@article{schuman_sheldon_2003, title={Inhibition of Listeria monocytogenes in pH-adjusted pasteurized liquid whole egg}, volume={66}, ISSN={["0362-028X"]}, DOI={10.4315/0362-028X-66.6.999}, abstractNote={Although the transmission of L. monocytogenes to humans via pasteurized egg products has not been documented, L. monocytogenes and other Listeria species have been isolated from commercially broken raw liquid whole egg (LWE) in both the United States and Ireland. Recent Listeria thermal inactivation studies indicate that conventional minimal egg pasteurization processes would effect only a 2.1- to 2.7-order-of-magnitude inactivation of L. monocytogenes in LWE; thus, the margin of safety provided by conventional pasteurization processes is substantially smaller for L. monocytogenes than for Salmonella species (a 9-order-of-magnitude process). The objective of this study was to evaluate the inhibitory effects of nisin on the survival and growth of L. monocytogenes in refrigerated and pH-adjusted (pH 6.6 versus pH 7.5) ultrapasteurized LWE and in a liquid model system. The addition of nisin (1,000 IU/ml) to pH-adjusted ultrapasteurized LWE reduced L. monocytogenes populations by 1.6 to > 3.3 log CFU/ml and delayed (pH 7.5) or prevented (pH 6.6) the growth of the pathogen for 8 to 12 weeks at 4 and 10 degrees C. Bioactive nisin was detected in LWE at both pH values for 12 weeks at 4 degrees C. In subsequent experiments, Listeria reductions of > 3.0 log CFU/ml were achieved within 24 h in both LWE and broth plus nisin (500 IU/ml) at pH 6.6 but not at pH 7.5, and antilisterial activity was enhanced when nisin was added as a solution rather than in dry form.}, number={6}, journal={JOURNAL OF FOOD PROTECTION}, author={Schuman, JD and Sheldon, BW}, year={2003}, month={Jun}, pages={999–1006} }
 @article{schuman_sheldon_vandepopuliere_ball_1997, title={Immersion heat treatments for inactivation of Salmonella enteritidis with intact eggs}, volume={83}, ISSN={["1364-5072"]}, DOI={10.1046/j.1365-2672.1997.00253.x}, abstractNote={The effects of water‐bath immersion heat treatments on the inactivation of Salmonellaenteritidis within intact shell eggs were evaluated. Six pooled strains of Salm. enteritidis (ca 3×108 cfu, inoculated near the centre of the yolk) were completelyinactivated within 50–57·5 min at a bath temperature of 58°C and within 65–75min at 57°C (an 8·4 to 8·5‐D process per egg). Following the initial 24 to35‐min come‐up period, semilogarithmic survivor curves obtained at 58 and 57°C yieldedapparent decimal reduction times (D‐values) of 4·5 and 6·0 min, respectively.Haugh unit values increased during heating, while yolk index and albumen pH values wereunaffected. Albumen clarity and functionality were affected by the thermal treatments; therefore,extended whip times would be required for meringue preparation using immersion‐heated eggwhites. Immersion‐heated shell eggs could provide Salmonella‐free ingredients for thepreparation of a variety of minimally‐cooked foods of interest to consumers and foodserviceoperators.}, number={4}, journal={JOURNAL OF APPLIED MICROBIOLOGY}, author={Schuman, JD and Sheldon, BW and Vandepopuliere, JM and Ball, HR}, year={1997}, month={Oct}, pages={438–444} }
 @article{schuman_sheldon_foegeding_1997, title={Thermal resistance of Aeromonas hydrophila in liquid whole egg}, volume={60}, ISSN={["0362-028X"]}, DOI={10.4315/0362-028X-60.3.231}, abstractNote={Aeromonas hydrophila (AH) is a psychrotrophic spoilage bacterium and potential pathogen which has been isolated from a variety of refrigerated foods of animal origin, including raw milk, red meat, poultry, and commercially broken raw liquid whole egg (LWE). Decimal reduction times (D values) of 4 strains of AH (1 egg isolate, 2 egg processing plant isolates, 1 ATCC type strain) were determined in LWE using an immersed sealed capillary tube (ISCT) procedure. Initial populations (7.0 to 8.3 log CFU/tube in 0.05 ml LWE) were heated at 48, 51, 54, 57, and 60°C, and survivors were plated onto starch ampicillin agar (48 h at 28°C). D values ranged from 3.62 to 9.43 min (at 48°C) to 0.026 to 0.040 min (at 60°C). Both processing plant isolates were more heat resistant than the ATCC strain. Decimal reduction time curves (r2 ≤ 0.98) yielded ZD values of 5.02 to 5.59°C, similar to those for other non-spore-forming bacteria. D values of the most heat resistant AH strain were also determined in LWE at 48, 51, and 54°C using a conventional capped test tube procedure (10 ml/tube). Cells heated in test tubes yielded nonlinear (tailing) survivor curves and larger (P ≤ 0.05) apparent D values at each temperature than those obtained using the ISCT method. This study provides the first thermal resistance data for AH in LWE and the first evidence that straight-line semilogarithmic thermal inactivation kinetics may be demonstrated for Aeromonas using the ISCT procedure.}, number={3}, journal={JOURNAL OF FOOD PROTECTION}, author={Schuman, JD and Sheldon, BW and Foegeding, PM}, year={1997}, month={Mar}, pages={231–236} }
 @article{schuman_sheldon_1997, title={Thermal resistance of Salmonella spp. and Listeria monocytogenes in liquid egg yolk and egg white}, volume={60}, ISSN={["0362-028X"]}, DOI={10.4315/0362-028X-60.6.634}, abstractNote={Decimal reduction times (D values) were determined for Salmonella spp. and Listeria monocytogenes (five pooled strains per pathogen) in raw liquid egg yolk (pH 6.3) and liquid egg white (pH 8.2 versus 9.1) by using a low-volume (0.05 ml per sample) immersed sealed-glass capillary-tube procedure. For Salmonella , D values ranged from 0.087 min (at 62.2°C) to 0.28 min (at 60°C) in yolk. and from 1.00 min (at 58.3°C) to 7.99 min (at 55.1° C) in egg white (pH 8.2). For Listeria , D values ranged from 0.58 min (at 62.2°C) to 1.34 min (at 60°C) in yolk, and from 2.41 min (at 58.3°C) to 7.59 min (at 55. 1°C) in egg white (pH 9.1). Mean ZD values for Salmonella ranged from 3.54 to 4.33°C; for Listeria , ZD values ranged from 6.06 to 9.43°C. In egg white, the heat sensitivity of both pathogens was enhanced at pH 9.1, although this trend was more evident for Salmonella spp. than for L. monocytogenes over the temperature range tested. The results indicate that USDA-prescribed minimal pasteurization requirements for liquid egg yolk (equivalent to 3.9- to 22.1-D processes, on the basis of the present study) would be far more lethal to the Salmonella and L. monocytogenes strains tested than would the corresponding thermal processes for liquid egg white (equivalent to 0.7- to 2.2-D processes).}, number={6}, journal={JOURNAL OF FOOD PROTECTION}, author={Schuman, JD and Sheldon, BW}, year={1997}, month={Jun}, pages={634–638} }