Date of Award

5-2014

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Mary Ellen Camire

Second Committee Member

Balunkeswar Nayak

Third Committee Member

Lewis Brian Perkins

Abstract

Antioxidants in food are believed to play a role in maintaining good health, and this study continues the investigation of alternative plant sources. Equisetum arvense (horsetail) grows abundantly in Maine and in many other states. Horsetail has a tradition of usage for health benefits, and modern scientific investigations have shown some chemical compounds of interest. Of particular interest in the current work are the phenolic compounds and flavonoids. Microwave and advanced solvent extraction (ASE), using ethanol in water as the extraction solvent, were assessed for their effectiveness in extracting these compounds using a methanol extraction as a standard. The effect of temperature on the extraction was also measured. The antioxidant properties of the extracts were measured by the Folin-Ciocalteau total phenolics assay and also by the oxygen radical absorbance capacity (ORAC) assay. Total phenolic values were highest for the ASE extraction at 130°C with a value of 1376 mg gallic acid equivalent (GAE) per 100 g of dried plant material, and 1309 mg GAE per 100 g for microwave extraction. ORAC assay values peaked at 40138 μmol Trolox equivalent (TE) per 100 g for ASE extracts and 39,389 μmol TE per 100 g for microwave extracts, with these figures also being achieved at 130°C. The results for the microwave and ASE extracts compared favorably with those of the methanol extracts, and this shows the capability of those modern extraction methods. Liquid chromatography was used in an attempt to further investigate the profile of compounds in the extracts. Some concerns still remain over the suitability of horsetail as a source of these compounds due to the believed presence of toxic and irritant compounds. Suitable manufacturing procedures may easily overcome these concerns and allow the future development of a commercial product from horsetail.

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