Research Project: Improving the Product Value of Catfish

Location: Food Processing and Sensory Quality Research

2018 Annual Report

Objectives
The overall goal of this research project is to stimulate consumer demand for catfish products, and increase the profitability of the catfish industry by improving product quality and developing greater utilization of catfish byproducts. To achieve this overall goal we will pursue the following objectives: Objective 1: Characterization of off-flavors and color in catfish and, Objective 2: Enhance the utilization of byproducts from aquaculture product processing.

Approach
The approach objective 1 research will evaluate the incidence and diversity of off-flavors and fillet color in hybrid and channel catfish throughout the year across several locales. This information will be useful in devising new strategies to improve the quality of products entering the market place by reducing the incidence of off-flavor and color variation in catfish products. In addition, improved methods for determining the incidence of off-flavors prior to harvest would be developed. The approach for objective 2 higher valued products can be made from some catfish processing byproduct components. This research will identify and quantify the composition of the catfish processing byproduct streams and its seasonal variation. This information will be used to identify opportunities to add value to selected byproduct components.

Progress Report
Progress was made on the two objectives and their sub objectives, all of which fall under National Program 106, Aquaculture, Component 5, Product Quality and New Products. Progress on this project focuses on meeting research needs that include: 1) developing methods to measure quality attributes such as off-flavor, color, and firmness; 2) evaluating the effects of different production systems on these quality parameters and identifying production systems that optimize product quality and uniformity, and 3) developing economical methods to collect, preserve and store valuable by-products from fish processing waste until they can be further processed into value added products. Under Objective 1, characterization of off-flavors and color in catfish, we made significant progress in determine if there are specific regions of a fillet that bioaccumlate the off-flavor compounds. Results indicated that although certain areas tended to have a higher concentration of off-flavor compounds than the average off flavor values, a specific optimal spot could not be identified. Therefore, the recommendation for the flavor checker at the processing plants is to sample the fish at two or more areas if no off-flavor is detected in the first spot. Significant progress was also made on Objective 1 by ARS researchers in New Orleans, Louisiana, developing a new method for measuring the texture of cooked catfish fillets. Catfish texture is important to consumers, especially if the texture does not meet consumer expectations for uniform product hardness and mouthfeel characteristics. Texture problems with catfish fillets include soft or mushy texture and occasional fillets that are too firm. To evaluate catfish texture quality it is more economical and faster to use instrumental methods for monitoring texture than evaluations using a sensory panel. In this project, a descriptive trained sensory texture panel evaluated both fresh frozen and individually quick frozen catfish fillets, and results were compared to a method ARS researchers developed for mechanical analysis of catfish texture. The goal was to have a mechanical method for determining catfish fillet texture that would correlate with sensory evaluation of fillet texture. Predictive equations were developed for sensory texture evaluation and the mechanical evaluation method. Results indicated that mechanical evaluation was more successful for identifying differences between individually frozen fillets and fresh frozen fillets. The new mechanical evaluation method can be used in processing plants as part of their quality control program. In these experiments fillets from several sites were evaluated for the texture studies and also color measurements were taken for all samples. Analysis of the fillet color data is under way. Progress was made on Objective 2, enhancing the utilization of byproducts from aquaculture product processing. This is an important project as it can increase the value of “waste” materials from catfish left after processing. A starting point for byproduct research is to determine the composition of the byproducts, with one variable being differences in the composition of the byproduct components from male and female fish. Catfish byproduct samples have been collected by ARS researchers in New Orleans, Louisiana, from catfish where the gender was determined before processing. The composition of the byproducts from males and females are being determined. This work will be made available to the processor and researchers to find new uses and add value to these byproducts. Additional progress made on Objective 2 to develop value-added products from catfish byproduct. ARS researchers in New Orleans, Louisiana, in collaboration with researchers from Louisiana State University, Baton Rouge, Louisiana, developed a process for producing catfish skin hydrolysates. The quality characterization of the catfish skin hydrolysates have been determined and currently the shelf life of the powdered hydrolysate is being completed. Potential uses of the hydrolysate include as an antioxidant in food systems, and as a coating to increase the shelf life of foods. Another project in the final stages of completion involves developing powdered bone from catfish frames. Powered bone products from the catfish frames has potential use as a food or feed supplements.

Accomplishments
1. Method development for measurement of catfish fillet texture. Catfish texture is important to consumers, especially if the texture does not meet consumer expectations for uniform product hardness and mouthfeel characteristics. Therefore, texture of farm-raised catfish has received much interest and ARS researchers at the Southern Regional Research Center in New Orleans, Louisiana, have developed a method for quickly evaluating fillet texture. Two treatments, fresh frozen and individually quick frozen with added phosphate, were evaluated using both sensory evaluation of texture and mechanical methods of texture determination. The two sets of catfish samples (fresh frozen and individually quick frozen) were compared and found to have slightly different texture qualities. A mechanical texture measurement method was developed by ARS researchers to predict the sensory texture measurements. This will lead to methods for catfish processors to quickly and conveniently monitor texture quality and for evaluation of other factors altering fillet texture characteristics for a better value for catfish.

Review Publications
Bechtel, P.J., Bland, J.M., Woods, K., Lea, J.M., Brashear, S.S., Boue, S.M., Daigle, K.W., Bett Garber, K.L. 2018. Effect of par frying on composition and texture of breaded and battered catfish. Foods. 7:46. https://doi:10.3390/foods7040046.
Bonilla, F., Chouljenko, A., Reyes, V., Bechtel, P.J., King, J.M., Sathivel, S. 2018. Impact of chitosan application technique on refrigerated catfish fillet quality. Journal of Food Science and Technology. 90:277-282.
Bland, J.M., Bett Garber, K.L., Li, C.H., Brashear, S.S., Lea, J.M., Bechtel, P.J. 2018. Comparison of sensory and instrumental methods for the analysis of texture of cooked individually quick frozen and fresh-frozen catfish fillets. Food Science and Nutrition. 1692-1705. https://doi.10.1002/fsn3.737.
Tan, Y., Haoran, G., Chang, S.K., Bechtel, P.J., Mahmoud, B.S. 2018. Comparative studies on the yield and characteristics of myofibrillar proteins from catfish heads and frames extracted by two methods for making surimi-like protein gel products. Food Chemistry. https://doi.org/10.1016/j.foodchem.2018.07.201.