Date of Award

5-2012

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Mary Ellen Camire

Second Committee Member

David Yarborough

Third Committee Member

Alfred Bushway

Abstract

Maine wild lowbush blueberries (Vaccinium angustifolium Ait.) are economically and nutritionally important. According to the University of Maine's Cooperative Extension blueberry specialist, David Yarborough, the 2008 wild blueberry harvest contributed $172 million to Maine's economy. Modern crop management has increased the productivity and success of the wild blueberry harvest. Using Integrated Crop Management (ICM) and Integrated Pest Management (IPM), the growers are able to control insects and diseases that might reduce production. Although wild blueberries are indigenous to Maine and thus are naturally more resistant to native insects, there are other challenges that face the blueberry plants. Winter injury, drought, and disease are just some of the unpredictable issues that growers encounter. The ICM and IPM systems have helped reduce pesticide residues. However, organic foods and farming methods are a growing trend and more consumers are interested in this practice as it is believed to be a safer alternative to conventional agriculture. The impact of changing agricultural practices on phytochemicals and sensory quality must be identified before alternative practices are recommended to growers. Our objectives of this study were to determine the effects of three levels of conventional agrochemical input (high, medium, and low) versus organic production, with and without mulch, on phytochemical content, antioxidant capacity, and sensory acceptability of wild blueberry fruit.

Two different sites were harvested for each of the treatments to encompass the natural genetic diversity in this wild crop. Blueberries were harvested, winnowed, and sorted into 10 g samples. Cold extraction using 85% methanol began 24 hr after harvest, and was completed 24 hr after initial extraction. Extracts were then diluted according to assay specifications and randomized. Folin-Ciocalteu, pH differential, and ORAC assays measured phytochemical content and antioxidant capacity. Fifty consumers evaluated blueberries using a 9-point hedonic scale for appearance, color, size, flavor, texture, and overall acceptability. ANOVA and Tukey's HSD were used for statistical analyses.

The low input treatment had significantly higher ORAC and total phenolic content (p< 0.05), but anthocyanin content did not differ among treatments. Low input berries received lower hedonic ratings for appearance, size and overall acceptability compared with berries from high- and medium-input plots. Organic berries were also liked less for their small size compared with the higher-input treatments. Medium-input berries were not different from either organic treatment in flavor or overall acceptability. Anthocyanin, phenolic and ORAC content were negatively correlated with overall acceptability. These results suggest that an increase in agronomic input does not translate to increases in blueberry phytonutrient content or quality.

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