activity of the grown microgreens. Ascorbic acid content was induced only in microgreens developed from H2O2 -treated seeds. Single UV-C treatment was ineffective to inactivate the detected microorganism population in seeds. These findings demonstrated that improved AOP treatment (H2O2 + UV-C + MBs) could potentially be used as a new disinfection technology for seed treatment in microgreens production

Effect of polyamines application on reducing chilling injury incidence in okra pod (Abelmoschus esculentus) stored at low storage temperature

Generally, immature okra pod is perishable and sensitive to chilling when exposed to temperature below 10 °C. Polyamines application has been claimed to be able to cope with low temperature stress due to their polycationic and antioxidant properties. In the present study, the effects of putrescine, spermidine and spermine on maintaining quality of stored okra pod were investigated. Immature okra pods were treated with putrescine, spermidine and spermine at two different concentrations (0.5 and 1.0 mM) with four replications per treatment. On the other hand, the control okra pods were only dipped in distilled water.All the pods were stored at 4 °C with 85 ± 5% relative humidityfor 12 days. Results showed that the okra pods treated with putrescine at both concentrations were significantly lower in chilling injury (CI) incidence (46 to 56% ) and weight loss (51 to 68% ) than the control. While spermidine and spermine showed no differences with control after 8storage days. Exogenous putrescine application resulted ina higher DPPH scavenging activity as well as antioxidant enzymes activity of catalase and peroxidase with respect to control after 12 days of storage. These responses could possibly be involved in chilling tolerance in okra pod during cold storag

Impact of electrostatic atomized water particles (EAWPs) treatment on chlorophyll degradation and delay ripening in Thai banana (Musa paradisiaca, cv. ‘Namwa’ banana) during storage

Electrostatic atomized water particles (EAWPs) treatment was applied to investigate its effect on chlorophyll (Chl) degradation and delaying of ripening in ‘Namwa’ banana. Banana fruits were pretreated with EAWPs generated from a device (Panasonic F-GMK01) for 0 (control), 0.5, 1.0, 1.5, and 3.0 h in a closed 50 L container, and then kept in perfolated polypropylene plastic bags and stored at ambient temperature (25±2 °C) under dark condition. The results showed that 1.0 h-EAWPs treatment best retained peel greenness with a significantly higher hue angle and lower L* value than other treatments on day 6. Also, the 1.0 h-EAWPs treatment maintained the total Chl content, firmness, total soluble solids (TSS) and delayed the ripening index (RI) of fruit accompanied with a delayed climacteric rise of ethylene and respiration rate compared to control. It was found that the 1.0 h-EAWP treatment induced accumulations of nitric oxide (NO) in peel tissues and suppressed the activities of Chl degrading enzymes (chlorophyllase, Mg-dechelatase, Chl-degrading peroxidase, and pheophytinase) in the peel. Furthermore, Chl derivatives levels (chlorophyllide a, pheophobide a, 132-hydroxychlorophyll a, and pheophytin a) were higher in fruits treated with EAWPs than the control fruits. The results suggest that EAWPs technology could be an alternative approach to delay the Chl degradation and ripening in ‘Namwa’ banana

Anthocyanin concentration and antioxidant activity in light-emitting diode (LED)-treated apples in a greenhouse environmental control system

Introduction. Anthocyanins are a group of flavonoids, and their synthesis is influenced by external and internal factors such as light, temperature, phytohormones and sugar concentration. A high anthocyanin concentration, which is related to redder coloration, is one of the factors of high-quality fruit. The effects of LED irradiation on the anthocyanin concentration and enzymatic and antioxidant activities in apple skin were studied. Materials and methods. Nine 8-year-old ‘Tsugaru’ apple trees (Malus domestica Borkh.) grafted onto Malling26 (M.26 EMLA) rootstocks planted in 45-L plastic pots covered with polyvinyl film (90% transmittance) and grown in a greenhouse were used. The effects of red or blue light-emitting diode (LED) irradiation on anthocyanin accumulation, the expression of MdMYB10 and UDP-glucose-flavonoid 3-O-glucosyltransferase (MdUFGT) and superoxide anion radical (O\hbox{$_{\mathrm{2}}^{\mathrm{-}})$} scavenging activity in the skin of ‘Tsugaru’ apples were investigated under early heating cultivation in a greenhouse. Results and discussion. The anthocyanin concentrations in red LEDtreated apples were increased compared with those of the blue LEDtreated apples and the untreated control at 130 days after full bloom (DAFB). The relative expression of MdMYB10 and MdUFGT genes at 130 DAFB was also highest in the skin of apples treated with red LED light. The skin of apple fruits treated with red or blue LED light showed significantly low EC50values. Conclusion. These results suggest that red LED irradiation may be used in a controlled environment such as a greenhouse to increase the anthocyanin synthesis and antioxidant activity in apple skin

Comparison of some physico-chemical parameters of kiwiberry (Actinidia arguta) cultivars from a cold climate

The Actinidia genus includes a number of commercial fruit species with a wide range of countries of origin. Some species such as A. arguta or A. kolomikta are characterized by a high level of resistance to frost. The aim of this study was to compare the fruit of selected cultivars of kiwiberry. In the kiwiberry fruit, sucrose was the predominant type of sugar. Citric acid was dominant in all samples; it was most represented in the pulp of kiwiberry seedlings and in the skin of kiwiberry ‘Issai’. Kiwiberry fruits feature a higher ascorbic acid content in the skin in comparison with the commercial A. chinensis cultivars. Antioxidant activity of kiwiberry fruit skin was up to 18 times higher than that of the pulp. In view of the kiwiberry fruit having no hair, it is possible to eat the whole fruit, including the skin containing substances beneficial to health

Application of Cytokinin under Modified Atmosphere (MA) Delays Yellowing and Prolongs the Vase Life of <i>Davallia solida</i> (G. Forst.) Sw. Leaves

Cut leaves of Davallia solida are widely used in bouquet greenery. However, the leaves wilt and yellow after seven days. Postharvest applications of exogenous cytokinins (CKs), a plant growth regulator (PGR), preventing senescence in many green leafy plants, were studied by pulsing cut D. solida leaves with 6-benzylamiopurine (BA) at a concentration of 100 ppm, or thidiazuron (TDZ) at a concentration of 10 μM for 24 h, compared with distilled water as a control, and then placing the ferns in a controlled room (21 + 2 °C, 70–80% relative humidity (RH), under cool-white fluorescent lights for 12 h/d). Pulsing with BA and TDZ delayed leaf yellowing while preserving chlorophyll (Chl) content. This was due to reduced Chl-degrading enzyme activities on day 8 of the vase life of the leaves, resulting in longer display life of 11.1 and 11.5 days, respectively. TDZ delayed Chl breakdown on day 8 of the vase life of leaves more than was the case for BA. Subsequently, leaves were pulsed in 10 μM TDZ, or distilled water for 24 h, and then 10 leaves from each treatment were packaged in a 25 × 30 cm, 25-μm thickness BOPP bag. All the packages were stored at 10 °C in 10 h/d light for one, two and three weeks, then unpacked and placed in distilled water. Pulsing with TDZ before one-week storage delayed leaf yellowing, maintained Chl content and extended their vase life to 9.6 days compared with one-, two-, and three-week control leaves, which had a vase life of 6.2, 5.8, and 3.6 days, respectively. After one week, the relative fresh weight of the leaves and water uptake did not alter between the control and TDZ groups. The activities of Chl degradation enzymes in the leaves of D. solida pulsed with TDZ prior to storage were significantly suppressed, related to higher Chl content and a lower percentage of leaf yellowing than the control, resulting in a longer vase life of 9.0 days, while the control lasted 7.0 days. A 10 µM TDZ pulsing treatment significantly prevented the yellowing of D. solida fronds during the vase period or storage period, and one-week storage under MA with light conditions is recommended for retaining postharvest quality after storage

Bioactive Composition and Nutritional Profile of Microgreens Cultivated in Thailand

Microgreens are young and tender leafy vegetables that have gained wider consumer ac‐ceptance. This is attributed to their low caloric composition and rich micronutrient and antioxidant composition. The present study investigated the bioactive composition and proximate analysis of fourteen microgreens belonging to Brassicaceae, Fabaceae, Pedaliaceae, Polygonaceae, Convolvu‐laceae, and Malvaceae. All the microgreens showed low calories (20.22 to 53.43 kcal 100 g−1) and fat (0.15 to 0.66 g 100 g−1), whilst mung bean and lentil microgreens showed considerable amounts of carbohydrate (7.16 g 100 g−1) and protein (6.47 g 100 g−1), respectively. Lentil microgreens had the highest total chlorophyll (112.62 mg 100 g−1) and carotenoid (28.37 mg 100 g−1) contents, whilst buck‐wheat microgreens showed the highest total phenolic content (268.99 mg GAE 100 g−1) and DPPH• scavenging activity (90.83 mM TEAC g−1). The lentil microgreens also presented high ascorbic acid content (128.70 mg 100 g−1) along with broccoli, Chinese kale, purple radish, and red cabbage mi‐crogreens (79.11, 81.33, 82.58, and 89.49 mg 100 g−1, respectively). Anthocyanin content was only detected in purple radish (0.148 mg CGE 100 g−1) and red cabbage (0.246 mg CGE 100 g−1). The results provide basic information and highlight the benefits of utilizing genetic biodiversity to ob‐tain microgreens with the desired nutrients and antioxidants