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Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Food Science

Year Degree Awarded

2017

Month Degree Awarded

May

First Advisor

Eric Decker

Subject Categories

Food Chemistry

Abstract

Consumer concern over synthetic food antioxidants have led researchers to seek alternative natural, or ‘clean’ label, solutions to prevent lipid oxidation. Unfortunately, natural antioxidants are often not as effective as their synthetic counterparts. As a result, there remains a need to develop active packaging strategies and maximize current antioxidant strategies in food applications.

Active packaging, or packaging that has a function beyond being an inert barrier, is an attractive strategy to limit lipid oxidation in foods. Active packaging performs the work of an antioxidant without appearing on the package label. The work presented here builds upon active packaging development as a means to control prooxidant metals in oil-in-water (O/W) emulsions. A metal-chelating active packaging material was designed and characterized, in which biomimetic poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of a common industry used plastic, poly(ethylene terephthalate) or PET. Surface characterization of the plastic film by spectroscopy and scanning electron microscopy (SEM) revealed successful grafting and conversion of the plastic to contain metal chelating group on the surface. Metal analysis and lipid oxidation studies demonstrated the activity of the PHA grafted PET films to inhibit metal-promoted oxidation in acidified O/W emulsions.

Oxygen removal from food packaging is another practical solution to stabilize foods without additives. Indeed, manufacturers have been using this technique for decades, however there is little evidence to how much oxygen needs to be removed to provide meaningful increases in oxidative stability. Results from this research suggest that the oxidative stability of 1% O/W emulsions can be extended by reducing system oxygen by ~58%, but to have a meaningful antioxidant impact greater than ≥93% oxygen removal is required. Further investigation into simulated commercial oxygen removal strategies (e.g., nitrogen displacement of oxygen and ascorbic acid) demonstrated that current industrial strategies are lacking and need to be optimized in order to enhance stability against lipid oxidation.

Incorporating both strategies, active packaging and oxygen removal, a commercial oxygen scavenging packaging was tested in its ability to reduce packaged oxygen, inhibit lipid oxidation in O/W emulsions, and stabilize oxygen-sensitive vitamins. Dissolved and headspace oxygen measurements determined the material’s ability to scavenge >95% system oxygen across conditions such as pH, sodium chloride, and fat content. Active oxygen scavenging packaging was able to inhibit lipid oxidation in O/W emulsions as well as preserve Vitamin E and Vitamin C in model solutions. This work demonstrates that active packaging and oxygen reduction are promising strategies that warrant more research in their ability to help achieve ‘clean label’ solutions to prevent lipid oxidation in foods.

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