Sauders B.D.,Cornell University |
Sauders B.D.,Food Laboratory Division |
Overdevest J.,Cornell University |
Fortes E.,Cornell University |
And 5 more authors.
Applied and Environmental Microbiology | Year: 2012
A total of 442 Listeria isolates, including 234 Listeria seeligeri, 80 L. monocytogenes, 74 L. welshimeri, 50 L. innocua, and 4 L. marthii isolates, were obtained from 1,805 soil, water, and other environmental samples collected over 2 years from four urban areas and four areas representing natural environments. Listeria spp. showed similar prevalences in samples from natural (23.4%) and urban (22.3%) environments. While L. seeligeri and L. welshimeri were significantly associated with natural environments (P < 0.0001), L. innocua and L. monocytogenes were significantly associated with urban environments (P < 0.0001). Sequencing of sigB for all isolates revealed 67 allelic types with a higher level of allelic diversity among isolates from urban environments. Some Listeria spp. and sigB allelic types showed significant associations with specific urban and natural areas. Nearest-neighbor analyses also showed that certain Listeria spp. and sigB allelic types were spatially clustered within both natural and urban environments, and there was evidence that these species and allelic types persisted over time in specific areas. Our data show that members of the genus Listeria not only are common in urban and natural environments but also show species- and subtype-specific associations with different environments and areas. This indicates that Listeria species and subtypes within these species may show distinct ecological preferences, which suggests (i) that molecular source-tracking approaches can be developed for Listeria and (ii) that detection of some Listeria species may not be a good indicator for L. monocytogenes. © 2012, American Society for Microbiology.
Block E.,University at Albany |
Cody R.B.,JEOL United States Inc. |
Dane A.J.,JEOL United States Inc. |
Sheridan R.,Food Laboratory Division |
And 2 more authors.
Pure and Applied Chemistry | Year: 2010
Three different instrumental methods have been used to examine the organosulfur chemistry of intact and cut garlic and onions: X-ray fluorescence spectroscopic imaging (XFS), direct analysis in real time (DART) mass spectrometry, and ultra-performance liquid chromatography-(Ag +)-coordination ion spray mass spectrometry (UPLC-(Ag +)CIS-MS). The first technique has been used to map the location of different chemical forms of sulfur in intact and damaged onion cells, the second technique, to identify the reactive, volatile sulfur compounds formed on cutting the plants, and the third technique, to identify members of families of polysulfides found in the distilled oil of garlic. © 2010 IUPAC.
Wang K.,University at Albany |
Groom M.,ECOspray Ltd |
Sheridan R.,Food Laboratory Division |
Zhang S.,University at Albany |
Block E.,University at Albany
Journal of Sulfur Chemistry | Year: 2013
Diallyl disulfide reacts within minutes with liquid sulfur at 120°C giving a family of diallyl polysulfanes, All2S n (n=3-22), characterized by ultra-performance liquid chromatography-(Ag+)-coordination ion spray-mass spectrometry (UPLC-(Ag+)CIS-MS). Similarly, garlic oil (GO), bis-(2-methyl-2-propenyl), bis-(2-chloro-2-propenyl), bis-(3-methyl-2- butenyl), and bis-(2-cyclohexen-1-yl) disulfides all give families of polysulfanes with up to 22 sequential sulfur atoms. New members of families of silver chelators with up to 10 sulfur atoms were found in GO using UPLC-(Ag +)CIS-MS. © 2013 Copyright Taylor and Francis Group, LLC.© 2013 Copyright Taylor and Francis Group, LLC.
Latorre A.A.,Cornell University |
Pradhan A.K.,Cornell University |
Pradhan A.K.,University of Maryland University College |
Van Kessel J.A.S.,U.S. Department of Agriculture |
And 6 more authors.
Journal of Food Protection | Year: 2011
The objectives of this study were to estimate the risk of illness for raw milk consumers due to Listeria monocytogenes in raw milk sold by permitted dealers, and the risk for people on farms who consume raw milk. Three scenarios were evaluated for raw milk sold by dealers: raw milk purchased directly from bulk tanks, from on-farm stores, and from retail. To assess the effect of mandatory testing of raw milk by regulatory agencies, the number of listeriosis cases per year was compared where no raw milk testing was done, only a screening test to issue a permit was conducted, and routine testing was conducted and milk was recalled if it was L. monocytogenes positive. The median number of listeriosis cases associated with consumption of raw milk from bulk tanks, farm stores, and retail for an intermediate-age population was 6.6 × 10 -7, 3.8 × 10 -5, and 5.1 × 10 -5 cases per year, respectively. In populations with high susceptibility, the estimated median number of cases per year was 2.7 × 10 -7 (perinatal, i.e., pregnant women and their fetuses or newborns) and 1.4 × 10 -6 (elderly) for milk purchased from bulk tanks, 1.5 × 10 -5 (perinatal) and 7.8 × 10 -5 (elderly) for milk from farm stores, and 2.1 × 10 -5 (perinatal) and 1.0 × 10 -4 (elderly) for milk from retail. For raw milk consumed on farms, the median number of listeriosis cases was 1.4 × 10 -7 cases per year. A greater risk of listeriosis was associated with consumption of raw milk obtained from retail and farm stores as compared with milk obtained from bulk tanks. This was likely due to additional time-temperature combination steps in the retail and farm store models, which increased the chances for growth of L. monocytogenes in raw milk. A close relationship between prevalence of L. monocytogenes in raw milk and the values of disease incidence was observed. Hence, a reduction in the number of cases per year in all populations was observed when a raw milk-testing program was in place, especially when routine testing and recalling of milk was conducted. © International Association for Food Protection.
Sheridan R.S.,Food Laboratory Division |
Kemnah J.L.,Food Laboratory Division
Journal of Chromatographic Science | Year: 2010
The glycoalkaloid content of pet food containing potatoes is investigated using a liquid-liquid solvent extraction followed by analysis by ultra-high pressure liquid chromatography tandem mass spectrometry (UPLC-MS-MS). Pet food samples are homogenized and extracted with a solution of 50:50 (v/v) acetonitrile-deionized water containing 5% acetic acid. Following vortexing and centrifugation, 3 mL of the supernatant is filtered and diluted in deionized water. The extract is injected onto a reverse phase C18 UPLC column with an initial mobile phase composed of 0.15% acetic acid in water (A) and 0.15% acetic acid in methanol (B) in a ratio of 70:30, respectively. The mobile phase reaches a final concentration of 15% A and 85% B over 10 min, at which point it is returned to the initial conditions. α-Solanine is measured by monitoring transitions m/z = 868.50 → 398.40 and 868.50 → 722.50, while α-chaconine is measure by monitoring transitions m/z = 852.60 → 97.80 and 852.60 → 706.50. Each analyte is measured and combined to determine total glycoalkaloid content (TGA). The results of the analysis of 52 pet food samples indicate both glycoalkaloids are present in all samples and two pet foods were found to contain > 100 μg/g total glycoalkaloid.