Production, Process Design and Quality Characterization of Catfish Visceral Oil.

Between 45--55% of viscera, head, skin, intestine and slurries are generally generated as byproducts or waste from catfish filleting process. Our preliminary study showed that the crude fat content of the whole catfish viscera was 30--35% (wet basis) and the total o-3 fatty acids of oils recovered from the whole and/or portioned viscera ranged from 4.3--20.9 mg/g (dry basis). Catfish viscera may serve as an excellent source of health-promoting oil. Yield of purified (deodorized) catfish visceral oil was 65.7% and contained considerable amounts of DHA (1.21 mg/g of oil) and omega-3 fatty acid (4.6 mg/g of oil). A rapid microwave-assisted method for fatty acid analysis was developed. The microwave heating power (%) and time (sec) required for maximal fatty acid recovery were determined. Heating at 100% power for 80 sec yielded the highest recovery of DHA (C22:6 o-3) and arachidonic acid (C20:4 o-3). The adsorption of free fatty acid of crude catfish oil was performed with chitosan, activated carbon and/or activated earth as adsorbents. Batch adsorbent experiments were carried out to assess equilibrium parameters. Chitosan was the most effective adsorbent to adsorb free fatty acids. The fixed-bed adsorption study showed that the highest percent of bed length was used when chitosan was used as an adsorbent. Melting points, specific heat capacity, enthalpy, and heat resistance were studied using DSC (Differential Scanning Calorimeter) and TGA (Thermogravimetric analysis). Melting points, enthalpy, and specific heat capacity varied greatly among the catfish oils from different processing stages due to differences in impurities. Catfish visceral oils from different processing steps showed different rates of weight loss with increased temperature. Suitability of Newtonian, Herschel-Bulkley, Bingham plastic, and Casson models to characterize the flow behavior of catfish oils form different processing steps was investigated. The Casson equation sufficiently described the flow behavior of catfish oils. The research findings from this study will benefit the whole catfish industries and will set a good model for fish oil recovery from other fish species as well

Rice bran stabilization and rice bran oil extraction using ohmic heating

This study investigated pectin-based capsules as delivery systems for purple rice bran anthocyanin extract (AE) during exposure to simulated gastrointestinal conditions. Four different capsules loaded with AE were prepared by ionotropic gelation/extrusion, including (1) pectin capsules (PE), (2) pectin capsules coated with zein (PE/ZE), (3) pectin-whey protein isolate complex capsules (PE + WP), and (4) pectin-whey protein isolate complex capsules coated with zein (PE + WP/ZE). CaCl in an ethanol solution with or without zein was used as a crosslinking solution. Swelling and release characteristics of all capsules under simulated gastric fluid at pH 1.2 (SGF) and simulated intestinal fluid at pH 6.8 (SIF) for 120 and 180 min, respectively, were examined. PE + WP, PE + WP/ZE, and PE/ZE capsules had higher encapsulation efficiency than PE capsules. After incubation, PE + WP/ZE and PE capsules had the lowest swelling ratio in SGF and SIF, respectively. PE + WP/ZE capsules had the lowest AE release in SGF, while PE capsules had the highest. Both PE + WP and PE + WP/ZE capsules had significantly lower AE release in SIF than PE and PE/ZE capsules. The study demonstrated that PE + WP and PE + WP/ZE capsules have potential to function as a slow release delivery system for AE

Development of pelleted feed containing probiotic GG and Jerusalem artichoke for Nile Tilapia and its biocompatibility studies

Growth performance and immune systems of tilapias could be improved by GG (LGG) and Jerusalem artichoke. This research aimed to determine the effects of Jerusalem artichoke on LGG viability after drying and pelleting and their subsequent exposure to simulated gastrointestinal conditions. Fresh LGG cells were added into wall material solutions, including alginate (AL), alginate + milk powder (AM), and alginate + milk powder + Jerusalem artichoke at different concentrations (AMJ). The solutions were then spray dried to obtain LGG powders. The powder with the highest cell number was then selected to mix with tilapia feed mash and pelleted using a nonthermal feed extruder to obtain pelleted feed containing LGG and Jerusalem artichoke. The LGG viability spray dried powders and pelleted feed were analyzed for their cell counts after drying and after exposure to simulated gastrointestinal conditions. The result showed that the number of viable cells in AMJ was significantly higher than AM and AL after drying. The number of viable cells under both simulated gastric and bile salt fluids was improved with the increasing of Jerusalem artichoke concentrations. The number of viable cells after pelleting process could be maintained. LGG in the pelleted feed could also survive under the simulated gastric and bile salt conditions. The study indicates that JA enhanced LGG viability after drying and exposure to simulated gastrointestinal conditions. The pelleted feed containing LGG and Jerusalem artichoke could be applied in tilapia farming, providing convenience to the farmers, and valuable effects to the fish

Functional properties of protein fractions of channel catfish (Ictalurus punctatus) and their effects in an emulsion system

This study demonstrated the feasibility of producing soluble protein (CFSP) and insoluble protein (CFISP) fractions from catfish muscle protein. CFSP and CFISP contained 60.6% and 73.8% protein and 8.6% and 20.3% fat, respectively. Both CFSP and CFISP contained essential amino acids. Differences were observed between physicochemical properties of the 2 protein fractions, including nitrogen solubility, emulsion stability, and fat adsorption capacity. The flow and viscoelastic properties of the emulsions prepared with CFSP and CFISP were investigated using a rheometer. The power law model and the Casson model were used to determine the flow behavior index (n), consistency index (K), and yield stress. Emulsion containing CFSP (ECFSP) had a higher K value than emulsion containing CFISP (ECFISP). Both ECFSP and ECFISP emulsions exhibited pseudoplastic behavior and viscoelastic characteristics. The G\u27 (an elastic or storage modulus) and G″ (a viscous or loss modulus) values for ECFSP were higher than ECFISP. Catfish muscle tissue can be easily separated into soluble and insoluble protein powders that have desirable functional properties

Delivery of alpha-tocopherol through soluble dietary fibre-based nanofibres for improving the life span of Caenorhabditis elegans

The effect of alpha-tocopherol (α-TOC) delivered by soluble dietary fibre-based nanofibres (α-TOC-SDNF) on the life span of nematode Caenorhabditis elegans N2 (wild type) and TK22 (mev-1 mutants) with and without heat shock was investigated. Without heat shock, the wild-type and mev-1 mutants maintained in the 100 µg/mL of α-TOC-SDNF had longer life spans than their respective blank control groups. With heat shock, the wild-type N2 in the 200 µg/mL of α-TOC-SDNF had a survival rate of 5% at day 49, while no nematodes survived in the blank control group. An increased pharyngeal pumping rate was observed in the α-TOC-SDNF treated mev-1 mutants worms compared to the blank control group. Encapsulating α-TOC in SDNF yielded protective effects and the life span and pumping rate of C. elegans was increased with α-TOC delivered by SDNF

Effect of bambara groundnut supplementation on the physicochemical properties of rice flour and crackers

This study evaluated the effect of bambara groundnut supplementation on the physicochemical properties of local rice flour and baked crackers. Bulk and true density, porosity, water absorption index, oil absorption capacity, pasting properties by RVA, morphological appearance by SEM, color by calorimetry, and textural properties by TA.XT2 analysis of wheat and two formulations of rice-legume flours and crackers were studied. Moisture (10.94%) and carbohydrate (77.42%) levels were significantly greater in wheat flour than the rice-legume flours, while the reverse was true for fat and ash. Also rice-legume flours had significantly greater water and oil absorption capacity and lower water solubility compared to wheat flour. Compared to wheat crackers, rice-legume crackers had greater fat and ash, 20.51 and 3.57%, respectively, while moisture was significantly lower in the rice-legume crackers by 41 to 58%. Rice legume crackers were significantly harder and had significantly increased spread ratio. The results obtained from the development of locally grown rice and underutilized legume bambara groundnut showed great promise in physicochemical and functional properties and may be a good replacement for wheat flour to serve as a gluten-free product