Location: Food Processing and Sensory Quality Research
2025 Annual Report
Objectives
The objective of this research project is to stimulate consumer demand for U.S. farm raised catfish products and increase the profitability of the Catfish Industry through improved product quality.
Approach
By improving methodology for detecting the presence of off-flavor compounds in farm raised catfish, fewer off-flavor fish should reach the consumer, resulting in an increased demand and market share for U.S. farm raised catfish. To improve quality, this project will assess and provide feedback to individual catfish processing plants on the proportion of fish with off-flavors, passing through their plant and will work directly with these plants to control off-flavor issues at the plant. Additionally, current methods for mitigating off-flavors are primarily pre-harvest approaches, and can be costly, time consuming and increase fish stress. Post-harvest research is proposed to treat mildly off-flavored fillets with weak acids and marinades to mitigate the off-flavor compounds and expand the catfish line of products. Furthermore, methods for improving shelf life of fresh and frozen fillets will be examined using UV-C light, and vacuum packaging. Research proposed here will enable the existing U.S. Catfish Industry to better control quality, provide new co-products and improve shelf life.
Progress Report
This is the final report for project 6054-43440-051-00D.In support of Objective 1, Agricultural Research Service (ARS) scientists at New Orleans,Louisiana investigated how swim speed affects off-flavor purging in fish. As part of a Materials Transfer Agreement with the Conservation Fund, researchers completed fish sampling and submitted a manuscript to Aquaculture Engineering. In related work, researchers evaluated a novel water purification system that reduced 2-methylisoborneol (MIB) and geosmin concentrations from 60 nanograms per liter to near-undetectable levels in an 18 cubic meter static tank, cutting salmon purging time in half. These advances offer fish farmers faster and more efficient ways to improve product quality and reduce time to market, helping maintain profitability and consumer satisfaction.
Researchers also improved analytical tools for measuring off-flavors. They implemented a solid-phase microextraction (SPME) Arrow system with greater adsorbent capacity, which enhanced detection sensitivity. They developed and validated a stable isotope dilution method to quantify MIB and geosmin in fish fillets with improved accuracy and throughput compared to microwave distillation. This method allowed up to 20 samples to be processed simultaneously while reducing labor and material use. These improvements can help processors better monitor and control off-flavors in fish, ultimately leading to a more consistent product for consumers.
To support future sensory research, scientists developed a controlled spiking method using vegetable oil to introduce geosmin into raw fish fillets. These methods enabled production of test samples with known concentrations of off-flavor compounds, advancing sensory training and lexicon development. In the future, these tools will help producers train quality control staff and communicate flavor expectations more clearly to buyers and consumers.
Over the five-year period, researchers designed and executed a multi-phase effort to define consumer sensory thresholds for geosmin. In 2022 and 2023, ARS scientists collaborated with industry partners to conduct controlled feeding trials in rainbow trout, reaching fillet concentrations of up to 2,000 parts per trillion of geosmin. A series of sensory panels with 132 consumers showed that racemic geosmin, which is an equal mixture of two versions of the same molecule that are mirror images of each other, did not significantly affect aroma, flavor, or acceptability at levels up to 600 parts per trillion. This suggests that future research should use more aroma-active isomers and not racemic mixture in future testing. This work provides science-based thresholds to guide producers on when mitigation is necessary and when mild off-flavors may not impact consumer preference, reducing unnecessary costs.
Simultaneously, ARS scientists carried out a multiregional consumer study to develop a standardized lexicon for describing geosmin-related off-flavors in water and fish. Between 2022 and 2024, researchers collected and analyzed data from nearly 500 consumers across Louisiana, New Jersey, and Ohio. Results showed that descriptors like “earthy” were most common, though regional and language-based differences were notable. These findings inform more effective product labeling, quality assurance, and communication strategies, ultimately helping producers better tailor their products to regional markets and consumer expectations.
In support of Objective 2, ARS scientists collaborated with Louisiana State University to evaluate consumer attitudes toward seafood byproduct utilization. They conducted surveys with over 1,600 consumers. The first survey in 2022 indicated preferences for byproduct use in other seafood applications, followed by seasoning mixes, sauces, and dressings. The second survey in 2025 explored how emotions and safety messaging influenced trial intent. These insights help processors, policymakers, and seafood companies better understand how to market value-added products from what would otherwise be waste, benefiting the bottom lines.
Researchers developed and tested new food products from seafood byproducts. They created a calcium-rich catfish bone powder for use in breading mixes. Consumer studies showed that incorporating up to 20 percent bone powder into fried catfish did not reduce acceptability and actually improved purchase intent when paired with educational messaging. This innovation creates a new use for underutilized byproducts, improving processor yields and giving consumers healthier, functional food choices.
ARS scientists also partnered with a tribal seafood processor to create smoked catfish fillets and bellies using dry and wet brining. Initial taste tests with 70 consumers found 75 percent expressed positive purchase intent for wet-brined products. Researchers optimized processing and scaled up production. Consumer and expert testing panels were developed for broader market evaluation in the Pacific Northwest and Alaska. These smoked products offer fish farmers new ways to sell undervalued cuts like catfish bellies, increasing market diversification and revenue.
Researchers also explored methods to extend the shelf life of fresh catfish fillets. They tested low doses of germicidal ultraviolet-C (UV-C) light and found significant bacterial reductions without compromising appearance or quality. The effects lasted for up to six days in refrigeration. Additional studies showed variation in treatment effectiveness due to fillet properties. ARS initiated collaborations to combine UV-C with packaging methods for greater consistency. These findings give processors new options to maintain product freshness, reduce spoilage, and meet market demands, which are all benefits that can improve profits and consumer confidence in aquaculture products.
Finally, researchers examined whether weak acids could degrade geosmin and MIB in post-harvest catfish. While strong acid conditions degraded these compounds, they were not suitable for food use. Results suggest that improvements in citrus-treated catfish are due to flavor masking, not compound breakdown. This knowledge helps processors avoid ineffective treatments and focus on practical flavor solutions that maintain safety and quality.
This project significantly advanced understanding of off-flavor development and mitigation in aquaculture, improved analytical and sensory tools, and supported new product innovation using seafood byproducts. The results provided benefits to fish farmers by improving quality control and reducing waste, while offering consumers more flavorful, viable, and nutritious seafood choices.
Accomplishments