Graduation Year

2024

Document Type

Thesis

Degree

M.S.C.H.

Degree Name

MS in Chemical Engineering (M.S.C.H.)

Degree Granting Department

Chemical, Biological and Materials Engineering

Major Professor

Norma Alcantar, Ph.D.

Committee Member

Yogi Goswami, Ph.D.

Committee Member

Anna Pyayt, Ph.D.

Keywords

2-Methylisoborneol, Geosmin, Natural Absorbents, Sustainable Solutions, Economic Impact

Abstract

Aquaculture has become a vital component of global food production, now providing 50% of the world's fish supply. However, the industry encounters major challenges due to off-flavor compounds like Geosmin and 2-Methylisoborneol (MIB), which give fish an unpleasant earthy or musty smell. These compounds are detectable by humans at extremely low levels 0.7 parts per billion (ppb) for MIB and ten parts per trillion (ppt) for Geosmin—making them a persistent problem. Their presence not only reduces the sensory quality of aquaculture products but also results in significant economic losses, with U.S. catfish production incurring an additional $15–$23 million annually due to extensive purging processes.

Traditional methods to address these off-flavors, such as purging fish in clean water, are both expensive and labor-intensive, highlighting the need for more efficient and cost-effective solutions. This research investigates the potential of cactus mucilage extracts from the Opuntia Ficus-indica cactus, specifically the Non-gelling Extract (NE) and Gelling Extract (GE), as innovative solutions for absorbing Geosmin and MIB in aquaculture systems.

A unique aspect of this study involves using NE and GE extracts as a placebo within sodium alginate beads to assess their absorption capabilities. These natural extracts were incorporated as placebo components to simulate and enhance the beads' absorption properties. To evaluate their effectiveness, NE and GE extracts were initially assessed with Methylene Blue dye at a concentration of 4 ppm. Methylene Blue served as a model compound to mimic the conditions for Geosmin and MIB absorption in aquaculture environments.

Preliminary results showed that sodium alginate beads containing NE and GE extracts demonstrated promising absorption capabilities, indicating their potential as effective natural absorbents for Geosmin and MIB. By using these extracts as placebo components within the beads, this research presents a sustainable and cost-effective alternative to traditional off-flavor mitigation methods. Successful application of this approach could significantly lower the costs and environmental impact of current purging techniques, offering a transformative solution for the aquaculture industry. This study addresses the immediate issue of off-flavors while also contributing to sustainability and improved economic returns in aquaculture.

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