Food

I am aware that heating chicken to higher temperatures in the fryer will make it safe- my entire point was please make it hotter. I’ve continued this because, when I asked why 58 degrees was being used, the response was concise and succinct; 58 degrees is safe. In your original post, you talk about ‘cooking’ the chicken in the sous vide, then ‘bringing it up to temperature’ in the fryer- a process that apparently only takes a minute, as the chicken is already cooked.

So I followed the link posted. It led to a report (here http://www.fsis.usda.gov/wps/wcm/connect/9ab2e062-7ac8-49b7-aea1-f070048a113a/RTE_Poultry_Tables.pdf?MOD=AJPERES), based on a scientific study designed to clarify at what times and temperatures are required to destroy salmonella, in order to clarify an earlier report by the USDA. There are, of course, tables at the bottom that show that chicken is Salmonella free after being held at 28 minutes at 58 degrees. So yes, two hours in a water bath should be fine. And, in all honesty, I can’t find anything else about salmonella contrary to this. And yet the USDA does not say, anywhere that I can find, that chicken is safe to eat after being cooked like this- just that it’s free from salmonella. What they actually recommend is a blanket number of 73.9 C. Which clearly does not consider sous vide cooking, so is not satisfactory here. But I did find this- http://www.fda.gov/downloads/Food/GuidanceRegulation/RetailFoodProtection/FoodCode/UCM374510.pdf - this is the US Food and Drug Administrations current food preparation guidelines, based on up to date information, and includes a sous vide section, on page 99- it says that whilst whole joints of meat including beef, but not chicken, are considered safe when held at 58C for 18 minutes (and various other times/temps), chicken must be cooked to 63 C for three minutes, or 74 for 15 seconds. Again, why the difference?

This is one of the appendices from the fsis scientific study- http://www.fsis.usda.gov/wps/wcm/connect/212e40b3-b59d-43aa-882e-e5431ea7035f/95033F-a.pdf?MOD=AJPERES. It says that “heating deviations, which most often involve slow come-up time or an inordinate dwell time within the optimum temperature range for microorganism growth, can foster the multiplication of many pathogens. This multiplication sometimes can be so prodigious that even recooking may be ineffective in rendering the product safe. Also, certain toxigenic bacteria can release toxins into the product. Some of these toxins, such as those of Staphylococcus aureus, are extremely heat stable and are not inactivated by normal recooking temperatures.” (page three).

In a study on the heat resistance of Staphylococcus aureus- “With S. aureus 198E, heat injury could be demonstrated only when large numbers of cells (10(8)/g) were present and at a product temperature of 140 degrees F (60 degrees C). On tryptic soy agar and tryptic soy agar plus 7% NaCl media, at temperatures less than 140 degrees F, the counts were virtually identical; above 140 degrees F, the counts converged, with the organisms dying so rapidly that heat injury was not demonstrable.” That’s from the summary, there’s more detail in the article, esp. P.742- they say explicitly that below 59C there’s little to no evidence of injury or killing. But above 62 C, the bacteria died so rapidly they couldn’t record it.
The study is from the seventies, and the line between death and not seems to be a bit more linear now in relation to temperature, but more recent studies show it’s heat resistance capabilities- it can take twenty minutes to kill it at sixty degrees, see here- http://www.foodstandards.gov.au/publications/.../Staphylococcus%20aureus.pdf and http://www.foodstandards.gov.au/publications/Documents/Staphylococcus%20aureus.pdf. If the chicken is being heated in a water bath from fridge temperatures, you could be pretty close to the line here, by the time it’s come up to temperature. You will probably also have Campylobacter and clostridium botulinium present in chicken which operate similarly- they start to denature at 50, with peak deaths varying between 57 and 63C. See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1352264/ and http://edis.ifas.ufl.edu/fs104 . Both of them produce toxins that can and have killed.

Of course, that paragraph isn’t the strongest. One of the studies is old, the other two are vague about this circumstance. I’m not really able to evaluate it any further- I’m not a scientist, I’m not able to- but I did find this, which I think is interesting: https://www.food.gov.uk/strategicevidenceprogramme/x02projlist/fs246004dfs102028- it’s a report from 2012 by the food standards agency on the safety of sous vide cooking, with the aim of creating a simple ‘model’, where people can input product, and get given time and temp. On page 7 of the report, they say that there is insufficient data between 40 and 60 degrees on the responses of different bacteria- there seems to be a grey patch between reproducing and dying, and they need more research.

And that, I think, is my opinion after looking up all that lot. I think the information in the original link by Mr Sworld is over-simplistic, and unreliable. On the other hand I’m not going to pretend that I’ve ‘proven’ it dangerous. I think it’s a risk, and would personally avoid.