Presentation on theme: "Fruit Quality of Beach Plum Samples Grown in the Northeast."— Presentation transcript:
Fruit Quality of Beach Plum Samples Grown in the Northeast
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)
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
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 -40 o C for further chemical analysis
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
Methods Soluble solids: °Brix Fruit size: width, height, depth % pulp: manual pitting with a cherry pitter
Method-Extraction For chemical analysis, compounds extracted from the fruit 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 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
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
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
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.
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
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.
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.
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.
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