fruit quality

8/6/2019 Fruit Quality

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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

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