Pilot plant scale production of protein from catfish treated by acid solubilization/isoelectric precipitation.

Catfish fillets were minced and acid (pH 3.0) solubilized in dilute conditions (1:9). Insolubles were removed by centrifugal force (3000 xg) and the soluble protein was recovered by isoelectric precipitation (pI approximately 5.4). Moisture and NaCl of the batters were equilibrated to 78% and 2%, respectively. Samples were stuffed into casings, cooked, and chilled. Proximate composition, color, cook yield, water holding ability (WHA), and texture profile analysis (TPA) were determined. Treatment of catfish protein by the solubilization process removed 74% of the fat. In addition, gels from treated protein were less red (-1.61 compared with -1.06) and yellow (6.58 compared with 7.09). There was no difference in whiteness (72.0 compared with 71.8) of gels or in percent cook yield (94.6% compared with 95.0%) between treated protein and the control, respectively. The WHA of gels made from control protein was 0.73 g/g protein higher than treated. The texture analysis indicated that treated proteins had significantly higher hardness (1193 g compared with 1046 g), springiness (0.919 compared with 0.897), chewiness (0.701 compared with 0.584), and cohesiveness (0.637 mJ compared with 0.619 mJ). The resilience was equivalent for both treated and control gels. The results indicated the protein solubilization process produced a low fat protein product with good gel strength properties.