Pulsed electric field (PEF) treatment is a non-thermal and alternative pasteurization treatment for fruit juices. PEF applies short pulses of electricity to a liquid food sample which inactivates microorganisms and enzymes. Thermal pasteurization is commonly used to pasteurize juice in the fruit juice industry but the process tends to deteriorate color, nutrients, and overall juice appearance. The overall goal of this study was to determine the effects of PEF treatment (30 kv/cm for 57 ìs in bipolar 2 ìs pulses at 22°C) on color, lycopene content, vitamin C content, pH, °Brix, and microbial count when compared with the effects of thermal pasteurization (TP). Fresh watermelon juice was PEF-treated at the following flow rates (mL/min), 60, 80, 100, 120, 140, and 160, while the TP-treated juice was thermally pasteurized with the following conditions: 75°C at 15, 30, and 45 s; 80°C at 15, 30, and 45 s; 85°C at 15, 30, 45 s; 90°C at 15, 30, and 45 s. Vitamin C degradation was modeled and estimated for TP watermelon juice samples using Power Law and Arrhenius models. A fresh, untreated watermelon juice sample was used as the control for the TP treatments. Watermelon juice was passed through the PEF system without pulse application and used as a PEF-control. Triplicate experiments were conducted. For PEF treatments, lycopene content was significantly higher at the slowest flow rate of 60 mL/min. Vitamin C of watermelon juice was not significantly affected during PEF treatment regardless of the flow rate, while it significantly decreased (P < 0.05) with intensity of TP treatments. The reaction rate constant (K) of watermelon juice for TP treatment at 75°C was significantly less than juice sample treated at 80, 85, and 90oC, which indicated that the Power law model worked well at higher temperature TP treatments. This model was more appropriate for predicting vitamin C concentration of watermelon juice during thermal pasteurization. The calculated activated energy for the vitamin C degradation for TP vii treatments was 5.54 (kJ/mol), which was lower than the reported values for other juices. TP-treated juice had higher b*values than PEF-treated juice which indicated TP juice was more yellow in color. PEF treatments did not affect the pH of the juice compared to TP treatments which increased pH. PEF-control and PEF-treated samples had similar °Brix values. TP treatments significantly affected °Brix values of watermelon juice. These results indicate that PEF treatment is a better option for pasteurizing watermelon juice over TP in terms of lycopene, vitamin C content and color.

Defatted rice bran (DRB) is a byproduct of rice milling and rice bran oil extraction. Soluble rice bran fiber (SRBF) extracted from defatted rice bran is known for its antioxidant activity and hypocholesterolemic effects in human, while purified menhaden oil (PMO) is a good source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The goal of the study was to estimate optimum extraction conditions to extract SRBF from DRB, develop a cost effective method to purify SRBF and produce microencapsulated PMO with SRBF. The response surface methodology showed that an estimated optimum yield of SRBF (7.89%) could be extracted from DRB with 3% Ca(OH)2 solution to DRB ratio 29.75:1 and stirred for 1 hr at 84oC and also Ca(OH)2 solution concentration was the most effective factor among the conditions used to extract SRBF. Our study showed that conventional processing steps, such as dialysis and alcohol precipitation, for removing mineral and monosaccharides and other small molecules from SRBF, could be replaced with the ultrafiltration technology. The ultrafiltration for purifying SRBF solution at 100 kPa with 10 kDa MWCO membrane required less time than filtering the solution at the same pressure with 1 and 5 kDa MWCO membranes. The estimated microencapsulated PMO with SRBF powder (MFMO) production rate using spray dryer was 3.45 * 10-5 kg dry solids/s and was higher than the actual production rate 2.31 * 10-5 kg dry solids/s. The energy required to increase the inlet ambient air temperature from 27.1 to 180 oC and evaporation rate for spray drying the emulsion was 2.78 kJ/s and 7.8 * 10-3 kg water/s, respectively. EPA and DHA contents of MFMO were 11.52% and 4.51%, respectively. The particle size of 90% MFMO ranged from 8 to 62 um, and the volume-length diameter of MFMO was 28.5 um. The study demonstrated that optimum extraction conditions for extracting SRBF from DRB could be achieved through the response surface methodology, conventional purification steps of SRBF including dialysis and alcohol precipitation could be replaced with ultrafiltration technology, and the MFMO could be provided with potential health benefits for humans.

Crawfish and shrimp byproducts are an excellent source of astaxanthin. The antioxidant-rich natural astaxanthin dispersed in alpha linolenic acid-rich flaxseed oil (FO) may provide healthier functional food options for US consumers. The goals of this study were to extract astaxanthin from crawfish and shrimp byproducts and to develop astaxanthin dry powders using microencapsulation technology. Astaxanthin extracted with FO from crawfish (FOCA) and shrimp (FOSA) byproducts were stable at 30 and 40 , but had substantial degradation at 50 and 60 during four 4 h heating. The astaxathin degradation of FOCA and FOSA fitted with zero and first orders kinetics showed that the rate constant for astaxanthin degradation of FOCA and FOSA increased with increased temperature and first order kinetics could be used to describe the degradation of astaxanthin in FOCA and FOSA between 30 to 60 , while zero order kinetics might describe the astaxanthin degradation in FOCA and FOSA at 60 . The emulsions prepared with FOCA (ECA) and FOSA (ESA) were spray dried to produce microencapsulated powders containing FOCA (MCA) and FOSA (MSA) using a pilot scale spray dryer. The energy required to spray dry 0.433 kg ECA and 0.428 kg ESA was 10220 and 10280 kJ, respectively. The astaxanthin concentration of MCA and MSA was 13.76}0.37 and 16.08}0.24 Êg/g powder, respectively. Alpha-linolenic acid (ALA) was the predominant fatty acid in MCA and MSA, which accounted for 56.32 % and 55.47 % for MCA and MSA, respectively. The lipid oxidation of MCA and MSA was lower at 5 storage than those at 25 and 40 during 26 days storage. Degradation of astaxanthin in MCA and MSA fitted with first order reaction kinetics model showed that the degradation rate constants for MCA and MSA increased with increased storage temperature. This which indicated that astaxanthin degraded faster at higher temperature than that at lower temperature. This study demonstrated that astaxanthin extracted from crawfish and shrimp byproducts using flaxseed oil can be microencapsulated using spray drying technology.

Mineral oil (MO) is currently used for coating eggs to preserve quality. Chitosan possesses inherent antimicrobial and film-forming properties. Chitosan coating (CH) is dried much faster than MO when applied on egg shell. Information on synergistic effects of MO:CH emulsion coatings on egg quality does not exist. We developed MO:CH emulsion coatings, and evaluated their effects on internal quality and shelf-life of eggs during storage. In the first study, MO, CH and three emulsions (MO:CH = 75:25, 50:50, and 25:75) were evaluated during 5 weeks at 25°C. Haugh unit (HU) and yolk index values decreased whereas weight loss increased during storage. Noncoated eggs changed from AA to C grade after 3 weeks. However, all emulsion-coated eggs maintained an A-grade for 4 weeks. All emulsion-coated eggs had weight losses <1.5%. Only 25:75 MO:CH emulsion-coated eggs were not sensorially glossier than noncoated eggs. All emulsion-coated eggs had >80% positive purchase intent and were negative for Salmonella spp. In the second study, 25:75 MO:CH emulsions prepared with four different emulsifier types were evaluated during 5 weeks at 25 °C and 20 weeks at 4 °C. All emulsion-coatings minimized weight loss (<1.5%) and preserved internal quality of eggs for at least 3 weeks longer than observed for noncoated eggs at 25 °C. At 4 °C, all coated eggs changed from AA to A grade after 5 weeks and maintained this grade up to 10 weeks with weight losses <2% at refrigeration. The emulsifier type generally did not insert significant effect on the internal quality. In the third study, MO and 25:75 MO:CH emulsion were evaluated during 5 weeks at 25°C using eggs from three different albumen qualities, expresed as HU, before coating: High=87.8 HU, Medium=75.6 HU and Low=70.9 HU. MO and/or 25:75 MO:CH coatings could preserve the internal quality for at least 4 more weeks for High HU eggs; all with weight losses <0.92%). This study demonstrated that MO:CH emulsion coatings could preserve the internal quality of eggs and prolong their shelf life.

Green tea (Camellia sinensis) extract (GTE) is rich in polyphenolic compounds, especially catechins that are potent antioxidants. The antioxidant property of GTE may make it ideal for use as a glazing solution for suppressing lipid oxidation in shrimp (Litopenaeus setiferus) during frozen storage. In this study, GTE was evaluated as a glazing material for shrimp frozen by air-blast (BF) and cryogenic freezing (CF). Two percent, three percent and/or five percent green tea extract solutions (2GTE, 3GTE, 5TGE) were used for glazing. Distilled water glazed (GDW) and non-glazed (NG) shrimp were used as controls. The GTE was characterized by measuring color, pH, &176;Brix, total phenols, % antiradical activity and the individual catechins were identified by HPLC. The freezing time, freezing rate and energy removal rate for freezing shrimp by both freezing processes was estimated. The frozen shrimp samples were stored in a freezer at -21&176;C for 180 days. Samples were analyzed at 1, 30, 90 and 180 days for pH, moisture content, glazing yield, thaw yield, color, cutting force and thiobarbituric acid reactive substances (TBARS). The HPLC analysis of the GTE revealed the presence of catechin and its isomers and the total polyphenol content determined by HPLC was 148.1 ± 2.49 g/l. The freezing time for air-blast and cryogenic freezing was 48.67 ± 2.30 min and 4.83 ± 0.29min respectively. Cryogenic freezing had an energy removal rate (836.67 ± 78.95 J/s) nearly ten times higher than blast freezing (80.26 ± 3.82 J/s). The pH of all samples increased with increase in frozen storage time and there was no significant difference among treatments. Glazed samples had higher moisture content compared to NG shrimp after 180 days storage. Glazing improved the thaw yield of shrimp. GTE was effective in controlling lipid oxidation in shrimp. Cryogenically frozen shrimp glazed with 5 % green tea extract (CF5GTE) had the lowest lipid oxidation at the end of 180 days. Glazing with GTE affected a* and b* values, but had no significant effect on the L* values of shrimp. The cutting force of all NG shrimp was significantly lower than that of glazed shrimp. This study showed that green tea extract could be successfully applied as an antioxidant glaze for frozen storage of shrimp.

Legumes are high in protein and are a good source of fiber and folate. They contain beneficial oligosaccharides, plant sterols and phenolics. The purpose of this study was to demonstrate the health benefits of legumes using the model system Caenorhabditis elegans (C. elegans). Nine legumes (black beans, cranberry beans, dark red beans, great northern beans, large lima beans, lentils, light red kidney beans, navy beans and white kidney beans) were tested in the C. elegans model system. The various legume samples were ground using a centrifugal mill to 0.75mm, suspended in water (1% w/v) solution and autoclaved. C. elegans were prepared using an age synchronized design. The laboratory standard food source Escherichia coli OP50 (E. coli OP50) was used as a control diet after being UV treated. Within the first week of life, the C. elegans received the first legume treatment of 20%, 33.3% and 50% legume material with the remaining amount being E. coli OP50. Pharyngeal pumping rate, a surrogate marker of aging, was counted manually throughout the study. Travel distance data was collected using imaging software. Nile red fluorescence, a marker of fat deposition, was measured using fluorescence microscopy. Pharyngeal pumping rate in the 50% legume diet group was significantly higher than in the control group. The following legumes had a significant increase in pumping rate throughout the study compared to the control: great northern beans, cranberry, lentil and dark red kidney beans. Fat deposition was decreased in C. elegans when fed black and navy bean diets. Travel distance was not significantly different between treatment and control groups. The results suggested the benefits of sustained lifespan and decreased fat deposition in C. elegans when fed a legume diet. The use of legumes in consumer products was evaluated in this thesis. A consumer study was conducted at a local middle school to determine the sensory attributes that are important to consumers. It was determined that strong flavors and seasonings were important to students and hamburgers are acceptable to students that are not 100% beef.

While all seafood has the potential of being associated with foodborne illness, Louisiana blue crabs (Callinectes sapidus) are exposed to Vibrio cholerae, Vibrio parahaemolyticus, Vibrio vulnificus, Listeria monocytogenes and Salmonella species in the estuarine habitat. This study was designed to determine the least amount of time and temperature needed to reduce or eliminate each of the aforementioned bacteria from a single Louisiana blue crab with either boiling or steaming heat treatments. Once the single crab heat treatment studies were completed, the bacteria that showed the greatest thermal resistance, Listeria monocytogenes, and the bacteria most associated with foodborne illness in Louisiana blue crabs, Vibrio parahaemolyticus were inoculated into a serving size of crabs and subjected to heat treatments. The results were based on the amount of bacterial log reduction of each heat treatment time point. Results of the heat treatment experiments were: boil one crab four minutes and cool one additional minute for an internal temperature of at least 79.5° C and a total cooking time of five minutes; steam one crab for five minutes cool two additional minutes for an internal temperature of at least 57° C and a total cooking time of seven minutes; boil four crabs for 10 minutes and cool five additional minutes for an internal temperature of at least 85° C and a total cooking time of 15 minutes; steam four crabs for 15 minutes and cool five additional minutes to reach an internal temperature of at least 85° C with a total cooking time of 20 minutes.

Members of the genus Vibrio are Gram-negative, halophilic bacteria that inhabit warm coastal and estuarine waters worldwide. Among pathogenic vibrios, Vibrio parahaemolyticus is the leading cause of seafood-related illnesses and Vibrio vulnificus causes the highest number of seafood-related deaths in the United States. Moreover, according to the U.S. Centers for Disease Control and Prevention, the incidence of infections of the two vibrios due to the consumption of oysters has shown a sustained increase since 2001, indicating further measures are needed to prevent human Vibrio illness. In this dissertation research, a total of 622 Vibrio isolates, consisting of 252 V. parahaemolyticus and 370 V. vulnificus, were recovered from 82 Louisiana Gulf and retail raw oysters between 2005 and 2006. A selected subset of the isolates (168 V. parahaemolyticus and 151 V. vulnificus) was determined for antimicrobial susceptibility profiles. In addition, V. vulnificus isolates (n = 349) were characterized by the presence/absence of a viuB-associated fragment and genotypes of three biomarkers: the virulence-correlated gene (vcg), 16S rRNA, and the capsular polysaccharide operon (CPS). Then multiplex PCR assays using three biomarkers: vcg, 16S rRNA and CPS, as well as species-specific vvhA were developed to simultaneously detect and characterize V. vulnificus. Finally, loop-mediated isothermal amplification (LAMP) assays were developed and evaluated to detect total or virulent-type V. vulnificus in raw oysters. Compared to PCR, LAMP assay developed were highly specific, sensitive and quantitative. The dissertation research provided comprehensive information on the genotypes, population dynamics, and antimicrobial resistance profiles of the two important vibrios. The rapid, specific, sensitive, and cost-effective molecular detection assays developed provided invaluable tools for the regulatory agencies and seafood industry to facilitate better control of Vibrio in seafood, therefore reducing the incidence of foodborne illnesses and deaths resulted from the consumption of raw oysters.

Protein with essential amino acids is required for recovering, repairing, and building muscles after intensive exercise. A powder produced with egg white (EW) (high quality protein) and fish oil (menhaden (Brevoortia patronus) (MO) oil or salmon oil (SO)) with high DHA and EPA content should be particularly beneficial for athletes. The objective of this study was to develop microencapsulated omega-3 fatty acids fortified EW powders. Two stable emulsions were prepared with 3.43% (MO) or (SO), 56.21% EW, and 40.36% water (E-MO-EW and E-SO-EW). An EW with water solution (without fish oil) (E-EW) was prepared as a control. Two emulsions (E-MO-EW; E-SO-EW) and E-EW solution were separately spray dried at 130, 140, and 150 oC inlet air temperatures producing three microencapsulated menhaden oil fortified EW powders, three microencapsulated salmon oil fortified EW powders, and three egg white powders (dried E-EW). Physical and chemical properties of E-EW, E-MO-EW and E-SO-EW were determined and the energy used to spray dry them was estimated. The powders were analyzed for color, fatty acids methyl esters (FAME), protein, fat, moisture, ash, amino acid profile, minerals, microstructure and particle size. Microencapsulated efficiency (ME) was estimated only for microencapsulated fish oil fortified EW powders. Triplicate experiments were conducted and data statistically analyzed (á=0.05). The actual production rate of powders ranged from 0.056 to 0.060 (kg dry solids/h). More energy was used to spray dry E-EW, E-MO-EW, and E-SO-EW at 150°C than at 130 and 140oC inlet air temperature. The inlet air temperature did not affect the EPA or DHA content of MO and SO or the microencapsulation efficiency. The protein content of the oil fortified powders was lower than that of the dried E-EW powders. Leucine was the main essential amino acid found in all the powders. Most of the powders particles ranged in size from 20 to 30 µm. The study demonstrated that high quality egg white protein with omega-3 can be produced by microencapsulation. Oil fortified egg white powders could provide benefits for athletes who do high intensity exercise. This study also identifies opportunities for development of microencapsulated omega-3 fatty acids fortified egg white powders.

Chitosan is a polysaccharide biopolymer with excellent biocompatibility, biodegradability, and low toxicity, which allows for potential wide applications. Recently, antimicrobial activities of chitosan against foodborne pathogens have been studied; many used disk diffusion to determine the activity. However, this method is unable to obtain minimal inhibitory concentrations (MICs), i.e., not quantitative. The objective of this study was to compare disk diffusion with agar dilution and broth microdilution, two quantitative methods used routinely in clinical laboratories, to determine MICs of chitosan against foodborne pathogens. Five chitosan compounds with molecular weights ranging between 43 and 1,100 kDa were tested against 36 representative foodborne pathogens using the three methods. A water-soluble chitosan (43 kDa) was found to be the most effective one against Escherichia coli O157:H7 and Salmonella enterica, especially using the agar dilution method. The overall agreement of MICs (within 2-fold dilution) between agar dilution and broth microdilution was only 14.6% and MICs determined by broth microdilution were generally lower than those obtained by agar dilution. Among all strains tested, Vibrio spp. strains were most susceptible to chitosan whereas Salmonella serovars were least susceptible. The MIC values by either agar dilution or broth microdilution for Vibrio spp. were at least one dilution level lower than those for other bacteria. The effectiveness of chitosan against Vibrio spp. demonstrated in this study may prompt future applications of chitosan to control Vibrio spp. in foods, particularly raw oysters. The variability shown when different susceptibility testing methods were used suggests the need to apply multiple methods when conducting in vitro antimicrobial susceptibility testing of chitosans.