lectures must know

Question 1

ph optimum of microbes

• bacteria
• yeast
• filamentous fungi
• lactic/acetic acid bacteria

Answer 1

• bacteria : 6-8 neutral
• yeast : 4,5-6 more acidic
• filamentous fungi: 3,5-4 even more acidic
• lactic/acetic acid bacteria: 5-6 also acidic

Question 2

what does mesophilic mean

and list 3 mesophilic bacteria

Answer 2

normal temp - human and animal temp
37 is optimum
clostridium, salmonella enterica, staphylococcus

Question 3

what does thermophle mean

list 3 bac

Answer 3

likes the hot
45-80 is optimum
camphylobacter, clostridium thermosaccharolyticum, bacillus stearothermophilus

Question 4

what does psychrophile mean

and what undergroups

Answer 4

likes the cold
obligate psychrophile
facultative psychrophile - aka psycrotrophic that loves cold and warm

Question 5

Z value definition

Answer 5

the change in temperature wich results in a tenfold change in the decimal reduction time (D) or thermal death time (TDT)
(using higher temp - require less time)
(using lower temp - more time)

Question 6

F value definition

Answer 6

12D - Thermal death time (TDT) at 121,2C
describes a microorganism
C.botulinum F is 2,52 min at 121,1 degrees

Question 7

F0 value

Answer 7

F0= the nessecary time for the destruction of clostridium botulinum by isothermal heat treatment at 121,1C
F0 is used to compare different heat treatment
F0 describes the technology
heat treatment have many stages ( heating, holding, cooling - cumulative effect)

Question 8

which two bacteria are most heat resistent in milk

Answer 8

coxiella burnetti

mycobacterium paratuberculosis

Question 9

at what temperature is UHT and ESL milk heat treated

Answer 9

ESL 100-134 for 0,1 sec??

UHT 135-140 - comercially sterile