The antibacterial properties of copper ions against Listeria spp., Pseudomonas spp., Escherichia coli and other coliforms, and total aerobic bacteria have been investigated in seafood processing environments. Our hypothesis was that drains fabricated from copper and coatings and concrete containing copper ions that have been used for sealing floors and walls could be utilized in crawfish and crab processing facilities as an effective means of controlling Listeria spp. and other unwanted bacteria. Copper in the form of copper sulfate pentahydrate was incorporated into coatings and concrete at the salt concentration of 25 ppm (6.36 ppm Cu++). Sampling sites were selected in multiple areas of the processing facilities. Sampling was performed in the course of two-month seafood production period. Bacterial counts were determined by using microbiological selective media. In addition, PCR analysis was applied to detect the presence of Listeria monocytogenes in the environmental samples. Copper drains were found to be quite effective against some of the tested bacteria. The counts of Listeria spp. and total aerobic bacteria were over one log CFU/cm2 lower on the copper drains than those detected on the control sites. Neither copper coatings nor copper concrete exerted antimicrobial activity against any microorganisms tested. Additionally, almost all PCR samples were negative for the presence of Listeria monocytogenes, suggesting that black colonies grown on Oxford media represented the other species of Listeria family. Based on the overall results, the copper-fabricated drains could be used in the seafood processing facilities as one of other approaches for reducing environmental contamination by foodborne pathogens. Regarding the application of copper coatings and concrete at the seafood production plants, future research should be conducted to find the most effective bactericidal copper forms and, subsequently, their effective minimal inhibitory concentrations.

Escherichia coli O157:H7 is an emerging food pathogen that was first identified as a cause of illness in 1982. According to CDC (The Center for Disease Control and Prevention) estimates, E. coli O157:H7 is responsible for about 73,000 illnesses, 2,000 hospitalizations and 60 deaths in the United States each year. Cattle are the principal reservoir of E. coli O157:H7. Contamination of feed and drinking water with cattle feces is an importance factor in the prevalence of infection in cattle which, in turn, results in contamination of food and the environment. Escherichia coli O157:H7 is a very persistent pathogen and has been shown to survive for long periods of time in the cattle farm environments. The purpose of this study was to test for the presence of E. coli O157:H7 in cattle water troughs of four cattle farms in Louisiana and also to study the survival and growth characteristics of different strains of E. coli O157:H7 in cattle water trough sediments using experimental microcosms. Escherichia coli O157:H7 can form biofilms on food contact surfaces and is responsible for several outbreaks caused due to cross-contamination in food processing plants. An additional objective of this study was to investigate the antimicrobial effects of cetylpyridinium chloride (CPC) against E. coli O157:H7 biofilms grown on stainless steel surfaces in different temperature and culture conditions. Results from this study showed an E. coli O157:H7 prevalence of 4.5% in the cattle water troughs. Survival studies showed variability in the growth of E. coli O157:H7 at different temperatures. Higher temperatures (25°C and 37°C) resulted in greater decrease of E. coli O157:H7 than at lower temperatures (5°C and 15°C), especially in the presence of natural microflora. It was also observed that the growth and survival of human E. coli O157:H7 isolates was significantly lower than environmental isolates at lower temperatures (5°C and 15°C). The biofilm study showed that <1.0% CPC was effective in inactivation of E. coli O157:H7 biofilms grown on stainless steel in all treatment conditions.

Recent studies have suggested that the health promoting capabilities of oats are due to its antioxidants (tocopherols, tocotrienols, and sterols) found within the bran along with phenolic compounds, such as avenanthramides, p-hydroxybenoic acid and vanillic acid. Long-chain fatty acid oxidation is directly responsible for most off-flavors in food. Since oat bran is a good source of antioxidants, a concentrated extract could be used as a natural preservative, for foods rich in unsaturated long-chain fatty acids. Three methods, traditional solvent (TSE), microwave-assisted solvent (MAS), and supercritical fluid treatment (SFT), were used to obtain the extracts. One extraction temperature in TSE, 60°C, and two extraction temperatures in MAS, 60°C and 100°C, were tested. The DPPH (2, 2'-diphenyl-1-picrylhydrazyl) method demonstrated that the MAS-100°C was the most efficient extraction in the group, thereby serving as MAS sample against the TSE and supercritical-treated samples. For the treated samples, oat bran was exposed to supercritical CO₂ before extraction. Three different temperatures of CO₂ were tested, 25°C, 50°C, and 75°C. The treated samples then underwent MAS-100°C to gather extracts for analysis. The experimental results for the DPPH test favored the SFT-75°C treatment at a 40μl concentration. Therefore, SFT-75°C served as the treated sample in the final three experiments. Antioxidant activity was further tested using two other methods: cholesterol oxidation and the DHA model. The total phenolic content was determined using Folin-Ciocalteau Method. The SFT-75°C treatment showed statistically higher results for antioxidant activity in both the cholesterol oxidation and DHA oxidation experiments over the TSE-60°C or MAS-100°C. In terms of total phenolics, the SFT-75°C treatment showed statistically higher results than TSE or MAS-100°C in terms of catechin equivalency, but no statistical difference was seen among the treatments when compared on the basis of total phenolics per gram of original oat bran sample. However, extraction techniques can be evaluated based on extract yield, which this research demonstrated would be SFE-75°C. In conclusion, the SFT-75°C treatment was the optimal extraction based on antioxidant activity, catechin equivalency for total phenolics, and sample yield. This information could be used in the future development of food products as a natural antioxidant source.

In the last few decades, fresh-cut fruit products have gained popularity with consumers. They require little to no further processing prior to consumption. Fresh-cut products also make fruits and vegetables more conveniently available to consumers year-round. There are limitations, however, to fresh-cut fruit and vegetables in the marketplace. These products are very perishable and could become contaminated with foodborne pathogens. Most fresh-cut fruits and vegetables will only last a short period of time at refrigerator temperatures. There are many possible routes of bacterial contamination in the fresh-cut produce industry. There is a need for antimicrobial compounds that can be applied to fruits and vegetables to help maintain the shelf-life of these products without greatly altering their sensory qualities. Cetylpyridinium chloride (CPC) and acidified sodium chlorite (ASC) have both been shown to have antimicrobial effects. This study was conducted to determine if cetylpyridinium chloride and acidified sodium chlorite would be effective in reducing E. coli 0157:H7, Salmonella Montevideo, and Shigella sonnei on the surface of inoculated and stored fresh-cut cantaloupe cubes. The effect of these compounds on the physiological quality of fresh-cut cantaloupe cubes was also investigated. Results obtained from this study show that both compounds were effective in significantly reducing the three pathogens. Significant reductions were achieved during both a preliminary 24 hour storage study and a 12 day shelf life study for all three pathogens. The 1.00% CPC and 1000 ppm ASC concentrations were most effective at reducing the three pathogens. It was also determined that CPC and ASC did not greatly affect the physiological quality (°Brix, firmness, color) of fresh-cut cubes stored at refrigerator temperatures for up to fourteen days. Treatment of fresh-cut cantaloupe cubes with CPC caused significant interaction effects between treatment levels and sampling day on the recovery of several characteristic impact flavor and aroma compounds (CIFAC). Concentrations of ASC caused significantly higher levels of certain volatiles to be recovered over the 14 day study.

Dietary salt restriction is a common approach recommended by physicians in the treatment and prevention of hypertension. Salt substitute is a potential alternative. The most popular salt substitute is KCl, having similar physical properties to NaCl. Because of the higher molecular weight of cations (K+), KCl imparts undesired bitterness and metallic aftertaste. L-arginine has been found to have the bitterness-suppression property. Therefore, it may be used in the mixture of salt substitutes. In the first study, NaCl and four salt substitute solutions consisting of KCl, NaCl, and L-arginine, were developed at 0.5%, 1%, and 1.5% w/v. A discriminative test was performed to determine (1) the effectiveness of L-arginine in masking the bitterness perception of KCl, (2) saltiness perception of mixed salt solutions against NaCl solution, and (3) sensitivity of the simple ranking test vs. the R-index tests for evaluating bitterness and saltiness perception. The differences of saltiness perception of aqueous mixed salt against NaCl solution existed based on the non-parametric Friedmans test and the R-index test. The samples were not significantly different in terms of bitterness based on both techniques. Therefore, L-arginine could mask the bitterness of KCl. In study two, eleven formulations of the mixture of NaCl/KCl/L-arginine were developed using a mixture design. The consumer study was performed to determine sensory attributes driving acceptance and to optimize the formulation. Consumers (n=385) evaluated the products, following a balanced incomplete block design. Bitterness was the discriminating attribute. Overall liking was identified as the attribute influencing consumer acceptability. The formulation containing 56-100% NaCl, 0-44% KCl, and 0-5% L-arginine would yield product acceptability score 1.0 unit less than that of NaCl. Consumers were able to discriminate the saltiness and the bitterness between formulations of salt solutions (100% NaCl vs. 35% NaCl, 65% KCl), using the triangle test with a corrected beta binomial distribution. L-arginine could partially mask the bitterness of KCl. However, development of the proportion of KCl/NaCl/L-arginine obtained from mixture design, and the application of salt substitute in foods would be worth further study. Moreover, the heat and cold stability of L-arginine in the salt substitutes should be investigated.

ABSTRACT Solvent extraction methods are widely used for extracting antioxidant in foods and other sources. In this study, Traditional Solvent Extraction (TSE) and Microwave-Assisted Solvent Extraction (MASE) were utilized to determine the content of antioxidants in corn germ, wheat bran and wheat germ. Corn germ, wheat bran and wheat germ all contain different levels of antioxidants; TSE and MASE were utilized to determine the content of antioxidants in these three samples. TSE was performed at 60 ¨¬C employing three solvents, acetone, hexane and methanol. MASE was performed using the solvent methanol at four different temperatures, 60, 80, 100 and 120 ¨¬C. DPPH (2,2-Diphenyl-1-picrylhydrazyl) Assay was used to determine antioxidant capacity. For all samples, the most antioxidant capacity extracted using the TSE was achieved using methanol as the solvent, results ranged from 0.42-4.69 nmol Trolox/g. Using acetone and hexane as solvents for TSE yielded much lower antioxidant capacities. The MASE demonstrated consistent results compared with the TSE using methanol. In regard to wheat bran and corn germ, the capacity for antioxidants and phenolics content improved with each increase in temperature. Wheat germ yielded 3.36-3.88 nmol/g for the DPPH assay and 1248-1575 ¥ìg catechin equivalents /g for phenolics assay establishing wheat germ as containing the most antioxidant contents of the three samples. Corn germ and wheat bran displayed antioxidant capacities on a much smaller scale. The sample of corn germ¡¯s antioxidant capacity had a range of 0.90-1.19 nmol/g and 539-730 ¥ìg catechin equivalents /g, and wheat bran¡¯s antioxidant capacity and phenolics ranged from 0.39-0.72 nmol/g and 318.2-489.5 ¥ìg catechin equivalents /g. Both extraction methods were found reliable for determining the antioxidant contents of grains when methanol was employed.

Vibrio vulnificus (Vv) is a natural occurring bacterium of world wide estuarine environments, which concentrate on filter feeding shellfish. Under cooked seafood contaminated with this pathogen is a leading cause of 95% of seafood-related, foodborne deaths. The development of a rapid, reliable and user-friendly method for Vv enumeration would help to reduce mortality rate. A direct colony immunoblot (DCI) method was developed and used as a rapid enumeration with high sensitivity and the specificity. This method was optimized using Vv agar plates incubated for 16 h at 35 °C. Colonies were transferred from incubated plates to polyvinylidene fluoride (PVDF) membranes and treated with rabbit antiflagellar Vv antibodies for 1 h, then washed 3 times. The membranes were then incubated with peroxidase-conjugated goat anti-rabbit IgG for 1 h, and washed 3 times. Finally, the color development mixture was added (Tris buffer, 3, 3-diaminobenzidine, NiCl2 and H2O2) for 5 min. Positive colonies produced a purple color. Total time duration for enumeration of Vv by the DCI was 3.5 h. The DCI method was compared with the FDA recommended DNA probe hybridization (DNAH) method (6-10 h) and most probable number MPN method (50 h) for enumeration of naturally occurring Vv in oysters. There was no significant difference between the DCI and DNAH methods at 0h, 4h, 8h, 12h and 24h, with both methods having Vv counts of about 2.90 Log CFU/g. By day 7 there was a significance difference between the two methods, with the DNAH exhibiting higher Vv counts (2.62 Log CFU/g) compared to the DCI (2.22 Log CFU/g). By 14 days the counts for both methods were not significantly different from each other (1 Log CFU/g). The DCI method exhibited comparable Vv counts in raw oysters compared with those of the DNAH method except for day 7, which may be due to false positive colonies detected by the DNAH method. The DCI could be a more reliable, inexpensive, rapid and user-friendly method for enumeration of Vv in raw oysters. This could possibly be used as a rapid enumeration method by regulatory agencies or the seafood industry.

This study assessed the effects of amino acid additives, aspartic acid, leucine, lysine, and methionine, on the pasting and thermal characteristics of white-fleshed and orange-fleshed Beauregard sweet potato starches. Also, the white-fleshed and the orange-fleshed sweet potato starches were compared for any differences in their resistant starch and crystalline properties. This study was performed using Differential Scanning Calorimetery (DSC), Rapid Visco Analysis (RVA), X-ray Diffraction (XRD), and Resistant Starch Determination. The orange-fleshed starch granules began to gelatinize at a lower temperature (56.8°C) than the white-fleshed starch (70.1°C), but the two starches needed the same amount of energy to gelatinize. Lysine increased the gelatinization temperature of the orange-fleshed starch. The addition of lysine and aspartic acid increased the gelatinization temperatures of the white-fleshed starch. In comparing pasting characteristics, the orange-fleshed starch was found to be easier to cook, had a lower potential for retrogradation, and was less stable during heating than the white-fleshed starch. The RVA analysis showed that the charged amino acids, aspartic acid and lysine, had more of an affect on the two starches than did the neutral amino acids, leucine and methionine. Aspartic acid had similar effects on both starches, making them less stable during cooking and lowering the potential for retrogradation. Lysine, when added to the orange-fleshed sweet potato starch, decreased the breakdown, allowing for more stability during cooking. The results of the resistant starch determination revealed that the white-fleshed sweet potato starch had significantly more resistant starch than the orange-fleshed starch in gelatinized and ungelatinized forms. Lysine increased the amount of resistant starch in the orange-fleshed starch, while leucine and methionine decreased the resistant starch in the orange-fleshed and the white-fleshed starches, respectively. The crystallinity patterns of the white-fleshed and orange-fleshed sweet potato starches were found to be the A-type pattern before gelatinization, and the B-type pattern after gelatinization. The addition of aspartic acid and methionine did not alter the crystalline pattern of either of the starches and caused a decrease in crystallinity, while the addition of leucine and lysine increased the crystallinity of the white-fleshed sweet potatoes.

Vibrio vulnificus is an estuarine bacterium that can cause primary septicemia as well as other serious wound infections. Vibrio parahaemolyticus is a gram-negative, halophilic bacterium that may cause gastroenteritis, diarrhea, headache, vomiting, nausea, abdominal cramps and is the leading cause of gastroenteritis in United States. Consumption of raw oysters is believed to closely relate with infection with Vibrio vulnificus and Vibrio parahaemolyticus. All strains of V. parahaemolyticus produce tlh genes and the major virulence factors of V.parahaemolyticus are the tdh and trh genes. This study was conducted to determine if Vibrio vulnificus and Vibrio parahaemolyticus clinical and environmental strains display different behaviors at refrigeration temperature. The effects of three different temperature treatments were investigated in this study. In addition, the cold adaption behaviors of different gene-containing Vibrio parahaemolyticus in broth under three different temperatures 5, 8, and 10oC were also studied. Results obtained from this study showed clinical and environmental strains of Vibrio vulnificus and Vibrio parahaemolyticus in oysters had significant differences in growth and survival at specific days under different refrigeration temperature treatments. When different gene-containing Vibrio parahaemolyticus strains were stored at 5oC over 10 days, all strains were able to survive but not grow. At 8oC all of the V. parahaemolyticus strains were able to survive and grow. At 10oC, two of the V. parahaemolyticus strains survived and grew while the V. parahaemolyticus 132 X 5 strain survived but did not grow.

In this study, the effects of ozonation and the addition of amino acids on rice starches were determined in terms of pasting properties by using rapid visco-analyzer, thermal characteristics by using differential scanning calorimeter, crystallinity by using x-ray diffraction, and resistant starch yield. Results from viscosity analysis showed that the addition of lysine (6%) to ozonated Sigma rice starch significantly reduced peak viscosity (PV), minimum viscosity (MV), final viscosity (FV), and setback (SBK) by 918, 1024, 1023, and 105 cP, respectively. Moreover, it decreased pasting time, resulting in the faster swelling upon heating and less rigid gel formation upon cooling. The presence of lysine in ozonated white starch isolate (WSI) also significantly reduced all pasting properties and time to cook, and produced starch gel with the best cooking stability. The amylose content of Sigma rice starch was increased by ozone, and the enzymatic-gravimetric analysis indicated that the resistant starch yield was enhanced by more than 3% when rice starch was ozonated for 30 minutes. Moreover, the addition of leucine to ozonated starch showed the highest resistant starch formation (9.13%). Ozonation of Sigma rice starch and white starch isolate (WSI) reduced gelatinization temperature, amylose-lipid complex endothermic temperature and enthalpy, but increased 1st transition enthalpy. However, the presence of lysine (6%) increased gelatinization endotherm transition temperature but reduced 2nd transition enthalpy. Ozone treatment of Sigma rice starch induced B+V type XRD pattern and increased the relative crystallinity (RC), and addition of lysine showed A+B type XRD pattern and enhanced the RC further. In addition, ozonation caused some physical damage showing some broken small pieces of particles and distorted starch granules with both Sigma rice starch and white starch isolate.