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Total Phenolic Content Variation_ Antioxidant Capacity_ And Frui

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					Fruit Quality of Beach Plum
Samples Grown in the
Northeast
Objectives
n To evaluate fruit quality and field
  variation
n To evaluate differences in total
  phenolic content (important for
  flavor)
n To measure antioxidant capacity
  (important for marketing)
Experimental Design
n   35 fruit samples from 4 different states
    (MA, NJ, NY, DE), 11 locations, wild and
    cultivated
n   Two harvest seasons: 2001 and 2002
n   Physical and chemical evaluation
Materials
n   Beach plum samples provided by
    Richard Uva from different locations
    in the Northeast including cultivated
    samples from Falmouth, MA
n   Fresh fruits were analyzed for quality
    upon receiving
n   Stored at -40oC for further chemical
    analysis
 Methods
Fruit quality analysis
n   Fruit color: Hunter colorimeter,
  color values ‘L’ (lightness), ‘a’ (red
  to green), and ‘b’ (yellow to blue)
n   pH: pH meter
n   Acid: % citric acid
    Methods
n  Soluble solids: °Brix
n  Fruit size: width, height, depth
n  % pulp: manual pitting with a
  cherry pitter
Method-Extraction
n   For chemical analysis, compounds
    extracted from the fruit
n   Procedure followed based on Kalt et al.
    method (2001), with modifications
Method - Extraction

                       7 g pitted fruit
                       20 ml methanol
Homogenized 2 min
            Incubated 18 hr, dark

                          Centrifuged 15,000 rpm,
                                   15 min
                                             Supernatant
                                               analyzed
Method – Chemical
Analysis
n   Total phenolic content measured using
    Folin Ciocalteu reagent (Singleton and
    Rossi, 1965)
n   Gallic acid used as standard,
    absorbance read at 750 nm, results
    expressed as mg of gallic acid
    equivalents per 100 g of fruit
    Method – Chemical
    Analysis Cont.
n   Antioxidant capacity of water soluble
    compounds (ACW) measured using
    photochemiluminometer (PHOTOCHEM)
n   The PHOTOCHEM uses a
    photochemiluminescence detection method
n   Free radicals are generated with a
    photosensitizer and react with luminol to
    produce light, which is measured quantitatively
Method – Chemical
Analysis Cont.
n   The intensity of the
    photochemiluminescence is attenuated
    as a function of antioxidant
    concentration
n   Ascorbic acid used as standard, results
    expressed as equivalents of ascorbic
    acid in mg/100 g of fruit
Photochem diagram
Results
n   Large variations per location in all the
    measurements.
n   pH values ranged from 3.13 to 4.09.
n   Size: only width will be presented, the
    other 2 values followed the same
    pattern.
n   Color data not shown.
Results - reference
n   Commercial plum varieties- used for
    fresh consumption or for prune
    making
    n   Soluble solids 12.8 - 29%
    n   Total phenols 111 mg/100 g fruit
    n   Acids approx. 0.5 g/100 g fruit
Beach Plum

Data shown by farm
within the state
Acid Content
Soluble Solids
Pulp Content
Fruit Size: Width
Total Phenols
Antioxidant Capacity
Results
n   Cultivated samples from MA had the highest
    acidity.
n   A few samples had high Brix, lower acidity
    and relatively low phenol content. Potential
    for fresh market or minimally processed foods
    due to milder flavor.
n   Two samples had high phenol content, high
    antioxidant capacity, small size and low
    percentage pulp. Most phenolic compounds
    on skin.
    Conclusions
n   Location (state and farm) and
    production practice did not seem to
    determine the fruit composition. 2002
    harvest will provide confirmation.
n   Beach plum has significantly higher
    phenolic content than typical
    commercial varieties. Antioxidant
    capacity is likely to be also higher.
Conclusions
n   The high phenolic content and high
    acidity restrict the use of the fruit to
    processed products where blending
    and dilution are used to counteract
    the effect.
n   Another phase of the project
    involves working with chefs to
    develop specialty products.
Works Cited
n   Singleton, V. L.; Rossi, J. A., Jr. Colorimetry of total
    phenolics with phosphomolybdic- phosphotungstic
    acid reagents. Am. J. Enol. Vitic. 1965, 16, 144-158
n   Kalt, W.; Ryan D. A. J.; Duy, J. C.; Prior, R. L.;
    Ehlenfeldt, M. K.; Kloet, S. P. V. Interspecific
    Variation in Anthocyanins, Phenolics, and
    Antioxidant Capacity among Genotypes of Highbush
    and Lowbush Blueberries (Vaccinium Section
    cyanococcus spp.). J. Agric. Food Chem. 2001, 49,
    4761-4767

				
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posted:7/16/2013
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