Location: Food Processing and Sensory Quality Research
2019 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 sub objectives of Objective 1, which falls under National Program 106, Aquaculture, Component 5, Product Quality and New Products. Objective 2 milestones were not met because of reduced manpower, due to retirement of team member that required the objective to be discontinued. Significant progress was made by ARS researchers in New Orleans, Louisiana, on the development of a new method of measuring the texture of raw and cooked catfish fillets. The sensory qualities of catfish fillets is of primary importance to the processor and consumer. Textural quality of the cooked fillet can be equal to taste for subsequent rejection or acceptance by the consumer, but texture of raw fillets is also of great concern at the processing facility where differences can cause difficulties with the mechanical filleting requirements. Texture problems with catfish fillets include soft or mushy texture and occasional fillets that are too firm. In addition, an unknown in catfish texture was a possible difference between males and females. This gender difference and differences between raw and cooked fillets were investigated to complement last year’s studies of differences between fresh, frozen, and IQF (containing polyphosphate) processed fillets. Results demonstrated that the gender did not directly affect fillet texture, but differences were found between raw and cooked fillets that varied, depending on the gender, where males caused greater textural differences than females.
Accomplishments
1. Method development for measurement of catfish fillet texture. The sensory qualities of catfish fillets is of primary importance to the processor and consumer. Textural quality can be equal to taste for subsequent rejection or acceptance by the consumer, and may also create processing difficulties with variable filleting requirements. Therefore, texture of farm-raised catfish has received much interest and ARS researchers in New Orleans, Louisiana, have developed a method for quickly evaluating fillet texture. Differences between male and female catfish of raw and cooked fillets were evaluated using instrumental methods of texture determination. No differences were found between genders. However, gender differences were seen in comparisons of raw and cooked catfish. Two texture attributes were significantly different between raw and cooked for female catfish, but for male catfish, four attributes were significantly different. Since the gender of catfish fillets is not normally known at the processor or the consumer, knowledge of lack of differences between them should have a positive impact on overall product acceptance. Correlations between raw and cooked fillet texture may give guidance to further research of production methods.
2. Method development for spatial analysis of fat in catfish fillets. The compounds responsible for catfish off-flavor and yellow off-color are very soluble in fat, so the (spatial distribution map) of fat across the catfish fillet is important in understanding and treatment of the flavor and color quality problems. Past methods required large amounts of fillet that prevented a defined spatial mapping. Methods were also limited by the time for analysis. A new method that uses time-domain nuclear magnetic resonance (TD-NMR) was developed by ARS researchers in New Orleans, Louisiana, to overcome these limitations. The TD-NMR method allowed a smaller sample size to be analyzed, which provided a more focused map of the fat content within the fillet. Also, the analysis time was reduced from days in the previous method to seconds for each point in the map using the TD-NMR method. In addition, the new method was non-destructive, so samples could be utilized for other studies, such as color and possibly off-flavor analysis. The TD-NMR method can benefit researchers and processors with a rapid analysis (seconds) of fat content of the fillet. The spatial analysis of fat and its correlation with off-flavor or color can benefit flavor checkers and processors in deciding which fillet region is best for determining quality problems or how to more efficiently trim the fillet.
