Fruit Quality of Beach Plum Samples Grown in the Northeast

1
Fruit Quality of Beach Plum Samples Grown in the
Northeast
2
Objectives

• To evaluate fruit quality and field variation
• To evaluate differences in total phenolic content
  (important for flavor)
• To measure antioxidant capacity (important for
  marketing)

3
Experimental Design

• 35 fruit samples from 4 different states (MA, NJ,
  NY, DE), 11 locations, wild and cultivated
• Two harvest seasons 2001 and 2002
• Physical and chemical evaluation

4
Materials

• Beach plum samples provided by Richard Uva from
  different locations in the Northeast including
  cultivated samples from Falmouth, MA
• Fresh fruits were analyzed for quality upon
  receiving
• Stored at -40oC for further chemical analysis

5
Methods

• Fruit quality analysis
• Fruit color Hunter colorimeter, color values
  L (lightness), a (red to green), and b
  (yellow to blue)
• pH pH meter
• Acid citric acid

6
Methods

• Soluble solids Brix
• Fruit size width, height, depth
• pulp manual pitting with a cherry pitter

7
Method-Extraction

• For chemical analysis, compounds extracted from
  the fruit
• Procedure followed based on Kalt et al. method
  (2001), with modifications

8
Method - Extraction
9
Method Chemical Analysis

• Total phenolic content measured using Folin
  Ciocalteu reagent (Singleton and Rossi, 1965)
• Gallic acid used as standard, absorbance read at
  750 nm, results expressed as mg of gallic acid
  equivalents per 100 g of fruit

10
Method Chemical Analysis Cont.

• Antioxidant capacity of water soluble compounds
  (ACW) measured using photochemiluminometer
  (PHOTOCHEM)
• The PHOTOCHEM uses a photochemiluminescence
  detection method
• Free radicals are generated with a
  photosensitizer and react with luminol to produce
  light, which is measured quantitatively

11
Method Chemical Analysis Cont.

• The intensity of the photochemiluminescence is
  attenuated as a function of antioxidant
  concentration
• Ascorbic acid used as standard, results expressed
  as equivalents of ascorbic acid in mg/100 g of
  fruit

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Photochem diagram
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Results

• Large variations per location in all the
  measurements.
• pH values ranged from 3.13 to 4.09.
• Size only width will be presented, the other 2
  values followed the same pattern.
• Color data not shown.

14
Results - reference

• Commercial plum varieties- used for fresh
  consumption or for prune making
• Soluble solids 12.8 - 29
• Total phenols 111 mg/100 g fruit
• Acids approx. 0.5 g/100 g fruit

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Beach PlumData shown by farm within the state
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Acid Content
17
Soluble Solids
18
Pulp Content
19
Fruit Size Width
20
Total Phenols
21
Antioxidant Capacity
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Results

• Cultivated samples from MA had the highest
  acidity.
• 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.
• Two samples had high phenol content, high
  antioxidant capacity, small size and low
  percentage pulp. Most phenolic compounds on skin.

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Conclusions

• Location (state and farm) and production practice
  did not seem to determine the fruit composition.
  2002 harvest will provide confirmation.
• Beach plum has significantly higher phenolic
  content than typical commercial varieties.
  Antioxidant capacity is likely to be also higher.

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Conclusions

• 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.
• Another phase of the project involves working
  with chefs to develop specialty products.

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Works Cited

• Singleton, V. L. Rossi, J. A., Jr. Colorimetry
  of total phenolics with phosphomolybdic-
  phosphotungstic acid reagents. Am. J. Enol.
  Vitic. 1965, 16, 144-158
• 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