Food Science and Technology Department


First Advisor

Dr. Yue Zhang

Second Advisor

Dr. Ozan N. Ciftci

Date of this Version


Document Type



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Food Science and Technology, Under the Supervision of Professors Yue Zhang and Ozan N. Ciftci. Lincoln, Nebraska: April, 2019

Copyright 2019 Liyang Xie


Astaxanthin is a high-value carotenoid widely used in the food, feed, nutraceutical, and pharmaceutical industries. Natural sources of astaxanthin are preferable to synthetic sources. However, current sources of natural astaxanthin are limited and fall short of global demand. In addition, effective extraction and stabilization strategies are needed before the utilization of natural astaxanthin in food applications. This work investigated 1) the feasibility of ethanol-modified supercritical carbon dioxide (SC-CO2) extraction of astaxanthin from engineered camelina seed, a potential source of natural astaxanthin, and 2) the potential of an emulsion-based system to protect astaxanthin after extraction. The physical properties of the emulsion were characterized, and the protection of astaxanthin by emulsion was evaluated.

The results from the extraction project indicated that ethanol-modified SC-CO2 was a feasible green extraction technique to extract astaxanthin from a high oil, low water content material. In comparison to other techniques, ethanol-modified SC-CO2 was found to be more effective than accelerated ethanol extraction or accelerated hexane extraction, and as effective as hexane at extracting astaxanthin from engineered camelina seed. As opposed to hexane-based extractions, ethanol-modified SC-CO2 can generate products that are compliant with clean labeling. An emulsion system made by egg albumin (EA) and gum arabic (GA) with and without tannic acid cross-linking were used to inhibit the effects of UV light and heat on astaxanthin. Compared to oil from non-engineered camelina seed oil, engineered camelina seed oil had higher antioxidant activity, which can be further improved by tannic acid crosslinking. The EA/GA- stabilized emulsion with tannic acid crosslinking was able to better protect astaxanthin against UV light and heat, and therefore further broaden the food applications of astaxanthin-enriched camelina oil.

Optimized ethanol-modified SC-CO2 can be used for efficient recovery of astaxanthin from the engineered camelina seed. The EA/GA- stabilized astaxanthinenriched emulsion product may be used as a food ingredient in various food applications.

Advisors: Yue Zhang and Ozan N. Ciftci