Effect of Oxidase Stresses on Glucosinolates Profile in Broccoli Florets During Postharvest Storage (original) (raw)
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Postharvest Biology and Technology, 2020
Abiotic stresses are oxidative in nature and cause generation of reactive oxygen species (ROS) in plant bodies. Severe stresses can be harmful to the plant tissue, whereas sub-acute or lower doses of stresses could enhance or induce protective mechanisms, a biological phenomenon known as hormesis. The objective of this work was to examine the effect of hormetic as well as high doses of UV-B on the quality along with glucosinolate and hydroxy-cinnamate contents in broccoli florets during storage. An UV-B dose of 1.5 kJ m −2 was found to be hormetic from the color retention response. Color development, weight loss and respiration rate were monitored during 21 d of storage at 4°C. The gene expression of dihomomethionine N-hydroxylase (CYP79F1), tryptophan N-hydroxylase 2 (CYP79B3), phenylalanine N-hydroxylase (CYP79A2), phenylalanine ammonia-lyase (PAL), chalcone synthase (CH) and flavanone 3-hydroxylase (F3H1) in the treated broccoli was also evaluated. The antioxidant capacity and the profiles of glucosinolates and hydroxy-cinnamates were determined for up to 14 d in broccoli florets stored at 4°C by LC-MS. The hormetic dose of UV-B was effective in delaying the yellowing of broccoli florets. The initial respiration rate of the florets treated with the hormetic and a high dose (7.2 kJ m −2) was significantly high. The antioxidant capacity of florets was higher in UV-B treated florets relative to the control. The titers of indole-type glucosinolates and hydroxycinnamates in broccoli were significantly (p < 0.05) higher with both doses of UV-B compared to the non-exposed florets. UV-B appears to exhibit balanced effects with respect to quality preservation and enhancement of phyto-compounds in broccoli florets. Results showed a good correlation between gene expression of CYP79B3, and the titers of indole glucosinolates in the treated broccoli florets, suggesting that the target of UV-B is likely to be the branch pathway of indole glucosinolates.
Phytochemical Enhancement in Broccoli Florets after Harvest by Controlled Doses of Ozone
Foods
The objective of this work was to examine the effect of controlled doses of O3 (0, 5 µL L−1 of O3 for 60 min, and 5 µL L−1 of O3 for 720 min) on the quality and phytochemical content of broccoli florets during postharvest storage. The optimal dose was found at 5 µL L−1 of O3 for 60 min, from the color retention of broccoli florets exposed to the gas treatment. Overall, the antioxidant capacity of the florets was significantly affected by both doses of O3 compared to the non-exposed florets. The profile of glucosinolates was determined for up to 14 days in broccoli florets stored at 4 °C by LC-MS. The amount of total glucobrassicins and total hydroxy-cinnamates in florets significantly (p ≤ 0.05) improved by the application of 5 µL L−1 of O3 for 60 min compared to non-treated florets. The up-regulation of genes of the tryptophan-derived glucosinolate pathway was observed immediately after both treatments. The gene expression of CYP79A2 and CYP79B3 in broccoli was significantly higher...
Postharvest Biology and Technology, 2007
Broccoli (Brassica oleracea L.) tissue held in a controlled atmosphere (CA; 10% carbon dioxide and 5% oxygen) senesces more slowly than tissue held in air. CA-treated broccoli tissues lose less water and soluble sugars, have lower protease activity, and have no significant loss of color (hue angle, chlorophyll content) for 96 h after harvest (20 • C, dark) compared to tissue held in air that starts to senesce and yellow after 48 h. The current study examined differential gene expression in broccoli tissues in response to postharvest CA treatment. This genetic analysis was undertaken to identify CA-responsive genes that may act as signaling elements and repress postharvest senescence processes. CA-responsive genes with up-and down-regulated expression (compared to air controls) were isolated after a 6 h CA treatment by differential display-polymerase chain reaction. The candidate CA-responsive genes included a number of novel genes without previously assigned functions, and genes of known function previously found to be regulated by stress (e.g. dehydration, salt stress, low temperature, and sugar starvation).
Plant & cell physiology, 2012
Only a few environmental factors have such a pronounced effect on plant growth and development as ultraviolet light (UV). Concerns have arisen due to increased UV-B radiation reaching the Earth's surface as a result of stratospheric ozone depletion. Ecologically relevant low to moderate UV-B doses (0.3-1 kJ m -2 d -1 ) were applied to sprouts of the important vegetable crop Brassica oleracea var. italica (broccoli), and eco-physiological responses such as accumulation of nonvolatile secondary metabolites were related to transcriptional responses with Agilent One-Color Gene Expression Microarray analysis using the 2Â204 k format Brassica microarray. UV-B radiation effects have usually been linked to increases in phenolic compounds. As expected, the flavonoids kaempferol and quercetin accumulated in broccoli sprouts (the aerial part of the seedlings) 24 h after UV-B treatment. A new finding is the specific UV-Bmediated induction of glucosinolates (GS), especially of 4-methylsulfinylbutyl GS and 4-methoxy-indol-3-ylmethyl GS, while carotenoids and Chl levels remained unaffected. Accumulation of defensive GS metabolites was accompanied by increased expression of genes associated with salicylate and jasmonic acid signaling defense pathways and upregulation of genes responsive to fungal and bacterial pathogens. Concomitantly, plant pre-exposure to moderate UV-B doses had negative effects on the performance of the caterpillar Pieris brassicae (L.) and on the population growth of the aphid Myzus persicae (Sulzer). Moreover, insect-specific induction of GS in broccoli sprouts was affected by UV-B pre-treatment.
Frontiers in Plant Science, 2016
Broccoli contains high levels of bioactive molecules and is considered a functional food. In this study, postharvest treatments to enhance the concentration of glucosinolates and phenolic compounds were evaluated. Broccoli whole heads were wounded to obtain florets and wounded florets (florets cut into four even pieces) and stored for 24 h at 20 • C with or without exogenous ethylene (ET, 1000 ppm) or methyl jasmonate (MeJA, 250 ppm). Whole heads were used as a control for wounding treatments. Regarding glucosinolate accumulation, ET selectively induced the 4-hydroxylation of glucobrassicin in whole heads, resulting in ∼223% higher 4-hydroxyglucobrassicin than time 0 h samples. Additionally, glucoraphanin was increased by ∼53% in whole heads treated with ET, while neoglucobrassicin was greatly accumulated in wounded florets treated with ET or MeJA, showing increases of ∼193 and ∼286%, respectively. On the other hand, although only whole heads stored without phytohormones showed higher concentrations of phenolic compounds, which was reflected in ∼33, ∼30, and ∼46% higher levels of 1,2,2-trisinapoylgentiobose, 1,2-diferulolylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose, respectively; broccoli florets stored under air control conditions showed enhanced concentrations of 3-O-caffeoylquinic acid, 1,2-disinapoylgentiobiose, and 1,2-disinapoyl-2-ferulolylgentiobiose (∼22, ∼185, and ∼65% more, respectively). Furthermore, exogenous ET and MeJA impeded individual phenolics accumulation. Results allowed the elucidation of simple and effective postharvest treatment to enhance the content of individual glucosinolates and phenolic compounds in broccoli. The stressed-broccoli tissue could be subjected to downstream processing in order to extract and purify bioactive molecules with applications in the dietary supplements, agrochemical and cosmetics markets.
Ozone and 1-Methylcyclopropene alter the postharvest quality of broccoli
Fresh broccoli (Brassica oleracea L. Italica group) fl orets untreated or treated with 1 µL·L -1 1-methylcyclopropene (1-MCP) for 14 h, were stored at 12 °C with 0, 200, or 700 nL·L -1 ozone. Senescence parameters were evaluated after 0, 1, 2, 5, 8, or 12 days of storage. Treatment with 1-MCP delayed the yellowing of fl orets, and at day 5 the hue angle of 1-MCP treated fl orets was 116° (green) compared to 102° (yellow) for the control. Respiration rates of fl orets were reduced by 1-MCP for the fi rst 5 days. The 1-MCP treatment maintained higher chlorophyll fl uorescence expressed as F v /F m during 12 days of storage. Also, 1-MCP reduced dimethyl trisulfi de production, which contributes to off-odor development in broccoli fl orets. Compared with the controls, fl orets stored in 200 nL·L -1 ozone had less mold growth and yellowed more slowly, but no differences were observed in respiration, ethylene production, or F v /F m . Florets stored in 700 nL·L -1 ozone were greener than fl orets held in air or 200 nL·L -1 ozone. Interestingly, chlorophyll fl uorescence of the fl orets stored in 700 nL·L -1 ozone decreased signifi cantly and at day 12, F v /F m was only 30% of its initial value. Ozone at 700 nL·L -1 stimulated respiration and ethylene production of fl orets after 1 day of storage, and caused visible damage in the form of increased weight loss and browning of the fl oret stem ends. Treatment of broccoli with 1-MCP alone or in combination with 200 nL·L -1 ozone maintained the quality and extended the shelf life of broccoli fl orets.
International Journal of Vegetable Science, 2016
Health promoting bioactive compounds in broccoli (Brassica oleracea L. var. italica) florets decrease in nutritional value after harvest. Ultraviolet (UV)-C radiation (254 nm) is a physical technology to extend postharvest life of vegetables. Broccoli florets from cv. Premium Crop, were treated with 0 m −2 •s −1 (control), 1.5, 4.5, or 10 kJ•m −2 •s −1 of UV-C and subsequently stored at 4°C for 12 days. All treatments increased total polyphenols content and increased up to 21% above the initial value during storage. The higher the UV-C dose, the higher the total antioxidant capacity values that were reached. Generally total chlorophyll content decreased, but higher chlorophyll retention was when broccoli florets were radiated with 4.5 and 10 kJ•m −2 •s −1 of UV-C. Treatment with UV-C of 10 kJ•m −2 •s −1 caused the highest retention of sugar. Decreasing protein content in broccoli florets during storage occurred but samples treated with 4.5 and 10 kJ•m −2 •s −1 had higher protein contents. UV-C treatment is a nonchemical technique to delay senescence and preserve quality and nutritional value of broccoli up to 12 days at 4°C.
Journal of the Science of Food and Agriculture, 2012
BACKGROUND: Broccoli is a highly perishable vegetable that shows enhanced postharvest senescence and intense de-greening caused by chlorophyll degradation. One of the key steps of chlorophyll catabolism is the opening of chlorophyll tretrapyrrole catalysed by pheophorbide a oxygenase (PaO). In this study the expression of a gene encoding a putative PaO was characterised under several chemical and physical treatments. RESULTS: A fragment of a gene encoding a PaO from broccoli (BoPaO) was cloned. The expression of BoPaO showed an important increment during postharvest senescence, in correlation with chlorophyll degradation. Furthermore, broccoli heads were treated with the hormones cytokinin and ethylene. Cytokinin delayed the increment in BoPaO expression, while ethylene accelerated the process. Also, several postharvest treatments were applied in order to evaluate their effect on BoPaO expression. Samples treated with modified atmosphere, hot air, UV-C or white light showed a delay in chlorophyll degradation and de-greening. In most cases the treatments also delayed the increment in BoPaO expression during senescence. CONCLUSION: A close correlation between chlorophyll degradation and BoPaO expression was found during broccoli senescence. This relationship was corroborated in samples treated with different hormonal and physical applications.
Postharvest Biology and Technology, 2017
Postharvest UV exposure has been useful to i) delay senescence and ii) induce the accumulation of bioactive compounds in some vegetable species. However, no studies have been conducted to determine the treatment conditions (radiation dose and intensity) required to maximize these two diverse responses. In this work, we evaluated the effect of UV-B irradiation intensity (Control: 0, Low: 3.2, Medium: 4.0 and High: 5.0 W/m 2) and dose (0, 2, 4, 8, 12 kJ/m 2) on quality retention and antioxidant capacity of fresh broccoli florets during storage (4 C for 17 days). Exposure to Low UV-B radiation and dose (2, 4 kJ/m 2) reduced broccoli weight loss, delayed yellowing and improved chlorophyll and chlorophyllide retention. After long term storage, no marked improvement on the antioxidant capacity was found regardless of the irradiation condition. Evaluations at short time after UV-B exposure (0, 2, 6, 18 h) indicated that the treatments elicited antioxidant accumulation. Greatest antioxidant capacity was found in broccoli subjected to High intensity UV-B. Increased levels of aliphatic glucosinolates were found 18 h after the UV-B irradiation, whereas phenolic antioxidants peaked 6 h after the treatment. Results showed that Low UV-B doses and intensities delayed chlorophyll degradation and may be useful to complement refrigeration in fresh broccoli. Instead, High intensity UV-B exposure may be better suited as a pre-treatment to increase the antioxidant capacity prior to further processing such us freezing.
Food Chemistry, 2010
UV-B irradiation was applied to broccoli florets to investigate its effect on chlorophyll degradation and chlorophyll-degrading enzyme activities in stored broccoli. Broccoli florets were irradiated with UV-B doses at 4.4, 8.8 and 13.1 kJ m-2 and then kept at 15 ºC in darkness. We found that a UV-B dose of at least 8.8 kJ m-2 efficiently delayed the decrease of the hue angle value and the contents of chlorophylls a and b. Chlorophyllide a and 13 2-hydroxychlorohyll a gradually decreased with senescence. Pheophorbide a and pyropheophorbide a levels were significantly higher in broccoli without UV-B treatment. Chlorophyllase and chlorophyll-degrading peroxidase activities with UV-B treatment were suppressed, as well as the activity of Mg-dechelatase. Mgdechelating substance activity was also suppressed with this treatment. We concluded that UV-B treatment effectively suppressed chlorophyll degradation in broccoli florets during storage, suggesting that the effect could be due to the suppression of chlorophylldegrading enzyme activities.