Hey

Question

Can anyone help me out with this problem. For part a i understand i plot microbial numbers against time on semi log paper to determine D value for the two temperatures. But i'm unsure how to do part b.
Alicyclobacillus acidoterrestris is a quite hat resistant microorganism that has been causing problems in the fruit juice industry.Data below shows the thermal inactivation data determined experimentally for A. acidoterrestris spores in orange juice at 85.2�‹ and 91�‹C.

85.2 degrees celcius
Time Spore concentration
(min) in the juice N (cfu/ml)

0 min 1.9* 10^7
20 min 1.6* 10^7
40 min 9.1* 10^6
60 min 7.9* 1^0^6
80 min 4.8* 10^6
120 min 6.2* 10^5
160 min 8.9*10^4
180 min 5.5*10^4

91 degrees celcius
time (min) Spore concentration
in the juice N (cfu/ml)
0 min 1.7*10^7
2 min 8.1*10^6
5 min 4.0*10^6
8 min 2.6*10^6
11 min 1.8*10^6
14 min 8.0*10^5
16 min 5.9*10^5
18 min 2.6*10^5
21 min 2.8*10^5
a. Determine thermal resistance parameters of Alicyclobacillus acidoterrestris in the orange juice.
b. Suggest an appropriate P91�‹C�]value for this juice.

Thanks