Food Science and Technology Department


First Advisor

Ozan N. Ciftci

Date of this Version



Vallecilla-Yepez, Lisbeth. (2017). Increasing cis-lycopene content of the oleoresin from tomato processing byproducts using supercritical carbon dioxide and assessment of its bioaccessibility. Dissertations, Theses, & Student Research in Food Science and Technology.


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 Professor Ozan N. Ciftci. Lincoln, Nebraska: December 2017

Copyright (c) 2017 Lisbeth Vallecilla Yepez


In recent years, health- and wellness-promoting foods have been one of the major focus of consumers; therefore, the food industry is increasing its efforts in developing these food products. Tomatoes, tomato-food products and their byproducts have gained special attention in virtue of the carotenoids-rich source that they represent, especially lycopene (~90%). The role of lycopene in human diet has been highlighted as a result of its direct relationship with the decrease of chronic diseases. Nevertheless, lycopene is water-insoluble making its extraction simple with organic-toxic solvents; in addition, lycopene degrades easily with light, time, and storage. Lycopene exist in nature mostly in trans-lycopene (~95%); however, cis-lycopene isomers provide potentially better health benefits than the trans-lycopene isomeric form due to their higher bioavailability.

The main objective of this thesis was to increase the bioaccessibility of the lycopene in the tomato oleoresin by SC-CO2 extraction. Specific objectives were to extract oleoresin from tomato processing byproducts, namely, tomato seed and peel, using SC-CO2 and optimize the extraction conditions for the highest cis-lycopene content, and to test the bioaccessibility of the SC-CO2-extracted lycopene in vitro.

The highest oleoresin yield (24.6%) was obtained from 100% seed blend with SC-CO2 extraction at temperature of 40 °C and pressure of 50 MPa, whereas the highest cis-lycopene content was achieved at temperature of 80 °C and pressure of 30 MPa from 100% peel. SC-CO2-extracted oleoresins contained 67% of cis-lycopene, while the hexane-extracted ones had 34%. When insoluble fraction was removed, the oil fraction contained up to 82% of cis-lycopene in SC-CO2 extracted oleoresins. SC-CO2 extraction increased the bioaccessibility of lycopene approximately 2-folds in the oleoresin and 2.4-folds in the oil fraction compared to hexane extraction (p2-extracted oleoresin. The bioaccessibility of the lycopene in the oil fraction was 1.7 and 4.0% for the hexane and SC-CO2-extracted oleoresins, respectively. Lycopene concentration in the digesta increased when the tomato oleoresin was used compared to oil fraction for both SC-CO2 and hexane extractions. After digestion of tomato peel oleoresin, lycopene concentration in the final digesta was 4.6 and 13.4 μg/g for hexane- and SC-CO2-extracted oleoresin, respectively. Oil fraction of the tomato peel oleoresin released concentrations of lycopene of 1.3 μg/g for hexane and 3.0 μg/g for SC-CO2 extracted oleoresin.

SC-CO2 can enhance the efficacy of lycopene during extraction stage in a simple and clean way. The use of cis-lycopene-rich extract from tomato processing byproducts in traditional foods can improve the functional properties of the product while adding value to the byproducts of the tomato industry processing industry.

Advisor: Ozan N. Ciftci