Publications

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    Peter M Muriana, Dinesh Babu
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    ABSTRACT: Aflatoxins are considered unavoidable natural mycotoxins encountered in foods, animal feeds, and feed grains. In this study, we demonstrate the application of our recently developed real-time immunoquantitative PCR (RT iq-PCR) assay for sensitive detection and quantification of aflatoxins in poultry feed, two types of dairy feed (1 and 2), horse feed, whole kernel corn feed grains, and retail yellow ground corn meal. Upon testing methanol/water (60:40) extractions of the above samples using competitive direct enzyme linked immunosorbent assay, the aflatoxin content was found to be <20 μg/kg. The RT iq-PCR assay exhibited high antigen hook effect in samples containing aflatoxin levels higher than the quantification limits (0.1–10 μg/kg), addressed by comparing the quantification results of undiluted and diluted extracts. In testing the reliability of the immuno-PCR assay, samples were spiked with 200 μg/kg of aflatoxin B1, but the recovery of spiked aflatoxin was found to be poor. Considering the significance of determining trace levels of aflatoxins and their serious implications for animal and human health, the RT iq-PCR method described in this study can be useful for quantifying low natural aflatoxin levels in complex matrices of food or animal feed samples without the requirement of extra sample cleanup.
    Toxins 12/2014; 6(12):3223-3237. · 2.13 Impact Factor
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    ABSTRACT: Deli meat slicers have been implicated in cross-contamination of ready-to-eat (RTE) foods with Listeria monocytogenes that has resulted in several listeriosis outbreaks. We investigated the lethality of moist heat and silver dihydrogen citrate (SDC) sanitizer on Listeria species that were inoculated on stainless steel (SS) and cast aluminum (AL) coupons cut from actual components of a deli meat slicer. The coupons inoculated with Listeria species were subjected to treatments inside and outside of meat slicer using a commercial bread proofer that was operated for 7 h at 66 °C. Post treatment recoveries of the inoculated Listeria from the treated coupons were enumerated using MOX growth medium. All treatments produced significant (P = 0.05) log reductions compared with positive and untreated negative controls. Moist heat reduced the inoculated bacteria to non-detectable levels when the coupons were placed inside the motor compartment of the slicer and the sanitizer plus moist heat gave same results for the coupons placed inside and outside of the slicer. Chemical sanitizer treatment alone showed average log reductions of around 5 CFU/cm2 on AL and SS coupons respectively and the moist heat alone treatment on both AL and SS coupons showed a log reduction of 4.49 and 4.87 when placed externally and above 6 logs when placed inside the motor compartment. Sanitizer plus moist heat treatments showed highest log reductions of Listeria species to non-detectable levels on deli meat slicer components when placed inside or outside the motor compartment of the slicer. Thus the sanitizer and moist heat combination treatments can effectively reduce the Listeria cells attached onto food contact surfaces of a deli meat slicer.
    Food Control 10/2014; 44:227–232. · 2.74 Impact Factor
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    ABSTRACT: Isoflavones are a group of chemicals that are found in legumes, predominantly in soybean and soy products. Soy isoflavones have been a component of the diet of certain populations for centuries. Many health claims have been made for isoflavones including: cancer prevention, alleviation of menopausal symptoms, positive effects on bone health and a lowering of blood lipids leading to lowered susceptibility to cardiovascular disease. However, because of their estrogenic activity ome negative effects of isoflavones have been postulated. This review examines the literature associated with benefits as well as the negative effects of consumption of soy isoflavones. Results in some studies are limited or conflicting, but when viewed in its entirety, the current literature supports the safety of isoflavones as typically consumed in diets based on soy containing products.
    Agriculture, Food and Analytical Bacteriology. 01/2014; 4(2):122-142.
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    ABSTRACT: Growers and processors of USDA certified organic foods are in need of suitable organic antimicrobials. The purpose of the research reported here was to develop and test natural antimicrobials derived from an all-natural by-product, organic pecan shells. Unroasted and roasted organic pecan shells were subjected to solvent free extraction to produce antimicrobials that were tested against Listeria spp. and L. monocytogenes serotypes to determine the minimum inhibitory concentrations (MIC) of antimicrobials. The effectiveness of pecan shell extracts were further tested using a poultry skin model system and the growth inhibition of the Listeria cells adhered onto the skin model were quantified. The solvent free extracts of pecan shells inhibited Listeria strains at MICs as low as 0.38%. The antimicrobial effectiveness tests on a poultry skin model exhibited nearly a 2 log reduction of the inoculated cocktail mix of Listeria strains when extracts of pecan shell powder were used. The extracts also produced greater than a 4 log reduction of the indigenous spoilage bacteria on the chicken skin. Thus, the pecan shell extracts may prove to be very effective alternative antimicrobials against food pathogens and supplement the demand for effective natural antimicrobials for use in organic meat processing.
    Journal of Food Science 11/2013; · 1.78 Impact Factor
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    ABSTRACT: Traceability through the entire food supply chain from conception to consumption is a pressing need for the food industry, consumers and government regulators. A robust, whole-chain traceability system is needed that will effectively address food quality, food safety and food defense issues by providing real-time, transparent and reliable information from beef production through slaughter and distribution to the consumer. Traceability is an expanding part of the food safety continuum that minimizes the risk of foodborne diseases, assures quality and cold-chain integrity. Traceability can be a positive competitive marketing edge for beef producers who can verify specific quality attributes such as humane production or grass fed or Certified Organic. In this review we address the benefits as well as the remaining issues for whole-chain traceability in the beef industry, with particular focus on ground beef for the markets in the United States.
    Meat Science 04/2013; 95(2):137-144. · 2.75 Impact Factor
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    T. Doan, D. Babu, R. Buescher
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    ABSTRACT: This study investigated the inhibition of yeasts in brines from fermented cucumber pickles using 2, 4-hexadienoic (sorbic), hexanoic and (E)-3-hexenoic acids. Native yeast population and chemical composition of commercial brines were analyzed and the minimum inhibitory concentrations of inhibitors on yeast growth were established. Commercial brines were treated with 100-350 ppm of 2, 4-hexadienoic (sorbic), hexanoic and (E)-3-hexenoic acids individually and at 2.5 to 10% salt (sodium chloride) concentrations. Yeast populations in the treated brines were monitored for 30 days of incubation. Hexanoic and (E)-3-hexenoic acids at 350 ppm caused reduction in yeast populations by about 4 and 2 log CFU/ml, respectively, within 24 hours of treatment. However, when brines were treated with 2, 4-hexadienoic acid at salt concentrations of 7.5 to 10%, there were no significant differences noted in yeast inhibition between the three acids. Hexanoic and (E)-3-hexenoic acids at 200 ppm caused longer lasting inhibitory effects (30 days) on yeasts than the traditionally used 2, 4-hexadienoic acid (10 days) in fermentation brine. Thus, the hexanoic and (E)-3-hexenoic acids are potential alternatives to 2, 4-hexadienoic acid for controlling yeasts during storage of spent cucumber fermentation brines.
    Journal of Food Research. 07/2012; 1(3):295-301.
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    ABSTRACT: In order to address the growing demand for more natural poultry products, alkaline phosphates commonly used in chicken breast meat marinades were replaced with plum ingredients and evaluated. For initial sensory evaluation, 200 consumers of chicken were served a small portion of the chicken breast on a plate and were asked to evaluate the product for overall impression, flavor, and texture on a 9-point hedonic scale with 1 = "dislike extremely" and 9 = "like extremely." Also, a 5-point just-about-right (JAR) scale was used on questions about tenderness, juiciness, overall flavor, and saltiness. Both hedonic and JAR demonstrated that the marinades of plum concentrate and the blend of plum fiber and powder were not distinguishable from the control (P > 0.05). Using two different percentages of fiber/powder blend, two different percentages of concentrate, sodium tripolyphosphate (STPP), and no marinade, measurements were made for marinade per cent pickup, thaw loss, and cook loss. Plum concentrate at 1.1% was most similar to STPP in marinade per cent pickup, thaw loss, drip loss, and cook loss. These results show that plum ingredients can potentially be used as a substitute in standard phosphate marinades. PRACTICAL APPLICATION: Consumers are increasingly demanding more natural foods with less artificial additives. This research presents the results of experiments using dried plum ingredients as a substitute for phosphates commonly used in marinades for chicken. Results indicate that dried plum ingredients may be a suitable substitute for phosphates in marinades.
    Journal of Food Science 06/2012; 77(6):S253-7. · 1.78 Impact Factor
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    ABSTRACT: Liquid smoke extracts have traditionally been used as flavoring agents, are known to possess antioxidant properties, and serve as natural alternatives to conventional antimicrobials. The antimicrobial efficacies of commercial liquid smoke samples may vary depending on their source and composition and the methods used to extract and concentrate the smoke. We investigated the MICs of eight commercial liquid smoke samples against Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli . The commercial liquid smoke samples purchased were supplied by the manufacturer as water-based or concentrated extracts of smoke from different wood sources. The MICs of the commercial smokes to inhibit the growth of foodborne pathogens ranged from 0.5 to 6.0% for E. coli, 0.5 to 8.0% for Salmonella, and 0.38 to 6% for S. aureus. The MIC for each liquid smoke sample was similar in its effect on both E. coli and Salmonella. Solvent-extracted antimicrobials prepared using pecan shells displayed significant differences between their inhibitory concentrations depending on the type of solvent used for extraction. The results indicated that the liquid smoke samples tested in this study could serve as effective natural antimicrobials and that their inhibitory effects depended more on the solvents used for extraction than the wood source.
    Journal of food protection 06/2012; 75(6):1148-52. · 1.83 Impact Factor
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    ABSTRACT:   To test the efficacy of four wipe cloth types (cotton bar towel, nonwoven, microfibre and blended cellulose/cotton) with either quaternary ammonia cleaning solution or silver dihydrogen citrate (SDC) in cleaning food contact surfaces.   Swab samples collected from untreated, cloth-treated and cloth disinfectant-treated surfaces were subjected to hygiene monitoring using adenosine triphosphate (ATP) bioluminescence and aerobic total plate counting (TPC) assays.   Adenosine triphosphate measurements taken after wiping the surfaces showed poor cleaning by nonwoven cloths (2·89 RLU 100 cm(-2) ) than the microfibre (2·30 RLU 100 cm(-2) ), cotton terry bar (2·26 RLU 100 cm(-2) ) and blended cellulose/cotton cloth types (2·20 RLU 100 cm(-2) ). The cellulose/cotton cloth showed highest log reduction in ATP-B RLU values (95%) and CFU values (98·03%) when used in combination with SDC disinfectant. Conclusions:  Cleaning effect of wiping cloths on food contact surfaces can be enhanced by dipping them in SDC disinfectant. ATP-B measurements can be used for real-time hygiene monitoring in public sector, and testing microbial contamination provides more reliable measure of cleanliness.   Contaminated food contact surfaces need regular hygiene monitoring. This study could help to estimate and establish contamination thresholds for surfaces at public sector facilities and to base the effectiveness of cleaning methods.
    Journal of Applied Microbiology 04/2012; 113(1):89-95. · 2.20 Impact Factor
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    Dinesh Babu, Peter M Muriana
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    ABSTRACT: Aflatoxin B(1) is an unavoidable natural mycotoxin that enters the food chain by contamination of food grains and feedstuffs, potentially posing carcinogenic risks to animal and human health. Immuno-PCR methods have the potential to address the need of meeting the regulatory limits by detecting trace levels of toxins present in food and animal feeds. This paper describes a real-time immuno-quantitative PCR (RT-iqPCR) assay for quantification of aflatoxin B(1) suspended in methanol:water solution that can also serve as an extraction solvent. Immuno-PCR approaches were examined including direct vs. indirect sandwich assays using monoclonal vs. polyclonal antibodies. Our best approach was obtained using monoclonal antibodies to capture aflatoxin in solution prior to immobilizing the F(c) portion of the capture antibodies onto to protein G magnetic beads. This was followed by the addition of a polyclonal 'signal antibody' tethered with an oligonucleotide template for a subsequent PCR assay. The RT-iqPCR assay described herein leads to the sensitive detection and quantification of aflatoxin B(1) from 10ppb down to 0.1ppb with high correlation (r(2)=0.97) and efficiency (99.5%). The approach also detected the high-dose 'hook effect' phenomenon (excess antigen) which was overcome by the use of dilution protocols to eliminate false negatives that may occur at levels above quantification limits of the assay. The RT-iqPCR approach discussed here is presented as a model system that could easily be adapted for aflatoxin detection in a variety of food or animal feed samples using a simple methanol:water solution as an extraction solvent.
    Journal of microbiological methods 05/2011; 86(2):188-94. · 2.43 Impact Factor
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    ABSTRACT: The potential negative impact of agricultural practices on soil and water quality is of environmental concern. The associated nutrient transformations and movements that lead to environmental concerns are inseparable from microbial and biochemical activities. Therefore, biochemical and microbiological parameters directing nitrogen (N) transformations in soils amended with different animal manures or inorganic N fertilizers were investigated. Soils under continuous corn cultivation were treated with N annually for 5 years at 56, 168, and 504 kg N ha−1 in the form of swine effluent, beef manure, or anhydrous ammonia. Animal manure treatments increased dehydrogenase activity, microbial biomass carbon (Cmic) and N (Nmic) contents, and activities of amidohydrolases, including l-asparaginase, urease, l-glutaminase, amidase, and β-glucosaminidase. Soils receiving anhydrous ammonia demonstrated increased nitrate contents, but reduced microbiological and biochemical activities. All treatments decreased Cmic:organic C (Corg) ratios compared with the control, indicating reduced microbial C use efficiency and disturbance of C equilibrium in these soil environments. Activities of all enzymes tested were significantly correlated with soil Corg contents (P < 0.001, n = 108), but little correlation (r = 0.03, n = 36) was detected between Cmic and Corg. Activities of amidase and β-glucosaminidase were dominated by accumulated enzymes that were free of microbial cells, while activities of asparaginase and glutaminase were originated predominately from intracellular enzymes. Results indicated that soil microbial and biochemical activities are sensitive indicators of processes involved in N flow and C use efficiency in semiarid agroecosystems.
    Applied Soil Ecology. 01/2006;
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    D. Babu, P. Muriana
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    ABSTRACT: Several mold species of Aspergillus produce secondary metabolites called Aflatoxins. These aflatoxins can be carcinogenic and are considered potential threats to human and animal health when ingested. Aflatoxins occur naturally in food and feed products in microgram to milligram per gram of food or feed quantities thus detection methodology should be sensitive and specific which is not obtained with currently available methods. This study involves detection and quantification of aflatoxins in food products and animal feeds. Our research methodology involves use of immunomagnetic beads combined with real time PCR assay using aflatoxin specific polyclonal and monoclonal antibodies to capture and detect aflatoxins. Primary (polyclonal) antibodies for aflatoxin B1 were covalently attached to 2.8 μm-diameter magnetic beads using a bi-functional cross linking agent. A secondary antibody for aflatoxin B1 was also covalently linked to DNA oligonucleotides based on the luciferase gene as a reporter DNA molecule. Real-time PCR amplification of the reporter DNA after aflatoxin capture provides for sensitive detection of toxin, if present. Magnetic beads were coupled to primary antibodies while secondary antibodies were coupled to DNA reporter molecules. Amplification (PCR) targeting an internal portion of the reporter molecule gave DNA fragments of the expected size. Coating of magnetic beads with capture antibodies has been facilitated by use of the BeadRetrieverTM. Quantification of toxins in food and feed samples will involve signal amplification strategies using real-time PCR amplification of reporter DNA using specific primers. This methodology is rapid, sensitive, and will help to detect and quantify low levels of aflatoxins that could otherwise be fed to food production animals, domestic animals (cats, dogs, horses), or humans through aflatoxin-contaminated cereal grains and feed.

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