fish cooking
Leon Aristizabal
Sølve Huse
I was thinking the salting of the fish is a preserving technique in the first place.... to prevent bacteria growth?
In Joan Rocas book “sous vide” i presents a recipe that suggest 55 degrees for cooking desalted bacalao. Would he suggest this if it wasn´t safe?
Mainly half of that book is about food safety.
S
On 11-10-07 14:49, "Leon Aristizabal" <lari...@gmail.com> wrote:
James...@fabi.up.ac.za
in food preservation. It won't necessarily prevent bacteria from growing, it'll
just dry out the meat. Bacteria usually need quite a bit of moisture to grow
and survive, so they might be present on the meat, but not necessarily at a
high enough number to cause a safety risk.
Leon Aristizabal
Jack
Its a little more complex than that since safe holding temperatures are not absolute but have a time component,
See http://www.hi-tm.com/Documents2001/time-temp-calculations.html CALCULATING THE TOTAL GROWTH OF BACTERIA IN COOKED FOOD USING THE FDA CODE CONTROLS by O. Peter Snyder, Jr., Ph.D Hospitality Institute of Technology and Management)
He says
“The US FDA Food Code, is, a simplification and scientifically wrong because pathogen growth actually starts at about 29.3ºF and stops, for all practical purposes, at 125ºF. The speed of growth depends on the temperature. The FDA codes appear to be based on a maximum of a 10x generations (doubling) of pathogens such as Listeria onocytogenes at 41ºF and Salmonella / Staphylococcus aureus at 115ºF. Based on this we can extrapolate to other temperatures,”
Similarly we can calculate safe cooking times as a function of temperature (adapted from http://www.cfsan.fda.gov/~dms/fc01-3.html#3-4 )
Jack Lang
Cambridge UK
James...@fabi.up.ac.za
growth of bacteria (I won't say microorganisms because microorganisms are
more than just the bacteria in this case; there's also fungi, algae, viruses,
etc.) is not just about how much water there is or the temperature or the
time, it's all of these. Think about a person; they need warmth, water, and
food to stay alive. Bacteria are similar.
Thinking about your problem, it makes sense to put the bowl of water with
the fish in it into the refrigerator. Typical internal temperature for a fridge is
4ºC. Basic physics says that water is less likely to change it's temperature
as much as atmospheric temperature (hence it's use in car radiators, etc.)
so the water is likely to remain at 4ºC even if the fridge door is opened
several times a day. So after four days temperature of the water should be
4ºC, assuming that that is the temperature your fridge is set at 4ºC.
Jorge Ruiz
There is the called "hurdle effect". That is, all potential hurdles
preventing microbial growth (water activity, temperature, pH and so on)
work together (water activity os a measurement of the amount of free water
for microorganism, it is nearly 1 in raw fish or meat, in which all most
of the water is available, and it is lower when the product has been
dehydrated and/or salted, because salt makes the water not available for
microorganisms). I think there is no problem with desalting cod at 4ºC for
4 days. In fact, only a very few poisoning bacteria can grow below 4ºC,
and not at the water activity of salted cod. The problem is that most home
fridges do not reach 4ºC (mine is frequently at 7ºC...).
The other problem is to cook at (let's say) 50ºC. At this temperature most
bacteria survive (or even their growth is enhanced). However, given that
the time that the fish is kept at this temperature is not long, and that
the fish is immediately consumed after cooking (at least, this is the
recommended procedure), the microbial risk is not that high (from my point
of view, more or less the same as with raw fish). Well, another day we can
talk about another risk with this way of cooking: Anisakis.
By the way, I know the book from Roca quite well. Despite their efforts in
considering food safety, it's much better to go directly to a food safety
book to check these items.
Cheers
--
Jorge Ruiz Carrascal
Tecnología de Alimentos
Facultad de Veterinaria UEx
Campus Universitario s/n
10071 Cáceres
SPAIN
personal webpage: http://higiene.unex.es/weborges/orges.html
blog: http://www.lamargaritaseagita.com/index.php/weblog/C3/
Tfn.: +34 927 257123
Fax: +34 927 257110
Nathan Myhrvold
Food safety is a complicated topic – one result is that any simple rule you are told is probably wrong.
Jack is correct in what he says below. Holding time depends on temperature. Soaking salt cod in cold water in a refrigerator is safe – probably about as safe as holding fresh fish (i.e. a couple days).
Fish can be eaten raw (sushi) if it is fresh and clean. Once you start to cook with heat, the amount is up to you. Nearly any internal temperature for cooking fish will not sufficient to sterilize it and kill all bacteria, but if the time is short this is fine. Most food is consumed without being sterilized (salad!). As Jorge said in another email, so long as the time involved between cold storage, and consumption is short enough, this is OK.
So, the temperature for salt cod is up to you – it depends on what effect you want. At different temperatures (and times) you get different texture.
You can’t give a temperature / time combination without knowing what end result you want, and ultimately this is personal preference. Many traditional recipes for fish overcook it (by my taste at least). This is particularly true for traditional salt cod recipes. But sometimes people are accustomed to the traditional texture, so they object if it is lower.
I prefer most cold water fish at 45C internal temperature. Salmon is generally best at 40C, and escolar or tuna at 38C.
Nathan
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Ed Charles
<Temp-danger-zone-Big.gif>
Jorge Ruiz
There are different bacteria groups. Some may grow in absence of oxygen
(moreover, they need absence of oxygen: they are the so called anaerobic
bacteria). In fact, Clostridium botulinum or Clostridium perfringens (both
anaerobic)are among the potential risk in sous-vide products, because they
are anaerobic bacteria and can resist quite high temperatures.
Some other bacteria can grow with or without oxygen (facultative
anaerobic; for example E. Coli O157). So, absence of oxygen is great for
avoiding Salmonella and aeobic microorganisms, but not for others.
Cheers
Sølve Huse
Makes me almost think I'm lucky for having survived so far. ;-)
As for the end result versus time/temp combination it makes sense for me to
use a higher internal temperature. With fresh fish I would definitely go for
a much lower internal temp, but bacalao is though and rubbery in its raw
state (even when desalted for 4 days), and my experience is that it actually
softens and gets more moist when it reaches internal temp of 65 degrees
Celsius.
Sølve
Jack
Fortunately Clostridium spp are destroyed in a mildly acid environment, so
add some lemon juice or even white wine to the cooking medium.
Fish has little connective tissue so the cooking time is really just for the
temperature to stabilise; there is no point in extended cooking times unlike
in meat where it assists the collagen to convert and dissolve.
I guess it depends how you intend to further process or serve the salt
cod.Othen the texture will be changed, for example in a fishcake.
It is said the Portuguese have over 1000 recipes for Bacalhau, and certainly
more than one for each day of the year.
Personally, I am very fond of a truffled brandade.
Jack Lang
Jorge Ruiz
You should not give this kind of advises. It is true that Cl. botulinum
does not grow below 4.6 pH, but you need quite an amount of lemon to reach
this pH. In addition, there are studies in which at an even lower pH,
Clostridium botulinum could grow in meat and soy, probably due to a
protective effect of proteins.
As far as connective tissue in fish is concerned, it is not only that the
amount is much lower than in meat (there are many different fish, of
course), but a question of a different type of collagen (it becomes
solubilized at a lower temeprature) and of a different structure:
connective tissue in meat surrounds every single muscle fibre, every
bundle of fibres, and every muscle, while in fish it is mainly
constituting the septa (myosepta) that separate the muscles (myotomes).
Cheers
--
Jorge Ruiz Carrascal
Tecnología de Alimentos/Food Science
Facultad de Veterinaria UEx
Campus Universitario s/n
10071 Cáceres
SPAIN
personal webpage: http://higiene.unex.es/weborges/orges.html
blog: http://www.lamargaritaseagita.com/
Tfn.: +34 927 257123
Fax: +34 927 257110
Robert CAUCHI
Judd Howie
Hi all!
Greetings from sunny Sydney!
It’s great to see the list up and running again, some excellent and informative discussion.
I’m a chef and (now) chef recruiter for roles around the globe and am in contact with several hundred chefs a month. Not only is this discussion list very helpful and interesting to me, but it would also be for the professionals I communicate with on a daily basis.
Would the list have any objections to me linking it in my next newsletter at all?
Our September 07 Chef Newsletter has just gone online here.
Please check www.hostec.com.au/chefjobs often for our latest available chef roles worldwide.
Kind regards,
Judd
Howie
Executive Consultant - Culinary
Sydney
: +61 2 80020222 London: +44 20 81146105
New York:
+1 917 2101223
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Regards
Robert CAUCHI
John Placko
I'm ok with it as well.
John Placko
Corporate Chef
Campbell Company of Canada
"Extraordinary, Authentic Nourishment for All"
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Fax: 416 253-8659
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Judd Howie
I just think the type of discussions happening here are so beneficial to chefs around the world that are wanting to learn a little more re MG in general.
Your average (or even above average) chef these days is only dipping his toe in the water when it comes to this area of food, would be great to bring the movement into the main stream a little further as it is very much mainly supported by research chefs, food scientists and the extremely self motivated/interested at the moment.
Our September 07 Chef Newsletter has just gone online here.
Please check www.hostec.com.au/chefjobs often for our latest available chef roles worldwide.
Kind regards,
Judd
Howie
Executive Consultant - Culinary
Sydney
: +61 2 80020222 London: +44 20 81146105
New York:
+1 917 2101223
Hong Kong: +852 36786736 Singapore:
+65 66226400
Level 7 263 Clarence
Street Sydney NSW
Australia 2000
CONFIDENTIAL
This email & any attachments are confidential and may contain copyright
material of Hostec or third parties. If you are not the intended recipient of
this email you should not read, distribute, copy, print, store or act in
reliance on this email or any of its attachments. The email is intended for the
use of the individual to which it is addressed & may contain information
that is privileged and confidential. If you have received this email in error,
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from your system. Hostec respects your privacy. Our privacy policy can be
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From: molecular-...@googlegroups.com [mailto:molecular-...@googlegroups.com] On Behalf Of John Placko
Sent: Saturday, October 13, 2007 12:59
AM
To: molecular-...@googlegroups.com
Leon Aristizabal
Marc Nicholas
-marc
Jack
link to the list, and help spread the word.
AT the moment the list is open.
However any spam or off topic messages resulting from a wider audience will
be dealt with severely.
Best
Jack
John Placko
----- Original Message -----
From: "Jack" [Ja...@lang.net]
Sent: 10/12/2007 06:06 PM CET
To: <molecular-...@googlegroups.com>
Subject: [MG] Re: The list
Best
Jack
Andrea Ossola
Hi Everybody,
I have been trying to do "airs" "Clouds" and "shaving Cream" with lecithin, xantan & metilcellulose somehow as soon there is some sugar in the liquid yield less than a sugar-free liquid.
As any of you faced the same or do you want to share your recipe? ......I have tried to sweeten with spelda and assugrin and it works but I have a problem how those product taste...
I was looking as well for Cuisson Sous Vide material, especially the Dangerous part of this cooking technique if done improperly... all about toxin, bacteria formation etc....
Thanks & have a terrific day
Andrea