Question

Let, for instance, 15 second s at 71.7 C be the applied treatment to a milk sample (a zation process approved by FDA and one of the legally specified pasteurization processes in the UK). Assume that it is contaminated with L. Monocytogenes at the level of one cell in 50ml. Without knowing the heat-resistance parameter (D value) ot the actual strain, we must make the 'worst case' assumption and use the highest heat resistance data reported in literature (a) Freely-suspended cells: D(71.7)- 3.3 seconds (b) Intra-cellular Lisferia: D(71.7) 4.1 seconds If the contamination level is 1 in 50ml or 20 per liter (Ng) what the expected rate of survival?

Answer 1

Decimal reduction value is the time in seconds for sterilization to reduce the population of microorganism to one decimal ​​​​​​​

t = time a heat treatmeut 15 Sec No - Tnitial number t micro 0ngaidms in salutior 2009/ter 4-1 2econds toY listena al .7C D: D X No D X -Dx Nt = t Dx NO D x Nt- anti ey No DV D 1.3 4. auth ly2.35) O004 1-e 4out o 1600 wi be tlu suwial ate