Lethality of heat to Escherichia coli 0157:H7: D-value and Z-value determinations in ground beef

D-values and z-values were determined for lean (2.0% fat) and fatty (30.5% fat) ground beef inoculated with approximately 10(7) Escherichia coli 0157:H7 cells per g. Inoculated ground meat was sealed in glass thermal death time tubes which were completely immersed in a circulating water bath and hel...

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Bibliographic Details
Published in:Journal of food protection 1991-10, Vol.54 (10), p.762-766
Main Authors: Line, J.E. (ABC Research Corporation, Gainesville, FL), Fain, A.R. Jr, Moran, A.B, Martin, L.M, Lechowich, R.V, Carosella, J.M, Brown, W.L
Format: Article
Language:English
Subjects:
Biological and medical sciences
CALOR
CARNE DE RES
CHALEUR
COMPOSICION DE LA CANAL
COMPOSITION DE LA CARCASSE
CORPS GRAS
ESCHERICHIA
Food industries
Food microbiology
Fundamental and applied biological sciences. Psychology
GRASAS
RESISTANCE A LA TEMPERATURE
RESISTENCIA A LA TEMPERATURA
TECHNIQUE DE CULTURE
TECNICAS DE CULTIVO
TEMPERATURA
TEMPERATURE
TRAITEMENT THERMIQUE
TRATAMIENTO TERMICO
VIANDE BOVINE
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Summary:D-values and z-values were determined for lean (2.0% fat) and fatty (30.5% fat) ground beef inoculated with approximately 10(7) Escherichia coli 0157:H7 cells per g. Inoculated ground meat was sealed in glass thermal death time tubes which were completely immersed in a circulating water bath and held at prescribed temperatures for predetermined lengths of time. Survival was determined by enumeration on plate count agar (PCA) containing 1% sodium pyruvate and by the 2-h indole test of Lee and McClain (7). D-values for fatty ground beef exceeded those for lean ground beef at the temperatures tested. D-values for lean and fatty ground beef at 125 degrees F were 78.2 and 115.5 min, respectively, as enumerated on PCA plus pyruvate. D-values at 135 degrees F were 4.1 and 5.3 min for lean and fatty beef. At 145 degrees F D-values were determined to be 0.3 and 0.5 min. D-values calculated from 2-h indole test data for lean and fatty ground beef at 125 degrees F were 80.1 and 121.0 min, respectively. D-values at 135 degrees F were 4.0 and 7.4 min for lean and fatty beef and at 145 degrees F a D-value of 0.2 min was calculated for lean beef only, due to insufficient survival of E. coli 0157:H7 in fatty beef at this temperature. The z-values determined for lean beef and fatty beef using PCA were 8.3 and 8.4 degrees F respectively. The z-value for lean beef using the 2-h indole data was 7.8 degrees F. No z-value for fatty beef using 2-h indole data could be determined
ISSN:0362-028X
1944-9097
DOI:10.4315/0362-028X-54.10.762