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Use of a Chlorophyll Fluorescence Detector to Monitor Grape Dehydration
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Agriculture and Agriculture et Agri-Food CanadaAgroalimentaireCanada Ali A Ramin, Robert K. Prange and John M. DeLong Atlantic Food and Horticulture Research Centre Kentville, Nova Scotia, Canada
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1.Introduction to chlorophyll fluorescence (CF) - CF curve – Fo, Fm, Fv = Fm-Fo - identification of Fo as most important 2. Design of the HarvestWatch system - produces F α as an estimate of Fo - important features of HarvestWatch system 3. Applications of HarvestWatch system - control O 2 in CA stores - monitor water loss in fruit, e.g. grapes 4. Concluding Remarks
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1. Introduction to chlorophyll fluorescence (CF) - CF curve – Fo, Fm, Fv = Fm-Fo - Identification of Fo as most important 2. Design of the HarvestWatch system - Produces Fα as an estimate of Fo - Important features of HarvestWatch system 3. Applications of HarvestWatch system - Control O 2 in CA stores - Monitor water loss in fruit, e.g. grapes 4. Concluding Remarks
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Fluorescence (red) is at ca. 740 nm (far-red) Known since the 1930’s
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Fo Typical Chlorophyll Fluorescence Curve Fo changes in response to stress 0.2 sec Add modulating light (LED) Add saturating light
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1. Introduction to chlorophyll fluorescence (CF) - CF curve – Fo, Fm, Fv = Fm-Fo - Identification of Fo as most important 2. Design of the HarvestWatch system - Produces Fα as an estimate of Fo - Important features of HarvestWatch system 3. Applications of HarvestWatch system - Control O 2 in CA stores - Monitor water loss in fruit, e.g. grapes 4. Concluding Remarks
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Output Scans Hub Sensors System PC with HarvestWatch Software HarvestWatch System components Sensor in Apple Storage
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Fluorescence vs. Photon flux
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Typical Fluorescence Scans (Healthy Product) F (Fo at zero irradiance) does not change F values
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Typical Fluorescence Scans (Stressed Product) F (Fo at zero irradiance) changes F values
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Features of HarvestWatch System Durable – no moving parts Single initial cost Easy to install Continuous measurement – 24 h/day Very sensitive to small changes in Fα Tech. Support - Isolcell Res. Support – Ag. & Agri-Food Canada Covers large surface area
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1. Introduction to chlorophyll fluorescence (CF) - CF curve – Fo, Fm, Fv = Fm-Fo - Identification of Fo as most important 2. Design of the HarvestWatch system - Produces Fα as an estimate of Fo - Important features of HarvestWatch system 3. Applications of HarvestWatch system - Control O 2 in CA stores - Monitor water loss in fruit, e.g. grapes 4. Concluding Remarks
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“specific O 2 concentrations at which Fo suddenly increases”
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Experimentation Chlorophyll-containing fruits and vegetables Fruit - apple, pear, banana, kiwifruit, mango, avocado Vegetables - cabbage, green pepper, iceberg lettuce, romaine lettuce Apple PearCabbage
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Treatments 1. ambient O 2 2. programmed rapid decrease in O 2 Responses simultaneous O 2 and F values Sample JarsCA Jar and Sensor unit
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Low Oxygen Stress (Apple)
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Low Oxygen Stress (Pear)
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Low Oxygen Stress (Cabbage)
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Other Stresses Detected by F High CO 2 e.g. Cabbage Monitoring water loss
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Monitoring Water Loss F declines, e.g. in grape berries Postharvest: Preharvest (field): New Fluorescence Induction and Relaxation (FIRe) system may be better choice than HarvestWatch (See following slides)
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Lid with HarvestWatch Sensor and 4 LED’s Sensor LED Base with grapes Postharvest Water Loss in Grapes
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Change over 13 days in Control and Drying treatment Fα values for ‘Thompson’ and ‘Flame’ grapes. Control Fα Drying treatment Fα
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‘Thompson’ Fα and weight loss (expressed in proportion to the initial value) over 13 days. The estimated weight loss value is a mean of three groups of grapes. Weight loss Fα ‘Thompson’ grape
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Comparison of weight loss changes and Fα changes in ‘Thompson’ grapes, using data from previous Fig. 0.80 = 20% wt. loss ‘Thompson’ grape
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‘Flame’ Fα and weight loss (expressed in proportion to the initial value) over 13 days. The estimated weight loss value is a mean of three groups of grapes. Weight loss Fα ‘Flame’ grape
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Comparison of weight loss changes and Fα changes in ‘Flame’ grapes, using data from previous Fig. 0.80 = 20% wt. loss ‘Flame’ grape
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CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial18.27683.06 13 d drying23.711303.03 Control (13 d in cold room) 15.37903.16 FlameInitial19.65163.08 13 d drying25.57003.10 Control (13 d in cold room) 17.85443.33 CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial 13 d drying Control (13 d in cold room) FlameInitial 13 d drying Control (13 d in cold room)
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CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial18.27683.06 13 d drying23.711303.03 Control (13 d in cold room) 15.37903.16 FlameInitial19.65163.08 13 d drying25.57003.10 Control (13 d in cold room) 17.85443.33 CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial18.2 13 d drying23.7 Control (13 d in cold room) 15.3 FlameInitial19.6 13 d drying25.5 Control (13 d in cold room) 17.8
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CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial18.27683.06 13 d drying23.711303.03 Control (13 d in cold room) 15.37903.16 FlameInitial19.65163.08 13 d drying25.57003.10 Control (13 d in cold room) 17.85443.33 CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial18.2768 13 d drying23.71130 Control (13 d in cold room) 15.3790 FlameInitial19.6516 13 d drying25.5700 Control (13 d in cold room) 17.8544
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CultivarTreatmentSSC (%) Tit. Acidity (mg/100 ml) pH ThompsonInitial18.27683.06 13 d drying23.711303.03 Control (13 d in cold room) 15.37903.16 FlameInitial19.65163.08 13 d drying25.57003.10 Control (13 d in cold room) 17.85443.33
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1. Introduction to chlorophyll fluorescence (CF) - CF curve – Fo, Fm, Fv = Fm-Fo - Identification of Fo as most important 2. Design of the HarvestWatch system - Produces Fα as an estimate of Fo - Important features of HarvestWatch system 3. Applications of HarvestWatch system - Control O 2 in CA stores - Monitor water loss in fruit, e.g. grapes 4. Concluding Remarks
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Concluding Remarks F is an estimate of Fo at zero irradiance F is very sensitive to water loss in grapes Change in F stops at ca. 20-25% water loss Changes in water loss in the field may be measurable by new FIRe fluorescence system Continuous and non-destructive F declines with water loss whereas it increases in low O 2
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