Date of Award

5-2014

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

Balunkeswar Nayak

Abstract

Maine is the leading producer of wild blueberries (Vaccinium angustifolium Ait.) worldwide. In the United States, blueberries are the second most valuable berry crop. Nearly 20% of blueberries produced in the U.S. are sourced from Maine wild blueberry farms. In 2012, the value of Maine wild blueberries reached nearly 69.1 million dollars. Blueberries are rich in phytochemicals and well known for the health benefits associated with their non-nutritive composition. Wild blueberries are native to Maine and resilient to local environmental stresses. Despite their adaptation to extreme conditions, the commercial success of wild blueberry crops relies on efficient management practices. Organic agriculture and Integrated Crop Management (ICM) have been adopted in Maine due to consumer demand for an ecologically sustainable and socially acceptable food supply. Variations in agricultural input, however, can influence wild blueberry characteristics.

Under the USDA Specialty Crops Research Initiative, this research compared the effects of various agricultural inputs on the sensory quality and chemical composition of Maine wild blueberries. The comparison of high, medium, low and organic management inputs for Maine lowbush blueberries will help generate recommendations for growers to efficiently and sustainably utilize farming resources while maximizing berry quality.

Blueberry samples were harvested from sixteen farms throughout Maine with four farms designated for each treatment group to capture the diverse nature of wild blueberries. Representative samples from each lot were winnowed, hand-sorted and stored at 4°C in preparation for analysis. Ten gram samples were extracted with 70% acetone acidified with 0.1% HCl. The blueberry extracts were then diluted and randomized for total phenolic and anthocyanin content and antioxidant capacity analysis using Folin-Ciocalteu, pH differential, and Oxygen Radical Absorbance Capacity (ORAC) assays, respectively. Consumers (N = 50) rated the blueberries for appearance, color, size, flavor, texture, and overall acceptability using a 9-point hedonic scale. ANOVA, Tukey’s HSD and Pearson correlation statistical analysis’ were used to compare treatment means.

Agricultural inputs at low and organic levels produced the highest total phenolic content, anthocyanin content and antioxidant capacity. High input blueberries received significantly lower ratings for flavor, size and overall acceptability than did other treatments. Consumers rated the low and medium input blueberries higher than the high input samples for appearance. There were no significant differences in texture or color. Hedonic ratings were greater than 7 (like moderately) in all categories for the organic, low and medium input blueberries. In conclusion, low and organic input may produce blueberries with comparable sensory quality to medium input berries and a more desirable chemical composition, but these results were only observed in the second crop cycle of this four year study. Therefore, recommendations to growers highlight the possibility of high quality Maine wild blueberries produced from a medium agricultural input level, which was seen in both production cycles. Further research regarding the effect of low and organic growing systems on sensory quality and chemical composition may be useful to identify trends.

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