Question

# What is the dead temperature for killing anaerobic bacteria?

What is the dead temperature for killing anaerobic bacteria?

### Topics

0 / 0  ·  23 Answers  ·  6239 Views

• Sarwar Khan · Bogor Agricultural University
it is depend on the type of the bacteria itself..
example of anaerobic bacterias are E. coli and Staphylococcus aureus which are facultative anaerobic or Colostridium botulinum which is obligate anaerobic..
They are mesophilic bacterias which has around 48 degree centigrade of maximum temperature for their growth..
Most of the pathogenic bacterias are belong to the mesohilic group, but there are also some which are thermophilic which has around 60 degree centigrade of maximum growth temperature. Therefore, heat treatment which is widely known as "pasteurization" is often considered as the easiest and applicable yet effective method to reduce microbiolocial contamination in raw foods.
The temperature used is around 63 - 65 degree centigrade (30 minutes) for or 73 - 75 degree centigrade(15 seconds). But it can also be increased up to 90 degree for some minutes (called high pasteurization) depend on the initial number of contamination or other purposes such as manufacturing the food into the fermented products.
• Ihab Habib · Alexandria University
Dear Magdy,

This depend on a property called the decimal reduction time or D-value, which is different from an organism to another and sterilisation (killing) times are based on this. The D value is also specific to a temperature. Therefore when quoting D-values for an organism, the temperature must also be quoted, usually as a subscript to the "D".
e.g. For Clostridium botulinum (the anaerobic most serious one from public health point of view), D121 = 0.2 min.

The most usual decimal reduction is a "12D" reduction i.e. N0/N = 10^12 and log N0/N =12. The sterilisation (killing) time is often referred to as the "F number". F is the product of the D-value and the decimal reduction. Thus, for a 12D reduction, F = 12 DT. Because C. botulinum is the basis of most food sterilisations, the F value is determined on the basis of a reference temperature of 121° C. In such cases, F is usually designated F0.
e.g. For a 12 D reduction of clostridium botulinum, F0 = 12 x 0.2 = 2.4 min.

Hope you did not get lost, but it is all about the D and the F values.
Yours
Ihab
• Eugenie Baril · Université de Bretagne Occidentale
exactly right.
"Dead temperature" does not mean anything. Please precise the time of treatment, objectives of the treatment, environment of treatment and of post-treatment.
• François Bourdichon · Barry Callebaut
Dear Magdy,

when considering heat treatment as a bactericidal process, one should consider vegetative cells or sporulated form, aerobic or anaerobic growth potential being of poor relevance.

Apart from sterilization, the heat treatment to be applied depends of the micro-organism of concern, as specified earlier the D value (germ and matrix specific, time needed for a log reduction) and the z value.

ICMSF provides clear explanation on the topic, you can also see information from dairy associations as in following url:
http://www.pir.sa.gov.au/__data/assets/pdf_file/0005/60485/ANZDAC_HeatTreatment_June07_2_2.pdf

If you have access to journal of applied microbiology, I can suggest you following publication concerning heat treatment of spores:
http://www.ncbi.nlm.nih.gov/pubmed?term=16907801

Please go through relevant chapter of following book for more insights on heat treatment:

Best
François
• Biao Suo · Henan Agriculture University
Dear Magdy,

It is really difficult to say what is a killing temperature for a certain of foodborne pathogen. It depends on the condition what the bacteria is, the food or matrix where it exists. There already some online prediction curve you can refer to, such as ComBase, PMP, etc. I hope this could be helpful for you.

Best wishes

Biao Suo
• Dave Roeser · Garden Fresh Farms, Inc
It depends on the aerobic bacteria , but most should die off around 150 degrees Fahrenheit. Unless it is a thermophilic bacteria and then it would be upwards of 200 degrees.
Garden Fresh Farms
• Not only temperature but process involved could be determinate in the destruction of bacteria. Such as irradiation. When solar cooking the thermal component is infrared heat conversion although some ultraviolet must also be transmitted as food products processed in this manner have a particularly long shelf life. Also pasteurization techniques that hold foods at lower temps for longer periods are also effective. Thus solar cooking is beneficial for safety in processing food and purifying water. A sustainable resource that could improve longevity of product and have other applications with sterilization properties.
• Hedayat Hosseini · Shahid Beheshti University of Medical Sciences
Thermal killing of bacteria defines as a time/temperature combination,so we are not able to determine a time for killing bacteria without consideration of time.In addition the phase bacteria growth, pH, composition of the medium,oxidation/reduction potential of medium and other similar factors are important.
• Dear Magdy
The thermal killing rate of organism depend on:1., species and type of organismes 2., enviroment and type of processing treatment that mean cold or hot treatment, 3. produce endospore or not 4., extrathermophile or not
• Ina Ramírez · Universidad Nacional Autónoma de México
Magdy,
All the answers are right, you have to consider, kind of bacteria, intrinsic factors (nutrients, growth factors and inhibitors in food, water activity, pH, redox potential), extrinsic factors and the microbial stress response in the food environment (stress adaptation and sublethalstress and injury).
• Chidi Ezeama · Michael Okpara University of Agriculture, Umudike
Dear Magdy,
You did not provide any background information to your question.However, thermal killing is the preferred method as it will achieve your purpose. In addition you must consider other factors as earlier noted by my colleages.
• Jackie Picard · James Cook University
This is great information. I always look at what are the most possible resistant bacteria that would be present i.e. in milk, they would be Coxiella burnetii and from there work out would would be the temperature required to kill these bacteria. Since heat can affect the properties of some foods either changing the taste, appearance or nutritional quality, it is also important to evaluate all the means available i.e. irradiation (gamma, UV), wet and dry heat or chemical, and decide which ones are the most optimum (food quality, cost, practical application). In food safety, all the work has actually been done for us and all we have to do is consult published standards. Countries that are very interested in food safety i.e. members of the EU tend to have very comprehensive lists.
• Jyoti Khade · Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola
Bacteria love temperatures that revolve around the temperature of our body (36.6º C, 98.6º F). Holding products at higher temperatures (greater than 130º F, 54º C) restricts the growth of bacteria. Increasing temperatures over 60º C (140º F) will start killing them. Most bacteria need oxygen (aerobic), others thrive without it (anaerobic). All of them hate cold, and around 32º F, (0º C) they become lethargic and dormant when the temperature drops lower. Keeping them at low temperatures does not kill them, but only stops them from multiplying. Once when the conditions are favorable again, they will wake up and start growing again.
• Anwar Saad · Quality & Confirmity Council CTL Abu Dhabi UAE
D- values is critical is the time required to destroy 95% of the organisms) and thermal death (TDT) (the time necessary to kill a given number of organisms at a specified temperature) and depend on the organism status (vegetative cells need less temperature than spore former bacteria.
• Enric Riera · Polytechnic University of Catalonia
U.S. F.D.A. published some time ago a report on microbial inactivation. It was a very comprehensive work, including classical thermal technologies as well as new inactivation technologies, as high presure, ohmic heating, etc.
You can find the part on traditional heating processes in:
http://www.fda.gov/Food/ScienceResearch/ResearchAreas/SafePracticesforFoodProcesses/ucm100198.htm
I think it can be a good place to look for the data you need
• Doyle Pat · University College Dublin
Question What is the prevalence of pathogens in raw milk and can such pathogens be ranked in order of severity from a food safety perspective !!
• Piyawan Gasaluck · Suranaree University of Technology
I think Professor Mohamamed and Ina Ramirez answers are cover the factors should be considered. Your information does not specify the product your are interested in. It would be clear if you know that process first.
• François Bourdichon · Barry Callebaut
Pathogens in raw milk depends also which type of raw milk (goat, buffalo, cow, camel) you are referring to.

"Classicaly", pathogens found in raw milk are Campylobacter, Listeria, Salmonella and E.coli STEC.
S. aureus can also be an issue if milkimg practices are anot adequate, in a lesser extent B. cereus for the same reason.

For ranking in order of severity, refer to scientific litterature:
http://www.ncbi.nlm.nih.gov/pubmed/15992306
http://online.liebertpub.com/doi/pdf/10.1089/fpd.2005.2.115
• Jackie Picard · James Cook University
The pathogens that are potentially in raw milk is dependent on the disease status of the animal, farm, country and region. One of the more serious zoonoses are Brucella abortus (cows) and B. melitensis (nanny goats) and possibly Mycobacterium bovis as they cause systemic disease, which if untreated can have serious consequences. However, many countries have eradicated these diseases. Coxiella burnettii the agent of Q-fever is extremely hardy and although most people that are infected remain healthy, a few can become really ill. All these agents as well as the ones listed by Francois are found in the milk of apparently healthy cows, sheep and camels. Horse milk has the potential to contain the ones mentioned by Francois. In countries that have to consider brucellosis, it is important to note that milk souring and cheese preservation methods may be insufficient to destroy the bacteria. Heat treatment is by far the most successful method.
• Marco Campus · Agenzia della Regione Sardegna per la ricerca scientifica
From a practical point of view, if you want to achieve the so called "commecial sterility" you have to destroy 12 Log cycles of C. Botulinum. In thermal treatments, this goal is achieved treating the canned food in a retort at 121 °C operating temperature for 15 min. You have to consider the contribution of come up temperature and cooling temperature above near 65 °C to the general effect integrating the so called "heat penetration curve", in order to perform a process that preserve as much as possible the nutritional characteristics , avoiding overheating. The commercial sterility concept applies also to alternative preservation tecniques.
• Anderson Soares · Federal University of Minas Gerais