Title page for ETD etd-05012006-115234

Type of Document

Master's Thesis

Author

Yuan, Xianglong

Author's Email Address

xyuan3@lsu.edu

URN

etd-05012006-115234

Title

Evaluation on Antioxidant Activities of the Soybean Oils and Gums

Degree

Master of Science (M.S.)

Department

Food Science

Advisory Committee

Advisor Name	Title
Zhimin Xu	Committee Chair
Cristina M. Sabliov	Committee Member
Witoon Prinyawiwatkul	Committee Member

Keywords

antioxidant activity
tocopherol
phytosterol
soybean oil

Date of Defense

2006-04-05

Availability

unrestricted

Abstract

In this study crude soy oil was extracted from the soy flour by hexane solvent. The crude oil was refined using a refining procedure similar to the one in edible oil industries, which included degumming, neutralizing, and bleaching. As the result, the eight groups of the oils and the gums were obtained. The compositions of fatty acids and tocopherols in the eight groups of samples were analyzed using GC-FID and HPLC, respectively. The antioxidant activities of the samples were analyzed by two chemical models, cholesterol and DHA. The results showed that ã- and ä-tocopherols may not be the main antioxidants of the crude oil when studied by the two models. The analyses for the antioxidant activities indicated that gum-1 had the highest antioxidant activity among the samples. The gum-1 was fractionalized by a silica gel column and three fractions were obtained. The antioxidant activities of the fractions were analyzed by the cholesterol model. The result indicated that the ethyl acetate/hexane fraction had the highest activity among the fractions. The fraction was further analyzed and fractionalized by RE-HPLC using a two-step elution scheme. As a result, a RE-HPLC fraction containing two individual peaks was demonstrated higher antioxidant activity. A HPLC peak was identified as a phytosterol (plant cholesterol) by searching a GC-MS database.

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