1a. Objectives (from AD-416):
The overall goal of this research project is to increase consumer demand for catfish products and profitability of the catfish industry by developing new and improved products, improving product quality and increasing utilization of catfish by-products. The three project objectives follow: 1) Develop methods to improve quality and uniformity of catfish fillets and nuggets; 2) Development of new and value added catfish products that will meet consumer demand; and 3) Enhance the utilization of by-products from aquaculture product processing.
1b. Approach (from AD-416):
This project will work closely with the commercial processing industry to improve the perception of catfish quality, to develop new catfish products, and evaluate the potential new use for catfish by-products. Approaches will include characterizing the color variation in catfish fillets, and investigating causes of color variation. Machine vision software will be developed to aid in the mechanically separation of catfish fillets based on color. New catfish products to be developed will include a batter and breaded catfish fillet that can be oven cooked, and meets the requirements for inclusion into school lunch programs. New coated and marinated catfish fillet products will be developed for niche markets. The initial approach for the by-product studies will be to determine the composition of both channel and hybrid catfish by-product components as the first step in developing novel value added products from underutilized catfish waste.
3. Progress Report:
This new project was approved by NP 106 (Aquaculture) in late November 2012. New methodologies for the extraction, chromatography, and identification of catfish carotenoids have been developed using accelerated solvent extraction, normal-phase silica chromatography, and atmospheric photo ionization (APPI) mass spectrometry. Carotenoids levels in hybrid catfish have been compared to channel catfish. Colorimetric measurements of channel and hybrid catfish patties have been evaluated and used to distinguish between patties cooked by different methods including frying, baking, and cooking under pressure. Analysis of the patties for composition and color and carotenoid content has been completed and of other nutrients are being analyzed. Analysis of catfish fillets has been initiated to determine color level using machine vision. Preliminary C++ programming has been obtained to devise a protocol to categorize catfish fillets by machine vision. The modified protocol will be used with a machine vision system to sort fillets based on fillet color. Studies are under way to develop new batter and breaded catfish fillet strips, that are not par fried, can be oven cooked, and meet requirements for inclusion into school lunch programs. Initial studies included evaluation of corn, wheat and rice flour batters. Analysis is being completed for proximate composition, texture profile using a trained sensory panel and mechanical texture analysis. Using the best batter from the first experiment, a second set of studies will evaluate precooked wheat and corn breading to obtain a crisp textured product. Analysis of the final product will include product composition and nutrient content per 100g of product (cooked and uncooked). An additional study being conducted with an Auburn University faculty member will evaluate the texture properties of cooked fillets from pond and raceway reared channel and hybrid catfish. Initial byproducts studies (Objective 3) have focused on comparisons of channel and hybrid catfish byproducts obtained from commercial catfish processors. Triplicate samples of each byproduct were collected from both channel and hybrid catfish and transported to the Southern Regional Research Laboratory in New Orleans, LA, for analysis. Samples were the common commercially available byproducts including catfish viscera, heads, frames and skins. Samples were ground and portions freeze dried and then proximate analysis of the samples was determined. Other determinations being completed on the samples include amino acid analysis, determination of fatty acid profiles, and evaluation of mineral content. This initial byproduct study will be used to determine the composition of both channel and hybrid catfish byproducts, which is the first step in developing novel value added products from underutilized catfish waste.
1. Cartenoid content in channel and hybrid catfish. One problem for the catfish industry has been variation of fillet color, and some fillets have a yellow color thought to be caused by carotenoids in their diet. The objective of this study was to compare the most abundant carotenoids from channel and hybrid catfish. United States Department of Agriculture, Agriculture Research Service (USDA/ARS) scientists from the Southern Regional Research Center (SRRC) in New Orleans, LA, collected fresh channel and hybrid catfish fillet samples from a commercial processor in Mississippi. Samples were freeze dried and then extracted with acetone; and carotenoids were identified using liquid chromotography/mass spectrometry (LC/MS) (Silica column, APPI). Two major carotenoids, lutein and zeaxanthin, were identified in both the channel and hybrid fillets, and the average content in channel catfish was higher that in the hybrid fillets. This study identifies the major carotenoids in hybrid catfish, and will support efforts to standardize the color of catfish fillets.
Otoni, C.G., Avena Bustillos, R.D., Chiou, B., Bilbao-Sainz, C., Bechtel, P.J., Mchugh, T.H. 2012. Ultraviolet-B radiation induced crosslinking improves physical properties of cold- and warm-water fish gelatin gels and films. Journal of Food Science. DOI:10.1111/j1750-3841.2012.02839.x.