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Author ORCID Identifier

https://orcid.org/0000-0003-0482-8182

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Food Science

Year Degree Awarded

2022

Month Degree Awarded

September

First Advisor

Eric A. Decker

Subject Categories

Food Chemistry

Abstract

Consumer interest in “clean” labels has continued to be a key driver of consumer behavior and purchasing habits over the past decade. Food manufacturers are therefore eager to replace synthetic antioxidants such as ethylenediaminetetraacetic acid (EDTA) with natural alternatives, however alternative chelators that will bind iron at low pH remain elusive. Coupled with the current oil shortages and supply chain challenges that have arisen recently, there is an urgent need for innovative solutions to increase the oxidative stability of edible oils. One available strategy is diluting oils high in unsaturated fatty acids into more stable, more saturated oils, thus delaying lipid oxidation by decreasing free-radical propagation reactions between oxidized fatty acids and unsaturated lipids. The effect of diluting fish oil into medium-chain triglycerides (MCTs) on oxidative stability was investigated using lipid hydroperoxides and gas chromatography headspace analysis. Dilutions up to 1 in 20 of fish oil in MCT extended propanal formation from 1 to 6 days in Tween-80-stabilized oil-in-water emulsions. This protective effect was not observed in emulsions wherein the two oils were in separate droplets. Fish oil blended with high oleic sunflower oil (HOSO) also demonstrated a protective effect when the oils were in the same emulsion droplets but not in separate emulsion droplets. The present study indicates that dilution can be used to increase the oxidative stability of polyunsaturated fatty acids in oil-in-water emulsions.

Another potential strategy relies on oxidized α-tocopherol being regenerated by phosphatidylethanolamine (PE). Although current commercial sources of PE are too expensive for use as a food additive, the present study aims to determine the optimal reaction conditions for generating high PE lecithin (MHPEL) enzymatically and to validate the MHPEL’s synergism with tocopherol in delaying lipid oxidation in an oil-in-water emulsion systems at pH 7, and 4, and in bulk oil. Under optimal conditions of pH 9.0, 37°C and 4h, a MHPEL with ~71.6% PE was obtained from 96% phosphatidylcholine lecithin using phospholipase D from Streptomyces chromofuscus. Compared to mixed tocopherols alone, the addition of MHPEL synergistically increased the both the hydroperoxide and hexanal lag phase of lipid oxidation in oil-in-water emulsions by 3 days in o/w emulsions at pH 7 and 3 and 2 days, respectively, at pH 4. In combination with 50 µmol/kg oil of α-tocopherol, the addition of 1000 µmol/kg oil MHPEL synergistically increased the lag phases by 5 and 4 days in bulk oil compared to tocopherol alone. The novel approaches contained herein represent potential clean-label strategies for increasing the oxidative stability of food systems and have strong potential for commercial applications to decrease food waste.

DOI

https://doi.org/10.7275/30807022

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