fruit quality
TRANSCRIPT
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Fruit Quality of Beach PlumSamples Grown in theNortheast
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Objectives
To evaluate fruit quality and fieldvariation
To evaluate differences in totalphenolic content (important forflavor)
To measure antioxidant capacity(important for marketing)
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Experimental Design 35 fruit samples from 4 different states
(MA, NJ, NY, DE), 11 locations, wild andcultivated
Two harvest seasons: 2001 and 2002
Physical and chemical evaluation
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Materials
Beach plum samples provided byRichard Uva from different locations
in the Northeast including cultivatedsamples from Falmouth, MA
Fresh fruits were analyzed for quality
upon receiving Stored at -40oC for further chemical
analysis
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MethodsFruit quality analysis
Fruit color: Hunter colorimeter,color values L (lightness), a (redto green), and b (yellow to blue)
pH: pH meter
Acid: % citric acid
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Methods
Soluble solids: Brix
Fruit size: width, height, depth % pulp: manual pitting with a
cherry pitter
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Method-Extraction For chemical analysis, compounds
extracted from the fruit
Procedure followed based on Kalt et al.method (2001), with modifications
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Method - Extraction
7 g pitted fruit
20 ml methanol
Homogenized 2 min
Incubated 18 hr, dark
Centrifuged 15,000 rpm,
15 min
Supernatantanalyzed
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Method Chemical
Analysis
Total phenolic content measured usingFolin Ciocalteu reagent (Singleton andRossi, 1965)
Gallic acid used as standard,absorbance read at 750 nm, results
expressed as mg of gallic acidequivalents per 100 g of fruit
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Method Chemical
Analysis Cont. Antioxidant capacity of water soluble
compounds (ACW) measured usingphotochemiluminometer (PHOTOCHEM)
The PHOTOCHEM uses aphotochemiluminescence detection method
Free radicals are generated with a
photosensitizer and react with luminol toproduce light, which is measured quantitatively
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Method Chemical
Analysis Cont.
The intensity of thephotochemiluminescence is attenuatedas a function of antioxidantconcentration
Ascorbic acid used as standard, results
expressed as equivalents of ascorbicacid in mg/100 g of fruit
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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, theother 2 values followed the same
pattern. Color data not shown.
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Results - reference Commercial plum varieties- used for
fresh consumption or for prunemaking
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 Plum
Data shown by farmwithin the state
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Acid Content
0
0.5
1
1.5
2
2.5
3
3.5
Barnstable
MA
Barnstable
,
Barnstable
,
Barnstable
,
Barnstable
,
Falm
outh
Falm
outh
Falm
outh,
Falm
outh,
Falm
outh,
Falm
outh,
Falm
outh,
Falm
outh
Falm
outh,
Falm
outh,
Falm
outh,
Sandwich
,
East
Sandwich,
East
Sandwich,
Newbu
ryport,
Westport,
Westport,
Mattituck
,
Mattituck
Mattituck
,
Montauk
Cape
May
Cape
May
Atsion
NRCS
NRCS
Beach,
Location
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Total Phenols
0
100
200
300
400
500
600
700
800
Location
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Antioxidant Capacity
0
50
100
150
200
250
300
350
400
450
500
Bar
nstabl
e,MA
Location
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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. Potentialfor fresh market or minimally processed foodsdue to milder flavor.
Two samples had high phenol content, high
antioxidant capacity, small size and lowpercentage pulp. Most phenolic compoundson skin.
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Conclusions
Location (state and farm) andproduction practice did not seem to
determine the fruit composition. 2002harvest will provide confirmation.
Beach plum has significantly higherphenolic content than typicalcommercial varieties. Antioxidantcapacity 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 blendingand dilution are used to counteractthe effect.
Another phase of the projectinvolves working with chefs todevelop specialty products.
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Works Cited
Singleton, V. L.; Rossi, J. A., Jr. Colorimetry of totalphenolics 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. InterspecificVariation in Anthocyanins, Phenolics, andAntioxidant Capacity among Genotypes of Highbush
and Lowbush Blueberries (Vaccinium Sectioncyanococcus spp.). J. Agric. Food Chem. 2001, 49,4761-4767