Concerns about possible transmission to people drinking unpasteurized milk are being talked about a lot. Apparently they fed mice unpasteurized milk, and they got the virus, but it seems like the temperature required to kill. The virus is higher than what they used to sterilize the milk. How is this safe?
In: Biology
Can’t speak to avian flu specifically, but in general killing pathogens depends on a combination of temperature and time, not just temperature. So probably the answer in this case is that 165F would kill off avian flu much quicker than 145F, but pasteurization holds the milk at 145F for long enough to do the job.
Almost all anti-bacterial temperatures are given as the temperature needed to kill *instantly*
If the pasteurization lasts any longer than one microsecond it can still kill the same thing at lower temperatures with more time
I don’t know specifically for milk, but a lot of food safety is not just the temperature but how long it’s held there. For example chicken is safe right away at 165, but it’s also safe at 155 for (I believe) eight minutes. It’s likely the milk is better if it doesn’t hit the higher temperature, and since the virus can’t survive the lower temperature for long they can just hit that lower temperature and wait the virus out
Heat sanitization is always heat x time. From what I’m seeing standard pasteurization procedure is 145 for at least 30m, or 162 for 15 seconds.
I’m also not seeing any studies that says the avian flu is actually able to survive up to 165, everything I’m seeing shows it being killed in the 130 – 158 range depending on length of exposure. 158+ does the job in a minute.
I’m assuming you got that number from some cooking recommendations? I mean to put it simply they tend to be incredibly conservative to account for the fact that home cooks are usually completely garbage at taking measurements. If they say 145 for 30 minutes then that’s going to be picked up by the average consumer as “130 on my totally miscalibrated 30 year old thermometers is probably good enough” so they always state the highest possible worst case numbers.
Killing microorganisms by heating them is a function of two things: time and temperature.
If you heat a liquid to a higher temperature, it needs to be sustained at that higher temperature for less time in order to have the same lethality when compared to the liquid being heated to a lower temperature.
So basically: a microorganism can potentially be viable during excursions up to 165° F, but if you heat it to a lower temperature for longer then that will kill it. Milk being pasteurized at 145° F is going to have that temperature held for potentially over half an hour which will kill basically everything. If they were to heat it up to 165° F they would not need to hold it at that temperature for as long, but the higher temperatures affect other things like taste and consistency which is why lower temperatures are used.
As far as I understand what’s been found in milk is viral genetic material not viable viral particles. The viral genetic material could just be the remnants of damaged viral particles
Commercial milk is normally pasteurized at 165 for 15 seconds. The milk you get in the cooler is High temp shot time pasteurized (HTST). It’s not normal pasteurization which is 145 for 30 minutes.
The FDA doesn’t tell you this because most people are just stupid and will get it wrong, but you can cook food at lower temps for a longer time to make it safe.
Chicken is recommended to be cooked to 165°, but if you cook it to 145° and hold it at that internal temp for 9 minutes, it’s completely safe to eat.
Avian flu begins to break down at 83’F, it can survive for 1 day at this temperature. At 134’F avian flu can survive for about 30minutes. Milk is pasteurized at about 150’F for 30 minutes which would kill most harmful microorganisms.
I found a document that referenced 165’F to kill avian flu inside a fowl carcass. It specified 165’F internal temperature and “no pink.” To reach an internal temperature of 165’F the external temperature has to be over 200’F, I suspect avian flu dies within seconds at 165’F and eating pink bird meat is bad for humans.
So the pasteurization process is safe because it kills avian flu, not instantly but quick enough, and 165’F is for cooking an actual bird, inside not outside.
Because 165 is the instant kill temp
The reason for listing an instant kill temp is similar to the reason why they don’t bear proof garbage cans and stuff in national parks, because humans are really really dumb sometimes and the amount of overlap between smart bears and dumb humans makes it pointless to bear proof garbages because then it would also be dumb human proof
So since theirs a significant amount of humans that would not understand the idea of cook times and such to kill bacteria at lower temps it’s better to go with the one that doesn’t need an ELI5 and just say 165 kills it that was their dumb ones don’t give themselves avian flu… well don’t give themselves it as easily
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