Document Type

Thesis - University Access Only

Award Date

2007

Degree Name

Master of Science (MS)

Department / School

Nutrition, Food Science, and Hospitality

Abstract

The North Central Region produces over 90% of all canola crop grown in United States and North Central Region canola production was 1.3 billion pounds in 2006. The sampling area consisted of Regions 1, 2 and 3 in the North Central growing region. The objectives of this study were to determine the variability of total phenolic content and antioxidant activity of canola crops grown in North Dakota counties (Region 1 and Region 2) and Minnesota counties (Region 3) for 2002 and 2003 years. The total phenolic content was measured using AOAC method (method# 952.03, 1990). Extraction protocols were optimized for canola samples. Antioxidant activity, the free radical scavenging effect of canola extracts, was measured using the 1, 1 diphenyl 2 picrylhydrazyl (DPPH) assay. Pure standards (tannic acid, quercetin, gallic acid and sinapic acid) were tested to allow easy interpretation of data and method validation. Total phenolic content ranged from 90.2 mg Tannic Acid Equivalents (T AE)/1 00g to 667 .1 mgT AE/1 00g and antioxidant activity ranged from 20.5% to 57.6% for the 2002 and 2003 crops. Quercetin used as an antioxidant activity reference yielded 91.9% antioxidant activity. While no significant correlation was found between total phenolic content and antioxidant activity for 2002 samples (N= 138), the two variables were highly correlated in the 2003 crop (N=l68). The coefficient determinations (R2) varied from 0.75 to 0.91 for 2003 crop. Phenolic compounds were responsible for most of the antioxidant activity in 2003 crop. Repeated day to day analyses of 5 samples (200 - 500 mgT AE/1 00g) on 5 different days demonstrated that the assays yielded excellent accuracy and precision over a range of analyte concentrations. Sinapine was determined to be the major phenolic compound in canola meal as measured by HPLC. Strong correlations (R2=0.86) were determined by sinapine concentration and total phenolic content (N=l8). Similar high coefficient of determination (R 2=0. 7 4) were noted between antioxidant activity and sinapine in the same samples. Sinapine may be used as a screening compound for total phenolic content determination in canola samples. Rapid means of sinapine may need to be investigated.

Library of Congress Subject Headings

Canola -- North Dakota
Canola -- Minnesota
Phenols
Antioxidants

Format

application/pdf

Number of Pages

112

Publisher

South Dakota State University

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