Development of smoked and gelatin-based products from catfish

Abstract

Catfish is the most important aquaculture species in the southern United States. A major part of the catfish production is processed and sold in raw (fresh or frozen) form. There is a lack of catfish product forms in the market which can potentially add value to the existing products and create more job opportunities. The potential of hot-smoked catfish fillets was studied as a value-added and ready-to-eat (RTE) catfish product. Textural properties play an important role in the quality control and acceptability of both raw and processed products. Consequently, textural properties of raw and smoked catfish fillets were measured by “finger” or “tooth” methods together with a novel sampling technique. The “finger” method was proven to be a better method for texture measurement on catfish fillets. The sampling technique was rapid and applicable to most irregular fillet shapes, including catfish and other fish species. Brining of fish is one of the critical control points (CCPs) in the hot-smoked fish products. Brining behavior of fresh catfish fillets was studied. Salt content of smoked catfish was determined by both the traditional titration method and novel near infrared spectroscopy (NIR) methods. Nonlinear and multiple linear regression (MLR) models were developed to predict the catfish brining behavior. In order to evaluate products’ shelf-life, hot-smoked catfish fillets were individually packaged in film with different oxygen transmission rates (OTR, 0, 4,000, and 10,000 cm3/m2/24h/atm at 20 °C and 0%RH) and stored at either 4 or 25 °C. Shelf-life of 53-, 35-, and 33-day was observed for samples stored at 4 °C and packaged with 0, 4,000, and 10,000 OTR films, respectively. Shelf-life of 3 to 5-day was observed for samples stored at 25 °C. The utilization of catfish processing by-product was also studied. Gelatin was produced from catfish skin by thermal extraction. Gelatin film was prepared with different levels of triacetin in the film forming solutions. Structures of the films were examined using a transmission X-ray microscope (TXM). Addition of triacetin caused decreased tensile strength (TS) and increased percent elongation (E%), water solubility, UV and visible light barrier properties of the film.