Location: Food Processing and Sensory Quality Research
2015 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
The new five year Action Plan for this NP 106 project was approved and initiated on May 19, 2015 and this annual report covers the period to September 30, 2015. This project was preceded by NP 106 project, 6435-43440-047-00D, which was completed on 05/18/2015. This project is related to NP 306 Project No: 6054-44000-077-00D, titled “Postharvest Sensory, Processing and Packaging of Catfish” and annual reports share accomplishments #1 and #2.
Catfish processing plant flavor checkers were visited to learn about the catfish flavor checking process and variations in the process. A survey was then developed and information was gathered from most of the Mississippi, Alabama, and Louisiana catfish processing plants. An initial catfish processors flavor checking workshop was presented in 2015 with a large percentage of the commercial processors represented. From this workshop, needs of catfish flavor checkers were identified and work was initiated on the nomenclature of catfish flavor attributes and comparisons of methods used by the flavor checkers.
The yellow off-color problem associated with some catfish fillets is caused by carotenoids that are deposited in the fish fat. A study was completed to improve the method used to identify the carotenoids responsible for the yellow color found in some catfish fillets. Results indicated that the new method was superior to the normal method used for carotenoid identification. A study was initiated to evaluate the carotinoid content in four different areas of catfish fillets and correlate the carotenoid content with the fat content. Samples have been collected for a second study in which the fat content of the fillets is higher and will be more indicative of the fat content found in commercially available catfish.
The major byproducts from farmed catfish including heads, viscera, frames and skin were collected along with fillet and the yield of the individual byproducts as a percent of fish weight is being determined, and in addition the major off flavor compounds in the individual byproducts and fillets are being determined in the byproducts and fillets. Two studies are underway to add value to catfish byproducts. The first study is to evaluate the mineral composition of the cleaned bone from channel and hybrid frames for potential uses as food and feed ingredients and supplements. The second study utilizes gelatin extracted from catfish skins as a coating agent to improve the quality of frozen catfish fillets and shrimp during storage.
Accomplishments
1. Determining the number of fish needed to be analyzed in order to detect off-flavor catfish in ponds. Scientists at the Agricultural Research Service, New Orleans, Louisiana determined the number of fish that would need to be analyzed in order to detect off-flavor catfish in mixed ponds. Data was used to model the number of fish required to detect off-flavor in mixed populations containing both on and off flavor fish. A sample of 40 fish was required to detect off-flavor when the population was nearly all on-flavor (97%) and <11 fish when populations contain >20% off-flavor fish. A sample size of six fish in a mixed population was effective in identifying off-flavor occurrence in 60% of ponds having off-flavor present. Sampling more fish fewer times can more accurately identify ponds containing mixed flavor fish populations than the current sampling procedure.
2. Catfish flavor checkers workshop. Scientists at the Agricultural Research Service, New Orleans, Louisiana held a catfish flavor checkers work shop on March 19, 2015 in Indianola, Mississippi. Prior to the workshop a survey of the catfish processing plant flavor checkers to learn about differences in the flavor checking processes. A survey was developed and information was gathered from most of the Mississippi, Alabama, and Louisiana processing plants. At this workshop, the results of the survey were discussed; and participants were presented samples to determine their perception thresholds for perceiving the most common catfish off-flavors, geosmin and methylisoborneol. This workshop provided the starting point for work on the nomenclature for catfish flavor attributes.
