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.
Characteristics of selective fluoride adsorption by biocarbon-Mg/Al layered double hydroxides composites from protein solutions: kinetics and equilibrium isotherms study.
In the study, two novel applied biocarbon-Mg/Al layered double hydroxides composites (CPLDH and CPLDH-Ca) were successfully prepared and characterized by TEM, ICP-AES, XFS, EDS, FTIR, XRD, BET and pHpzc. The fluoride removal efficiency (RF) and protein recovery ratio (RP) of the adsorbents were studied in protein systems of lysozyme (LSZ) and bovine serum albumin (BSA). The results showed that the CPLDH-Ca presented remarkable performance for selective fluoride removal from protein solution. It reached the maximum RF of 92.1% and 94.8% at the CPLDH-Ca dose of 2.0g/L in LSZ and BSA system, respectively. The RP in both systems of LSZ and BSA were more than 90%. Additionally, the RP of CPLDH-Ca increased with the increase of ionic strengths, and it almost can be 100% with more than 93% RF. Fluoride adsorption by the CPLDH-Ca with different initial fluoride concentrations was found to obey the mixed surface reaction and diffusion controlled adsorption kinetic model, and the overall reaction rate is probably controlled by intra-particle diffusion, boundary layer diffusion and reaction process. The adsorption isotherms of fluoride in BSA system fit the Langmuir-Freundlich model well. The BSA has synergistic effect on fluoride adsorption and the degree increased with the increase of the initial BSA concentration.
Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System
An automated procedure for photometric titration of red wine and associated instrumentation is described. The procedure was based on the flow-batch approach implemented employing multicommutation. The photometric detection was carried out using a homemade LED-based photometer. The mixing device, LED, and photodetector were attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which were controlled by a microcomputer through an electronic interface card. The software, written in Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titration procedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC reference method, no significant difference was observed at the 95% confidence level. A relative standard deviation of ca  2% (n=9 ) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.