Quality deterioration of smoked catfish is caused by lipid oxidation and microbial spoilage. Smoked catfish can be cross-contaminated during processing and may harbor several pathogens, e.g., Listeria monocytogenes, and Salmonella spp. Lipid oxidation causes unpleasant flavor, thus making smoked fish unacceptable. Hydroperoxides and free radicals, formed during oxidation, may directly react with fish tissues to promote complex reactions. Through such complex reactions, physicochemical properties of smoked catfish may be adversely affected. A combination of smoking and treatments with antimicrobial agents and antioxidants would retard microbial spoilage, extend shelf life, and enhance safety of smoked catfish. The objective of this study was to assess microbial and physicochemical quality of smoked catfish (Ictalurus furcatus) treated with antimicrobial agents and antioxidants during 6-week storage at room temperature. Raw catfish steaks were subjected to the following treatments for 30 minutes prior to smoking: 25% NaCl and 1% ascorbic acid; 3% sodium lactate; 3% sodium lactate and 5% rosemary extract; and/ or 5% sorbic acid. The non-treated catfish served as control. Smoked catfish samples were drawn after 0, 2, 4, and 6 weeks for microbial, pH, water activity, proximate, color, thiobarbituric acid reactive substances (TBARS), and peroxide value (PV) analysis. All treated smoked catfish had a water activity (aw) less than 0.85 compared with 0.94 for the control. Total plate count (TPC) for all dried samples was 1.2- 2.2 log CFU/g at day zero and increased to 1.48-3.0 log CFU/g after 4-week storage. The control was moldy after 6-week storage. No mold was observed on samples treated with sodium lactate, or sorbic acid even after 4-week storage. No Salmonella and Listeria monocytogenes were isolated from any smoked samples. Samples treated with 3% sodium lactate had the lowest microbial loads and were shelf-stable up to 6 weeks without refrigeration. The sample treated with rosemary extract was more stable to oxidation than all other treatments. Protein content of smoked sample ranged from 54 to 87%, 2.82 to 5.80% for ash, 13.11 to 22% for fat, and 11 to 22% for moisture. No significant change in color of smoked catfish was observed during storage. Sodium lactate treatment was most efficient in controlling microbial quality and extending shelf life of smoked catfish.

The present work aimed at recovering, purifying, and testing rice cystatin or oryzacystatin I (OCI) bioavailability, to provide scientific evidence that rice cystatin can be used as a functional food ingredient. OCI was extracted from rice bran using 25 mM sodium phosphate buffer containing 0.15 M NaCl at pH 7.0. The resulting homogenate was heat treated, cooled and precipitated with ammonium sulfate. The recovered protein was dialyzed against 50 mM sodium acetate buffer pH 4.8 and sequentially purified by cation exchange, size exclusion, and anion exchange chromatography. Nine hundred and seventy micrograms of protein were obtained from 1 kg of rice bran. SDS-PAGE provided one pure band. MALDI-MS identified the protein at 11,538 Da. Overall there was a 14-fold increase in specific activity throughout the purification process. OCI was hydrolyzed with chymotrypsin in 20 mM sodium phosphate buffer pH 7.4 for 2.5 hours at 37°C at an enzyme to protein ratio of 1:100. The resulting chymotryptic peptides yielded a higher inhibitory activity compared to unhydrolyzed OCI (145% increase). The permeability of OCI and OCI chymotryptic peptides across Caco-2 cells was evaluated for 3 hours at 37°C. Unhydrolyzed OCI did not cross the cell monolayer. OCI chymotryptic peptides were uptaken by the Caco-2 cells, as they were not detected in the apical side of the cells either by MALDI MS or papain inhibitory activity assay. After three-hour incubation, only one peptide with a molecular weight of 5.8 kDa was detected in the basolateral side of the cells. The peptide that crossed the basolateral membrane had no inhibitory activity versus papain. The significance of these findings and future research direction will be discussed.

An efficient procedure was developed and used to extract and purify isoflavones from defatted soy flour. The purity of the final product reached 94%. The antioxidant activities of soybean isoflavones (genistein and daidzein purchased from Sigma Chemical Co, and a mixture of isoflavone glycosides extracted from defatted soy flour) were investigated by a cholesterol oxidation model accelerated by 2,2-azobis(2-methylpropionamidine) dihydrochloride (AAPH). All components exhibited very high antioxidant activities in the inhibition of cholesterol oxidation. Genistein had higher inhibition to the formation of 5,6beta-epoxycholesterol (5,6b-EP) and 7-ketocholesterol (7-keto), while no significant difference was found between the antioxidant activities of daidzein and genistein against cholesterol oxidation to 7beta-hydroperoxycholesterol (7b-OOH) and 5,6alpha-epoxycholesterol (5,6a-EP). The glycosides mixture had characteristics similar to genistein and daidzein in preventing cholesterol oxidation, but the glycosides mixture was found to have lower antioxidant activities compared to aglycones. The biological activities of genistein and daidzein to affect cellular response in SVEC4-10 mouse endothelial cells to t-butyl hydroperoxide-induced oxidative stress were also evaluated. Genistein had higher cytotoxicity than daidzein to SVEC4-10 cells and none exerted discernable antioxidant activities in this cell culture model. The antioxidant activities of soybean isoflavones may contribute to their potential role in reducing the formation of certain types of cancers, so daidzein might be a more appropriate cancer preventive neutraceutical because of its lower cytotoxicity. In view of the high cytotoxicity, this cell culture model might not be suitable for the study of antioxidant activity of soybean isoflavones. Some modifications or another cell culture model is needed in order to further this study of antioxidant activity. Defatted soy flour is a by-product of oil extraction, so the antioxidant activities of soybean isoflavones could improve the utilization of the by-product and benefit the soy industry.

Health benefits from consuming rice bran oil (RBO) have been extensively studied in humans. RBO has been shown to decrease cholesterol absorption by inhibiting the oxidation of the LDL-cholesterol. Gamma-Oryzanol is one of the RBO components that possess antioxidative properties; it is a polyphenolic compound resembling tocopherol (vitamin E), which is another component of RBO. There are evidences that oryzanol has potential applications for enhancing shelf-life of foods containing fats processed at a high temperature, decreasing the total cholesterol, LDL-cholesterol and triglyceride levels in plasma lipids, and healing ulcers. In order to take advantage of the health benefits of oryzanol, food products fortified with oryzanol should be developed and characterized. Cheddar cheese containing Gamma-Oryzanol was developed, and the effects of oryzanol on cheese quality during ripening process were studied. Cheese was stored for 5 months and drawn every month for quality evaluation of color, texture, microbial growth, aroma development, bacterial identification by polymerase chain reaction, oryzanol retention, moisture content and free fatty acid profile. The consumer acceptance was evaluated after 5 months of maturation. The results indicated that by adding Gamma-Oryzanol to cheddar cheese changes occurred in the quality, but, they were not significant when stored for up to 4 months, and the Gamma-Oryzanol was well retained. Consumers were able to differentiate the cheddar cheese containing Gamma-Oryzanol from the control containing no Gamma-Oryzanol. Overall appearance, texture, taste and hardness were the most discriminatory sensory attributes. There was a significant positive increase 0.13 to 0.30 times higher in the purchase intent of cheddar cheese containing Gamma-Oryzanol after consumers had been informed about the health benefits of oryzanol. Overall liking was the attribute critical to purchase intent and the most important attribute that changed the acceptability of the cheese. Consumers preferred the cheese with Gamma-Oryzanol less than the control but were willing to buy it and compromise the overall liking of cheese merely to get the health benefits of the product. Further studies need to be done to determine the direct effects of cheddar cheese containing Gamma-Oryzanol in human health, and to optimize the homogenization and fortification of Gamma-Oryzanol when incorporated in cheese products.

Rice bran oil (RBO) has been considered healthy cooking oil with potent effects to reduce the risks of atherosclerosis and coronary heart disease. The relatively high level of unsaponifiable components contributes to the healthy benefits of RBO. This study investigated the possibility that the cholesterol-lowering effects of oryzanol are through increased fecal steroid excretion. The objective was to compare fecal cholesterol and bile acid excretion as well as bioavailability among different forms of oryzanol. The correlation between bioactivity and bioavailability of oryzanol was investigated as well. Forty-seven female breeder rats were used as animal models. Oryzanol was added to an AIN-93 M maintenance diet at 2.8g/kg as the treatments. Treatments were either oryzanol in RBO, dissolved oil form of oryzanol in corn oil, or crystalline form of oryzanol added directly to the diet. Control was corn oil. Fecal samples were collected at week 6 and 10. Fecal cholesterol, oryzanol, and bile acids were analyzed with GC-FID. Results showed no significant differences between the two collection periods (P>0.05). Oryzanol in RBO produced the greatest fecal cholesterol excretion among the diet groups (P<0.05). Both fecal cholesterol and total bile acid excretion were significantly higher in rats fed RBO oryzanol than the average of the other two treatment groups (P<0.001). It may indicate that the hypocholesterolemic activity of RBO with oryzanol was more effective than oryzanol in corn oil, through synergistic effects of the components in the unsaponifiable contents. The possible mechanism for RBO and oryzanol to lower cholesterol levels appeared to be through inhibiting cholesterol absorption and bile acid reabsorption to enhance fecal cholesterol and bile acid excretion. The effect of treatment compared to control was greater for bile acid excretion than for cholesterol excretion, which may suggest the primary mechanism of the hypocholesterolemic effect of oryzanol may be through the interference of bile acid reabsorption in the enterohepatic circulation. The correlation among different forms of oryzanol to the bioactivity was unclear, although the results showed fecal recovery of oryzanol was positively related to fecal steroid excretion. It might indicate the absorbability of oryzanol was negatively related to fecal steroid excretion.

Rice is an important commodity in Louisiana and throughout the world. During the milling process, about 15% of rice kernels become broken. Louisiana produced approximately 2,011,000 hundred weights of broken rice kernels in 2002. Converting broken rice into rice-based products adds dollars back to broken rice. The market potential for rice in processed foods is huge. In the refrigerated and frozen baked foods category, it is approximately $14.3 billion; while in the baked snack foods and wholesale bakery foods category, it is approximately $31.4 billion. Approximately 1-2% of the United States population suffers from Celiac Spruce Disease, which is a result of the malabsorption of certain proteins in the diet, specifically gluten. Gluten can be found in almost all cereal grains, including wheat, rye, oat, and barley. Rice, however, does not contain gluten, which makes it an ideal food for individuals with this disease. A butter cake product was formulated using predominantly rice flour. Consumer studies were performed to determine 1) attributes critical to product acceptance and purchase decision, 2) the optimal formulation of the butter cake product, and 3) whether or not consumers were able to correctly differentiate between butter cake samples made either from wheat, rice, or a mixture (50:50) of wheat and rice. Logistic regression analyses identified overall liking, taste and texture as attributes critical to overall acceptance and purchase decision. Predictive discriminant analysis also identified if overall liking, taste, moistness, and texture contribute significantly to overall differences among the three butter cake formulations. Superimposition of the optimal response surface areas of overall liking, taste and texture revealed that formulations containing 50-95% wheat, 0-50% rice and 0-40% pre-gelatinized rice flours would yield a product with acceptability scores greater than 6.0. Consumers were able to correctly discriminate between the different formulations of butter cake (100% rice flour, 50/50 wheat/rice flours) when compared to the labeled control formulation containing 100% wheat. Consumers would be willing to compromise certain attributes in order to gain a potential health benefit from consuming this product, especially if they are not able to consume wheat products.

Chitosan is made from chitin by a chemical process involving demineralization (DM), deproteinization (DP), decolorization (DC), and deacetylation (DA). Very little work has been done to demonstrate the effects of altering or excluding any of the processing steps on chitosan characteristics. The present study was undertaken to evaluate the effects of process modification during chitosan production on the physiochemical and functional properties of crawfish chitosans. Five experimental chitosan samples (DCMPA, DMCPA, DMPCA, DMPAC, DAMPC) prepared with modified processing protocols and the control (DPMCA - traditional chitosan production process) were evaluated and compared with the two commercial crab chitosans. All samples were subjected to physicochemical (moisture, nitrogen, and ash contents, degree of deacetylation, molecular weight, viscosity, solubility, bulk density, and color) and functional (water binding capacity, fat binding capacity, emulsion capacity, and emulsion viscosity) characteristic analysis. Three experimental replicates were performed with a duplicate analysis of each sample. Results indicated that process modification of crawfish chitosan production yielded some differences on each characteristic compared with the control and commercial chitosans. For instance, changing the sequence of DC for the production of crawfish chitosan affected its properties. DCMPA and DMCPA resulted in an increase in molecular weight and ash, respectively. In contrast, DMPCA led to lower viscosity. The most notable change observed with the DMPAC chitosan was a light brown degraded colored chitosan that exhibited properties of a weak polyelectrolyte. When chitosan process started with DA, a very poor of yield were obtained. When DM and DP were reversed during production, the results showed some difference, e.g., the lower viscosity, higher fat binding capacity, and higher emulsion viscosity of DMPCA over DPMCA. This study demonstrated that process modification of crawfish production affected physicochemical and functional properties. The optimal chitosan production may vary depending on the intended final usages in food systems as demonstrated by functional properties from this study.

The effects of plant source cooking oils on cholesterol oxidation during heating in cholesterol standard and salmon meat model were investigated. A GC-MS system was used to identify and quantify of cholesterol and cholesterol oxidation products. The capabilities of different plant source cooking oils in preventing cholesterol oxidation were compared. Commercial plant oils used in this experiment included corn oil, canola oil, olive oil, soybean oil, and rice bran oil. Two lab prepared crude soybean and rice bran oils were also used in this study to evaluate their capabilities of preventing cholesterol oxidation. The tocopherols and tocotrienols antioxidants in those oils were measured by a HPLC system as well. In both cholesterol and salmon meat models, it was found that the cholesterol level decreased with increasing heating temperature and time. The cholesterol decreasing in the salmon meat model was not as fast as in the cholesterol model. Ketocholesterol was the major cholesterol oxidation product in the two models. Soybean oil had the highest capability in preventing cholesterol oxidation, while rice bran oil had the lowest capability among these oils. The soybean oil had the highest alpha and gamma-tocopherol levels, which were considered to be the major antioxidant components of preventing cholesterol oxidation. The commercial oils had lower level of tocopherol and tocotrienol than the lab prepared oil due to the loss of those antioxidants during oil refining procedures. The different capacities between lab prepared soybean oil and rice bran oil in salmon samples were not as significant as in cholesterol model since the salmon meat may contain antioxidants in itself and reduce the total amount of cholesterol oxidation.

Listeria monocytogenes, a ubiquitous foodborne pathogen, was recognized over 70 years ago. It is the source of the human disease listeriosis. The majority of Listeria monocytogenes that have been isolated from food product or human cases are of the serotypes ½ a, ½ b and 4b. Due to the recent outbreaks, recalls and deaths associated with Listeria monocytogenes in ready-to-eat meat products, the United States Department of Agriculture (USDA), Food Safety and Inspection Service (FSIS) on October 2, 2003 issued a directive for the control of Listeria monocytogenes on ready-to-eat products. The ready-to-eat food industry must impose a post-lethality treatment and/or growth inhibitor for Listeria monocytogenes on ready-to-eat products. The purpose of this study was to assess the use of different antimicrobial treatments for the inhibition of Listeria monocytogenes on the surface of food products. The utilization of natural ingredients such as cranberries as well as chemicals such as acidified sodium chlorite was employed. An edible film made of chitosan that was dissolved in acetic acid and lactic acid was also evaluated. The survival of Listeria monocytogenes at freezer temperatures on a variety of ready-to-eat meat products was also assessed. Our study has been successful in understanding the survival of Listeria monocytogenes at freezer temperatures on the surface of ready-to-eat meat products under vacuum and non-vacuum package storage conditions. It has also been observed that the use of cranberry juice, acidified sodium chlorite, and chitosan have great potential antimicrobial properties that can be employed by food processors.

The Catfish industry faces a problem of off-flavors due to odorous compounds produced by cyanobacteria and blue-green algae. Beta-Cyclocitral imparts a hay-woody odor to pond water and fish tissues. At present there are no reliable pond treatment methods available to control these off-flavors. To monitor the levels of this compound for quality control, rapid, sensitive and inexpensive methods are needed. The major goal of this study was to develop enzyme-linked immunoflow assays based on monoclonal and polyclonal antibodies that are specific and sensitive enough to detect beta-cyclocitral in catfish pond water. Beta-Cyclocitral-PPD conjugate was prepared and used to immunize two chickens and two mice for the production of polyclonal and monoclonal antibodies against beta-cyclocitral respectively. Monospecific polyclonal antibodies were purified from the eggs laid by the immunized chickens, using affinity chromatography. For the production of the monoclonal antibodies, hybridoma cells were made by fusion of myeloma cells and spleen cells of the mice that showed high antibody titer and specificity. Hybridoma cells that secreted high affinity monoclonal antibodies were cloned by the limiting dilution method and at least 10 hybridoma cell lines positive for anti-beta-cyclocitral antibodies were established. Immunochemical methods based on anti-beta-cyclocitral IgY and IgG were developed. The two ELISAs based on IgY and IgG had a limit of detection of 1.0 ng/mL and respective I50 values of 3.93 and 7.98 ng/mL. Two enzyme-linked-immunoflow (ELIFA) assays were developed based on the ELISAs. The ELIFAs were very easy to perform but were less sensitive than the ELISAs as shown by their I50 of 46 ug/mL for the IgY-based ELIFA and 93 ug/mL for the IgG-based ELIFA. Further investigations are required for the more efficient recovery of the monoclonal antibodies, to validate the ELISAs, to improve the sensitivity of the ELIFAs and to determine the potential to adapt the developed assays to a kit format for use by the catfish industry and water treatment industries as well as other aquaculture industries.