Temperature / time rate for cl. botulinum spores hatching
This is a very specific question. I have been a time and I still am looking for an answer or rather an argument.
This question is in line with thermal sterilization and also in line with somethig SaRaRa posted last july 2009:
THERMAL STERILIZATION OF SOME PRODUCTS:
FOOD / Fo (time required for the total destuction of microorganisms in minutes)
Beans / 7-15 min
Spinach / 4-5 min
Tomato / 0,7-1 min
Corn / 9-15 min
Mushroom / 6-10 min
Meat / 6-8 min
Fish / 2,5-8 min
Chicken / 6-8 min
Condensed milk / 5-6 min
As SaRaRa said, these times are related to a temperature of 121ºC.
If I am not wrong, the main concern in vegetables cans is clostridium botulinum spores. It is said that the minimun treatment to produce a safe product ( vegetable can )is that that reach a Fo=3 as minimun. That is to say, by applying Fo=3 we can say that all cl. botulinum spores are destroyed to an safe level.
I suggest the following: if I get all the cl. botulinum spores to be hatched before entering the thermal sterilization then I can conclude that I will need a lower temperature to kill all the c. botulinum vegetative forms. This is why I am very very interesting in knowing the temperature/rate need for cl. botulinum spores hatching.
This question arose after being in a vegetable can industry. There is a product whose process can not reach a temperature higher than 110ºC otherwise the product would be the same.
The company has been doing this product for years; they have a product library and analysis from the final product been done after the use by date. The life time is two years. Everything is OK, seems like they are doing it well but we need to find an argument or explanation.
Any opinion, link or advice will be of great help.
Thank you very much in advance
Bet regards
Esther
Hi Ester,
Even if the equipments are not capable of reaching beyond 110 C, it is still possible to destroy the spores, by extending the holding time.
But your method might work too. Searched on the Wikipedia and found the Tyndallization method:
Tyndallization is an old process for sterilizing food. It is still occasionally used.
A simple, effective, modern sterilizing method is to heat the substance being sterilized to 121°C for 15 minutes in a pressure cooker; see autoclave. If a pressure cooker is unavailable and sterilization proceeds instead using unpressurized heating to 100°C in boiling water, the heat will kill the bacterial cells but the viability of bacterial spores may survive. In this latter case the Tyndallization process can be used to destroy the spores. The process is named after its inventor, the 19th century scientist John Tyndall. Tyndallization essentially consists of boiling the substance for 15 minutes for three days in a row. On the second day most of the spores that survived the first day will have germinated into bacterial cells. These cells will be killed by the second day's heating. The third day kills bacterial cells from late-germinating spores. During the waiting periods over the three days, the substance being sterilized is kept at a warm room temperature; i.e., a temperature that is conducive to germination of the spores. Germination also requires a moist environment. When the environment is conducive to the formation of cells from spores, the formation of spores from cells does not occur. The Tyndallization process is generally effective, but its reliability is not considered 100% certified. It is not often used today, but it has applications in sterilizing some things that cannot withstand pressurized heating, such as gardener's seeds. It is not necessary to bring the temperature all the way up to 100°C to kill bacterial cells.
I found the following links with a quick search. I think what you are looking for is in the first link (there are loads of tables and charts, you 'll see).
Clostridium Botulinum (microbiological specifications)
Factors affecting germination, outgrowth and sporulation
Factors affecting germination, growth, sporulation and toxin production
Control (of Cl Botulinum)
Probability statements for C. Botulinum thermal inactivation... and more (Predictive Modelling)
Ecology of C. Botulinum - Growth
Good luck!
Philip
I am going to read all your links and I will be back to you.
One thing, the problem is not that the equipment is not able to reach temperatures higher than 110ºC, the problem is that by doing so the product will significally change.
If I not wrong, regardless how long you can extend the holdng time you will needd a mnimun temeprature from safety point of view. By reading some articles I did conclude that the minimun temperature for cl. botulinum spores is 110ºC. Is this figure familiar to you?
On the other hand, I need a firm argument for the next certification audit.
Best regards
Esther
The heat treatment given to a low acid canned food (having
a pH higher than 4.2) sufficient to inactivate 1012 spores of
Clostridium botulinum. This heat treatment is called the Fo value
and it is equivalent to a process of 3 mins at 121ºC, 10 mins at
115ºC or 32 mins at 110ºC.
CCFRA run a 5 day course on the principles of canning which is excellent.
Caz x
Could you share the product which requires 110°c. In my experience it could be green peas which could get smashed and become paste like.
Regards,
Sujit
This question arose after being in a vegetable can industry. There is a product whose process can not reach a temperature higher than 110ºC otherwise the product would be the same.
The company has been doing this product for years; they have a product library and analysis from the final product been done after the use by date. The life time is two years. Everything is OK, seems like they are doing it well but we need to find an argument or explanation.
Bet regards
Esther
I would expect them to have a comprehensive validation study that has challenged the process and found it to be effective.
Regards,
Tony