Date of Award

Spring 5-13-2017

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Angela D. Myracle

Second Committee Member

Mona Therrien

Third Committee Member

Renae Moran

Abstract

Prunus salicina Lindl., or Japanese plums, are naturally rich in fiber, vitamins, minerals, and phytonutrients. Consumption of plums can be part of a healthy diet, and can contribute to an overall increased fruit intake at low caloric cost to consumers. Through the local production of plums, harvesting can be done without concern for cross-country shipping helping to increase both consumer acceptance and nutrition quality.

The first objective of this study was to determine consumer acceptance of locally grown plum cultivars at two stages of ripeness: Mature and Tree-ripe. Sensory testing was conducted in the Sensory Evaluation Center at the University of Maine on plum cultivars grown at Highmoor Farm located in Monmouth, ME. The highest likeness ratings for ‘overall’ acceptability was attained by Tree-ripe stage for Spring Satin, Oblinaja, and Abundance with 7.28 ± 1.57, 7.13 ± 1.57, 7.02 ± 1.38 respectively. In similar consumer studies, the fruit was deemed to be consumer acceptable with a likeness rating of >5.0; all cultivars tested surpassed this value. The predictive abilities of the Brix:TA were not conclusive for this study. Methley, the cultivar with the lowest overall likeness rating for both Tree-ripe 5.98 ± 1.77 and Mature 5.96 ± 1.88, had a Brix:TA greater than that of Oblinaja at 8.56 ± 0.15 and 5.56 ± 0.15 respectively. Choosing cultivars based solely on a single characteristic may be presumptuous, as attributes such as mouth feel can be just as important as taste and flavor.

The second objective of this study was to evaluate essential nutrient and phytochemical content. Phytochemical constituents were extracted using acidified methanol for eight locally grown plum cultivars at two stages of ripeness (n=15). Total monomeric anthocyanin, ascorbic acid (AA), total phenolics, and free radical scavenging ability were measured. Spring Satin Tree-ripe had the greatest anthocyanin content 301.71 ± 9.32 mg /100g and AA content 78.75 ± 6.25 mg /100g. Toka Mature had the greatest antioxidant capacity, demonstrating 50% inhibition of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) 0.781 ± 0.06 mg/mL. Total phenolic content was highest in Toka Mature 1379.23 ± 24.67 mg/100g. Statistically significant differences were found for bioactives between stages of ripeness, although, there were no consistent trends for either Mature or Tree-ripe stages having the greater bioactive constituent levels.

Plum cultivars that can withstand Maine winters were successfully cultivated and widely accepted by local consumers. Cultivation of plums that are well liked by consumers can provide a new agricultural sector for Maine farmers. Consumer testing is a relatively low-cost investment for farmers that can help provide valuable information on what cultivars to incorporate into their growing program. This research contributes to fill the gap in the market and justify that Spring Satin, Oblinaja, and Abundance have great marketing potential for tree-fruit growers.

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