Lethality of Heat to Escherichia coli 0157:H7: D-Value and Z-Value Determinations in Ground Beef
- 1 October 1991
- journal article
- Published by Elsevier in Journal of Food Protection
- Vol. 54 (10) , 762-766
- https://doi.org/10.4315/0362-028x-54.10.762
Abstract
D-values and z-values were determined for lean (2.0% fat) and fatty (30.5% fat) ground beef inoculated with approximately 107 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°F were 78.2 and 115.5 min, respectively, as enumerated on PCA plus pyruvate. D-values at 135°F were 4.1 and 5.3 min for lean and fatty beef. At 145°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°F were 80.1 and 121.0 min, respectively. D-values at 135°F were 4.0 and 7.4 min for lean...Keywords
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