Browsing by Subject "food safety"
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Item Attachment and survival of viruses on lettuce (Lactuca sativa L. var. capitata L.): role of physicochemical and biotic factors(Texas A&M University, 2006-10-30) Vega, EverardoEnteric viruses are responsible for a significant amount of foodborne disease in the United States. Foodborne disease associated with enteric viruses has been increasing within the last few years due to technological advances and raised awareness. Salads and salad crops are the principal vector for transmission of enteric viruses. The objective of this study was to determine if viruses are able to attach non-specifically to the surface of lettuce and to determine the forces responsible for non-specific viral adsorption to lettuce. Additionally, the impact of the microbial flora on viral persistence was studied to determine the effect on viruses. The four viruses studied were echovirus 11, feline calicivirus, MS2 and ????X174. The viruses were chosen based on their varying isoelectric points and similar physicochemical attributes. The isoelectric point was not the main factor determining virus attachment to lettuce. Viruses had varying attachment efficiencies, with echovirus 11 having the highest affinity to lettuce and ????X174 the least. Viral adsorption to lettuce was mediated by electrostatic forces due to the removal of virus adsorption at pH 7 and 8 with the addition of 1 M NaCl to the buffer solutions. Microcosm studies indicated that the microbial flora did not have a negative impact on virus survival. The bacteriophages had the highest survival rate. Virus survival in the microcosm studies was not indicative of virus survival on the surface of the lettuce. The animal viruses exhibited survival rates greater than or equal to the survival of bacteriophages at 4???? C, but at room temperature viable animal viruses rapidly declined compared to the bacteriophages. Additional studies also indicated that the microbial flora was not able to degrade the viruses for aerobic microbial growth. Overall, these results indicate that viruses are able to attach to the surface of lettuce, providing a possible explanation for the high incidence of virus associated disease involving salads and fresh produce. More importantly the use of surrogates for virus studies involving fresh produce must be re-evaluated, because of the lack of correlation between animal viruses and bacteriophages. Appropriate viral surrogates, if used, have to be carefully chosen based on viral physicochemical properties as well as the infectious route of the virus.Item Biomarkers of Exposure to Foodborne and Environmental Carcinogens: Enterosorbent Intervention in a High Risk Population(2011-10-21) Johnson, Natalie MalekThe need to assess human exposures to foodborne and environmental carcinogens, particularly in populations at high risk for cancer and disease, has led to the development of chemical-specific biomarkers. Sensitive biomarkers for aflatoxin and polycyclic aromatic hydrocarbons (PAHs) have been useful in providing information on population exposure and reducing associated public health impacts. Aflatoxins are fungal metabolites found in a variety of foods. Among these toxins, aflatoxin B1 (AFB1) is the most predominant and hepatocarcinogenic. Acutely, AFB1 can cause disease and death, necessitating safe and effective intervention strategies. Inclusion of NovaSil (NS) clay in the diet represents a practical, sustainable approach. NS has been shown to prevent aflatoxicosis in multiple animal species by binding aflatoxins in the gastrointestinal tract, reducing toxin bioavailability. Co-exposure to PAHs, hazardous environmental contaminants, has been shown to increase the risk for hepatocellular carcinoma (HCC). Therefore, objectives of this research were to utilize biomarkers to assess aflatoxin and PAH exposures in susceptible populations in Ghana and the U.S. and to evaluate the safety and efficacy of NS intervention in Ghana (a population at risk for aflatoxicosis). After 3-month intervention with 3.0g NS/day, median aflatoxin M1 (an AFB1 metabolite) was significantly reduced (up to 58 percent) compared to the placebo group. Furthermore, no significant differences were found in levels of nutrient minerals between NS and placebo groups at baseline and 3-months suggesting NS can be used to effectively sorb AFB1 without affecting serum concentrations of important minerals. PAH biomarker results showed participants in Ghana were significantly exposed to high levels of PAHs based on the presence of 1-hydroxypyrene (1-OHP) in the majority of urines (98.9 percent). NS treatment had no effect on 1-OHP levels, further confirming the preferential binding of aflatoxins by NS. U.S. population data from a Hispanic community in Texas with an elevated incidence of HCC demonstrated a lower percentage and level of aflatoxin and PAH biomarkers. Aflatoxin M1 excretion, however, was associated with increased consumption of certain foods prone to aflatoxin contamination; thus, some individuals may be more vulnerable to exposure and associated interactions that increase the risk for HCC (e.g., PAHs or hepatitis infection).Item Comparison of the Prevalence and Genotypic Characteristics of Clostridium difficile in a Closed and Integrated Human and Swine Population in Texas(2011-10-21) Norman, Keri NoelleClostridium difficile has been recognized as one of the leading causes of nosocomial diarrhea and pseudomembranous colitis in human hospitals and nursing homes since the 1970s; however, recent occurrences of community-acquired cases have led researchers to search for additional sources of these infections. Some of the possible sources being investigated include food animals and retail meat. The objective of this study was to compare the prevalence and genotypic characteristics of C. difficile isolated from a closed population in Texas consisting of both humans and swine. Implicit in this objective, we seek to investigate the possible food safety and occupational risks associated with swine and C. difficile. Isolation of C. difficile was performed utilizing an enrichment technique and restrictive media. Polymerase chain reaction (PCR) was used to test for the presence of the toxin A and B genes, the tcdC gene deletion, and the binary toxin gene. Genotypic characteristics were compared using PCR toxinotyping and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility was tested using commercially available tests (ETest?) for 11 different antibiotics. Statistical comparisons (both parametric and non-parametric, and appropriate to the data) were performed both between and among host species. We tested 2,292 aggregated human wastewater samples and 2,936 swine fecal samples from 2004 to 2006 and found 271 (11.8 percent) and 252 (8.6 percent) to be positive for C. difficile, respectively. The prevalence of C. difficile among swine production groups differed significantly (p<0.05); however, prevalence in the human occupational group cohorts (swine workers and non-workers) did not differ (p=0.81). The majority of the human and swine isolates were a PFGE NAP7 (a variant pattern with 90.5 percent similarity) toxinotype V strain. Antimicrobial resistance levels and multi-resistance patterns were generally similar between host species; however, there was decreased susceptibility (p<0.05) to ampicillin, clindamycin, and imipenem observed in swine isolates, whereas there was decreased susceptibility (p<0.05) to ciprofloxacin in the human isolates. The similarity in C. difficile prevalence between swine workers and non-workers suggests a low occupational hazard of working with swine as it relates to C. difficile source. We also found that there is a decreased prevalence of C. difficile in late production groups in swine suggesting a lowered risk of food-borne exposure. However, the majority of the isolates derived from the human wastewater and swine appeared to be of very similar strain types, suggesting that a common environmental point source predominates for both hosts.Item Consumers' Dependency on Media for Information about Food Safety Incidents Related to the Beef Industry(2012-10-19) Charanza, AshleyFood safety has become an important topic in today's mainstream media. Food safety incidents, specifically related to the beef industry, have the potential to damage the beef industry severely, and negative coverage in the media can alter consumers' perceptions and attitudes toward the beef industry. This study examined consumers' media dependency during normal times when a food safety incident is not occurring or is not expected to occur and during times of a potential food safety incident. This study also compared rural, urban, and suburban respondents' media dependencies and described consumer perceptions of the beef industry. The target population was Texas A & M University former students registered with a valid email address in a database maintained by The Association of Former Students. An online questionnaire was created on surveymonkey.com and sent to respondents over a four-week time period. Most of the respondents were educated, married, 50 years of age, and had some agricultural experiences. Respondents reported using more media during normal times than during a potential food safety incident. There was a level of concern among respondents toward aspects of the beef industry, such as use of antibiotics and growth hormones, and some concerns about respondent's health being affected by a food safety incident. The researcher concluded that respondents use multiple mediums to receive information about any issue; therefore agricultural communicators should target consumer messages to multiple mediums. Messages also should be constructed to address concerns with the beef industry to ensure consumers that the beef food supply is safe. It was recommended that similar research be conducted during or immediately after a national food safety incident, and research could be conducted on a different population.Item Radiosensitization Strategies for Enhanced E-beam Irradiation Treatment of Fresh Produce(2011-08-08) Gomes, CarmenFresh produce is increasingly implicated in outbreaks of foodborne illness. Internalization of bacterial pathogens into produce is of particular concern as internalized pathogens are unlikely to be removed by surface sanitizers. It is therefore necessary to develop treatments that will reduce their prevalence and numbers on fresh produce. Irradiation is a penetrating nonthermal treatment that effectively eliminates bacteria. Irradiated baby spinach leaves up to 1.0 kGy showed negligible (P>0.05) changes in color, texture, vitamin C, total carotenoids, and chlorophyll content compared to non-irradiated controls throughout storage (15 days at 4oC). This research also shows that irradiation effectively reduces viable Escherichia coli cells internalized in lettuce, and that decontamination is not influenced (P>0.05) by lettuce variety. Irradiation effectively reduced the population of internalized pathogens in a dose-dependent manner (3-4 log reduction at 1.0 kGy). Microscopy images suggest that the contamination sites of pathogens in leafy vegetables are mainly localized on crevices and in the stomata. A careful design of the treatment (understanding dose distribution) will effectively eliminate pathogens while maintaining produce quality. The use of modified atmosphere packaging increased (P<0.05) the sensitivity of pathogens (Salmonella spp. and Listeria spp.) to irradiation in baby spinach leaves (up to 25%). Increasing concentration of oxygen increased (P<0.05) sensitivity of both microorganisms. Radiosensitization could be affected (P<0.05) by production of ozone, which increases with increasing dose-rate and oxygen concentration, and reducing temperatures. Antimicrobial effectiveness of various active compounds was determined against Salmonella spp. and Listeria spp. Inclusion complexes were prepared with antimicrobial compounds and -cyclodextrin. The effectiveness of the microencapsulated compounds was tested by spraying them on the surface of baby spinach leaves inoculated with Salmonella spp. The increase in radiosensitivity (up to 40%) varied with the antimicrobial compound. Spherical poly (DL-lactide-co-glycolide) (PLGA) nanoparticles with entrapped eugenol and trans-cinnamaldehyde were synthesized for future antimicrobial delivery applications. All loaded nanoparticles proved to be efficient in inhibiting growth of Salmonella spp. and Listeria spp. The entrapment efficiency for eugenol and trans-cinnamaldehyde was 98% and 92%, respectively. Controlled release experiments (in vitro at 37oC for 72 hrs) showed an initial burst followed by a slower release rate of the antimicrobial entrapped inside the PLGA matrix.Item Use of Disinfectants and Cleaners to Reduce Bacteria on Poultry Transportation Coops with a Compressed Air Foam System(2013-05-24) Hinojosa-Garza, Carolee A.Poultry transport coops are rarely washed and demonstrate to be a major point of broiler carcass contamination. Our laboratory hypothesized that foaming disinfectants and cleaners commonly used within processing plants may be used to clean and disinfect poultry transport coops. The objective of this study was to evaluate treatments consisting of a low-pressure water rinse (LPWR), a foaming additive alone, foaming cleaner or peroxyacetic acid with a foaming additive to reduce bacteria on broiler transport coops. A high-pressure water rinse (HPWR) applied prior to and following treatments was also evaluated. Homogenized feces was evenly applied to the floors of pre-cleaned transport coops and allowed to dry. The first study used fresh layer feces and evaluated the treatments ability to reduce aerobic bacteria from the manure. The second study added a HPWR step to determine whether this technique would reduce bacteria. In the third study, Salmonella Typhimurium was added to the homogenized fecal slurry to evaluate how effectively these methods reduce aerobic bacteria and Salmonella on coop surfaces. The field study utilized laboratory treatments proven to be most effective on freshly soiled broiler integrator coops. All foaming treatments were applied using a compressed air foam system (CAFS) using a 1 inch fire hose. Ten minutes post-treatment, all surfaces were rinsed with a LPWR for 30 seconds to remove residual disinfectant. Samples were collected from the transport coops prior to and following treatments utilizing a flame sterilized 5 x 5 cm stainless steel template and a gauze swab pre-applied with buffered peptone water. All samples were stomached, serially diluted, spread plated onto agar plates, incubated for 24 h at 37? C and enumerated. The foam cleaner and peroxyacetic acid with a foam additive significantly reduced (P < 0.05) aerobic bacteria up to 4.84 to 5.17 logs, respectively when compared to the LPWR. The addition of a HPWR following product application significantly reduced bacteria on integrator coops, in the field study, but didn?t improve efficacy of our treatments in laboratory trials. These data suggest that a CAFS may be used in combination with disinfectants and cleaners to reduce bacteria on poultry transport coops.