Off-campus UMass Amherst users: To download campus access dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Dissertations that have an embargo placed on them will not be available to anyone until the embargo expires.

Author ORCID Identifier

https://orcid.org/0000-0002-6604-6525

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Food Science

Year Degree Awarded

2023

Month Degree Awarded

September

First Advisor

Eric A. Decker

Second Advisor

David J. McClements

Third Advisor

Jiakai Lu

Fourth Advisor

Pierre Villeneuve

Subject Categories

Food Chemistry

Abstract

Lipid oxidation results in off-flavors, toxic aldehydes, and co-oxidation of proteins and color compounds. Combining antioxidants to achieve synergistic interactions has been practiced for decades to improve oxidative stability. Nevertheless, synergism mechanisms have been poorly understood and rarely studied. This dissertation examines the mechanisms of antioxidant synergism in a model system with α-tocopherol (α-TOC) and myricetin (MYR). The interactions between α-tocopherol and taxifolin (TAX) were also tested because it has structural similarities to myricetin but has a higher redox potential. The first part of this research focused on the antioxidant interactions between α-tocopherol and myricetin in stripped soybean oil-in-water emulsions at pH 4.0 and pH 7.0. At pH 7.0, α-tocopherol: myricetin ratios of 2:1 and 1:1 yielded interaction indices of 3.00 and 3.63 for lipid hydroperoxides, and 2.44 and 3.00 for hexanal formation, indicating synergism. Myricetin's ability to regenerate oxidized α-tocopherol and slow its degradation was identified as the synergism mechanism. At pH 4.0, an antagonistic interaction was observed, which was associated with high ferric-reducing activity of myricetin in acidic environment. α-Tocopherol and taxifolin exhibited non-synergistic effects both in acidic and neutral emulsions. This was due to taxifolin's inability to recycle α-tocopherol at both pHs, unlike myricetin, and taxifolin's high ferric-reducing activity at pH 4.0, similar to myricetin. The second part of this research focused on antioxidant interactions between α-tocopherol and myricetin in stripped soybean oil. α-Tocopherol and myricetin ratios of 5:1, 2:1, 1:1, 1:2, and 1:5 resulted in interaction indexes of 1.14, 1.50, 1.55, 1.30, and 1.16, showing synergistic activity for both lipid hydroperoxide and hexanal formation. Synergism was also observed in phospholipid-containing bulk oils, both in the absence and presence of reverse micelles. α-Tocopherol and taxifolin, however, had additive effect at all antioxidant ratios. Antioxidant degradation results showed that myricetin delayed α-tocopherol oxidation, whereas taxifolin did not. These results revealed that myricetin's lower redox potential allowed it to cause synergism through regenerating oxidized α-tocopherol rather than by decreasing oxidation by metal chelation since both myricetin and taxifolin chelated iron. Thus, this study advises combining α-tocopherol with myricetin in bulk oils and neutral oil-in-water emulsions to improve oxidative stability and reduce food waste.

DOI

https://doi.org/10.7275/35954953

Download

Share

COinS