scholarly journals Chlorophyll Fluorescence as a Nondestructive Indicator of Broccoli Quality during Storage in Modified-atmosphere Packaging

HortScience ◽  
2000 ◽  
Vol 35 (2) ◽  
pp. 256-259 ◽  
Author(s):  
Jennifer R. DeEll ◽  
Peter M.A. Toivonen

The objective of this study was to determine if chlorophyll fluorescence could be used as an indicator of anaerobic respiration in broccoli (Brassica oleracea L., Italica group) during modified-atmosphere packaging (MAP). Two types of packages were used, PD-941 bags, which provided optimum MAP conditions for broccoli (≈3 kPa O2 plus 5 kPa CO2), and PD-961EZ bags, which allowed the CO2 to accumulate (≈11 kPa CO2). After 28 days in MAP at 1 °C, the broccoli from both types of bag had similar appearances and weight losses. However, broccoli held in the PD-961EZ bags had developed slight to moderate alcoholic off-odors and had higher ethanol, acetaldehyde, and ethyl acetate content, as compared with broccoli in PD-941 bags. Chlorophyll fluorescence parameters (Fv/Fm, T1/2, Fmd, and ΦPSII) were lower for broccoli held in the PD-961EZ bags than in PD-941 bags, and these differences increased with storage duration. These results indicate that chlorophyll fluorescence is a reliable, rapid, nondestructive indicator of broccoli quality during MAP, and that it could be used to determine if broccoli has developed off-odors without opening the bag and disrupting the package atmosphere.

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 483E-484
Author(s):  
J.R. DeEll ◽  
P.M.A. Toivonen

When the gas concentrations of modified atmosphere packaging (MAP) become extreme for broccoli (<2 kPa O2 and >10 kPa CO2), off-odors and off-flavors may develop via anaerobic respiration, rendering it unmarketable. We recently showed that chlorophyll fluorescence decreases when broccoli switches to anaerobic behavior in MAP. The objectives of this study were to determine: 1) if chlorophyll fluorescence returns to normal levels after the package is opened and hence the broccoli is exposed to ambient air, and 2) if chlorophyll fluorescence is related to off-odors that develop. Broccoli heads were held in MAP (2 to 3 kPa O2 and >10 kPa CO2) at 0 to 1 °C for 4, 7, 14, 21, or 28 days, and then 5 days in ambient air at 0 to 1 °C. Chlorophyll fluorescence of the broccoli decreased dramatically in MAP, and remained low during the subsequent 5 days in ambient air. Similarly, off-odors became worse and acetaldehyde, ethanol, and ethyl acetate increased in the broccoli with time in MAP. However, these compounds slightly decreased during the subsequent 5 days of storage in ambient air. Chlorophyll fluorescence parameters correlated negatively with off-odor development and acetaldehyde, ethanol, and ethyl acetate levels in the tissue.


2006 ◽  
Vol 39 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Marie KUMMEROVÁ ◽  
štěpán ZEZULKA ◽  
Jana KRULOVÁ ◽  
Jan TŘÍSKA

The effect of increasing concentrations (0·01, 0·1, 1 and 5 mg l−1) of intact (FLT) and photo-modified (phFLT) fluoranthene and the duration of exposure (1, 2, 3, 5 and 7 days) on the chlorophyll fluorescence parameters (F0, FV/FM, and ΦII) of symbiotic algae in the thalli of two foliose lichens Lasallia pustulata and Umbilicaria hirsuta was investigated. In addition the FLT concentration in thalli of both lichen species was determined and a bioconcentration factor (BCF) was calculated. The results obtained demonstrated that the concentrations of FLT and especially phFLT (1 and 5 mg l−1) applied affected primary photochemical processes of photosynthesis in the algae of both lichen species. The F0 value increased and the FV/FM and ΦII values decreased. The fluoranthene content in the thallus of both lichen species increased with increasing FLT concentration in the environment.


Author(s):  
Guotao Peng ◽  
Zhengqiu Fan ◽  
Xiangrong Wang ◽  
Chen Chen

<p>The frequent outbreak of cyanobacterial blooms has become a worldwide phenomenon in freshwater ecosystems. Studies have elucidated the close relationship between harmful algal blooms and nutrient contents, including the loading of nitrogen and the ratios of nitrogen (N) and phosphorus (P). In this study, the effect of inorganic (nitrate and ammonium) and organic (urea) nitrogen at varied N/P ratios on the <em>Microcystis</em> <em>aeruginosa</em> FACHB-905 accumulation and photosynthesis was investigated.  The optimal NO<sub>3</sub>/P in this study were 30~50 indicated by the cell abundance (4.1×10<sup>6</sup>/mL), pigment concentration (chlorophyll a 3.1 mg/L,  phycocyanin 8.3mg/L), and chlorophyll fluorescence parameters (<em>rETR</em>, <em>E<sub>k</sub>, α, φPSII</em> and <em>F<sub>v</sub>/F<sub>m</sub> </em>values), while too high NO<sub>3</sub>-N (N/P=100:1) would cause an intracellular nitrate inhibition, leading to a decrease of photosynthetic activity. In addition, low concentration of NH<sub>4</sub>-N (N/P=4:1) would favor the <em>M. aeruginosa </em>growth and photosynthesis, and high NH<sub>4</sub>/P ratio (&gt;16) would rise the ammonium toxicity of algal cells and affect the N assimilation. In urea treatments, <em>M. aeruginosa </em>responded similarly to the NH<sub>4</sub>-N treatments both in growth curves and pigment contents, and the favorable N/P ratio was between 16~30, suggested by the chlorophyll fluorescence parameters. The results demonstrated that the various chemical forms of N and N/P ratios have a significant impact on <em>Microcystis</em> abundance and photosynthesis. More work is needed to figure out the mechanism of nitrogen utilization by <em>Microcystis</em> and  the photosynthetic response to nutrient stress at the molecular level.</p>


Agronomy ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 213 ◽  
Author(s):  
Cristhian C. Chávez-Arias ◽  
Sandra Gómez-Caro ◽  
Hermann Restrepo-Díaz

Cape gooseberry has coped with abiotic and biotic stresses such as prolonged waterlogging periods and vascular wilt in recent years. The aim of this study was to evaluate the influence of four waterlogging periods on stomatal conductance (gs), leaf water potential (Ψwf), plant growth, leaf photosynthetic pigments, malondialdehyde (MDA) production, proline content and chlorophyll fluorescence parameters in cape gooseberry plants infected with Fusarium oxysporum f. sp. physali (Foph). Two-month-old ecotype “Colombia” plants were arranged in a completely randomized factorial design in eight treatments: plants without waterlogging (control), plants with waterlogging for 4, 6 and 8 d with and without Foph, respectively. The area under the disease progress curve was higher in inoculated plants subjected to 6 and 8 d of waterlogging (55.25 and 64.25) compared to inoculated plants but without waterlogging (45.25). The results also showed a lower plant growth, gs, Ψwf, leaf photosynthetic pigments and chlorophyll fluorescence parameters (Fv/Fm, electron transport rate (ETR), Y (II) and qP) as waterlogging periods in plants with Foph increased. However, this group of plants showed a greater proline and malondialdehyde (MDA) accumulation and a higher NPQ. In conclusion, cape gooseberry shows a low acclimation to waterlogging conditions of more than 6 d in soils with Foph.


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