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Simon

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Posted 15 July 2009 - 07:15 AM

I know very little about the various Bacteria, Viruses, Parasites and Toxins that can be found in food and cause illness. I thought it might be an idea for a thread dedicated to the little beasts where the more knowledgeable members can tell us:

- What the various Bacteria, Viruses, Parasites and Toxins are
- Where they can be found
- What foods they especially like to contaminate
- What problems or illnesses they can cause people
- How to get rid of them / cure the sick
- Their danger level as rated against other bugs
- How to prevent them from contaminating food in the first place

Maybe if a member told us all about one type in particular or maybe if there were enough interest we could set up a dedicated thread for each nasty. Maybe we could have a specific forum on microbiology?

What do you think?

Regards,
Simon


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Posted 15 July 2009 - 08:45 AM

great idea simon.. so we can more focus on micro.. And I think you can add how to analysis micro especially in food and beverage product..



Simon

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Posted 15 July 2009 - 11:41 AM

I added the new food microbiology forum. This thread is in it now. Feel free to start any new topics on the subject of food microbiology and use it how you wish.

Maybe someone can answer a part of my initial question. :smile:

Regards,
Simon


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Posted 16 July 2009 - 10:13 PM

It was my Nephews tenth Birthday today so we called round and had a nice barbecue; I asked for some Coleman’s English mustard for my steak sandwich. It duly arrived, I spread some on and ate up. A few minutes later my Father in Law said, “sheesh I’m not having any of that mustard it has an expiry date of July 2004”. Imagine my surprise. After that I examined the mustard and it did smell a bit strange. It didn’t say “use by” or “best before” or “expiry” on the label it just had a date on it.

The ingredients are... Water, Mustard Flour, Sugar, Salt, Wheat Flour, Spice, Citric Acid.

Should I expect to get ill?

Regards,
Simon



Not knowing how much of a hypochondriac you are Simon, I thought I'd wait a while before posting.

My brother was ill last year from eating mustard that had been left in the fridge for a while after opening.

We concluded it was more than likely caused by mycotoxins produced by moulds. Moulds are capable of growing at low temperatures and pH. The onset of food poisoning was fairly rapid which is typical of toxins. Once a jar is open it is quite easy for it to be contaminated. I think squeezy bottles are probably a better option.

Even better option buy new at a greater frequency i.e. less than every 5 years!

Regards,

Tony



:thumbup:

Good point Tony, haven´t thought about the possibility of the presence of toxins before you even start your production process for mustard.

Simon, grate idea to have this forum, I would like to see here the experience of forum members related to their real life problems, rather than text from books (also very good information if somebody can post a book).

Regards,

FSSM


Simon

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Posted 22 July 2009 - 08:58 PM

:thumbup:

Good point Tony, haven´t thought about the possibility of the presence of toxins before you even start your production process for mustard.

Simon, grate idea to have this forum, I would like to see here the experience of forum members related to their real life problems, rather than text from books (also very good information if somebody can post a book).

Regards,

FSSM

Well let's hope it's used by members FSSM. I though it was worth a go.

Regards,
Simon

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Posted 02 August 2009 - 06:57 PM

Good point Tony, haven´t thought about the possibility of the presence of toxins before you even start your production process for mustard.


Thank you but I meant the Mustard was contaminated with moulds after opening and then produced the mycotoxins.

Regards,

Tony :smile:


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Posted 02 August 2009 - 07:07 PM

I added the new food microbiology forum. This thread is in it now. Feel free to start any new topics on the subject of food microbiology and use it how you wish.

Maybe someone can answer a part of my initial question. :smile:

Regards,
Simon



Hi Simon et al

Check out www.fsai.ie - go to resources and publications then factsheets - all you need to know about common pathogens - if only I knew how to add a link!!

Rosie


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Posted 04 August 2009 - 04:36 PM

I know very little about the various Bacteria, Viruses, Parasites and Toxins that can be found in food and cause illness. I thought it might be an idea for a thread dedicated to the little beasts where the more knowledgeable members can tell us:

- What the various Bacteria, Viruses, Parasites and Toxins are
- Where they can be found
- What foods they especially like to contaminate
- What problems or illnesses they can cause people
- How to get rid of them / cure the sick
- Their danger level as rated against other bugs
- How to prevent them from contaminating food in the first place

Maybe if a member told us all about one type in particular or maybe if there were enough interest we could set up a dedicated thread for each nasty. Maybe we could have a specific forum on microbiology?

What do you think?

Regards,
Simon



OHHH interesting question Simon!

I'm sure there are others here who are better informed than i am, but fortunately i do know a little bit more than the micro basics.

Different products (and industries) are concerned with different bacteria or viruses.

If your in canning the pathogen of choice would be Clostridium botulinum. As those in the canning sector would vouch, it's a nasty little bugger!

Those dealing with milk powders or chocolate would probably come out in a cold sweat because of Salmonella. Mind you, as Edwina Curry was quick to point out, eggs can also be affected.

The meat industry probably worries more about good old Campylobacter, although again Salmonella and E Coli could but the fear of god (or allah) into you!

Bacillus cereus is another player. Usually associated with reheating chinese rice. This one forms a spores in the rice which are heat resistant and the spores can produce a toxin.

We come to E Coli, probably one of the more publicised bacteria., especially E Coli 0157 which there has been a few outbreaks from in the past few years, where there have also been deaths. For a while Scotland was E Coli capital of the UK (outbreak wise) but i fear that Wales is taking over this mantle, with 2 cases currently from a chip shop in North Wales. It can grow in many foods, not really having a preference, but it is an indicator of faecal contamination.

Listeria monocytogenes frightens the majority of us involved in the chilled sector. Can survive (and reproduce) at cold temperatures. It can be found in soil, which is why we tend to be a bit fussy about footwear!

There are a number of viruses. Probably the one we all hear about is Rotaviruses (or cruise ship sickness). Those involved in cultured products such as cheeses or yogurts are probably more concerned about phages!

Then we come to our fungi...good old yeasts and moulds. Some of these can produce spores, but they are deemed to be spoilage organisms rather than pathogens. There are hundreds of different types, far too many to mention, but some do have benefits too. Blue cheeses etc

Hope that has whetted your appetite, so to speak.

If somebody else wants to add, be interested to see.

Caz x


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Posted 04 August 2009 - 08:15 PM

Very good idea! I am not that much into microbiology but I think its cool. Here is some small contribution...

Psychrotrophic microorganisms


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Definition

There is a confusion between the definition of microorganisms that grow at low temperature. Psychrophilic microorganisms are those that have an optimal temperature of growth at 15 C, a maximum temperature < 20 C and a minimum temperature < 0 C. Microorganisms that can multiply at 0 C, but with a different optimal and maximum temperature from psychorphilic, are defined as psychrotrophic.

Hint: psychrophilic and psychrotrophic are both Greek words. Now I hate doing this (like people who claim that everything is Greek... I am DEFINATELY NOT one of them) but I think its nice to explain where those "flashy", weird names come from especially for those who are not familiar with the Greek language.

Psychrophilic (ψυχρόφιλα in Greek) comes from the words ψυχρό = Psychro = cold and φίλος = philos = friend. So psychrophilic microorganisms would be those who are "friends of cold".

Psychrotrophic (ψυχρότροφα in Greek) comes from the word psychro and τροφή = trofi = food. So psychrotrophic microorganisms are those that are "eating cold" ... uhh... kinda... well you get the point! ...or not? :P

Major temperatures for microorganism growth
Group / min / optimal / max
Themophilic / 40-45 / 55-75 / 60-90
Mesophilic / 5-15 / 30 -45 / 35-47
Psychrophilic / -5 to 5 / 12-15 / 15-20
Psychrotrophic / -5 to 5 / 25-30 / 30-35


Most psychrophilic microorganisms are sensitive at temperatures higher than 10 C and for this reason they are not considered as important as psychrotrophic. Psychrotrophic bacteria seem to grow better in medium temperatures and thus are considered as a subgroup of mesophilic who are able to grow under the minimum growth temperature of mesophilic.

- Psychrotrophic bacteria are included in many species such as:
Aeromonas, Alcaligenes, Arthrobacter, Bacillus, Chromobacterium, Citrobacter, Clostridium, Corynobacterium, Enterobacter, Erwinia, Escherichia, Flavobacterium, Klebsiella, Lactobacillus, Leuconostoc, Microbacterium, Micrococcus, Moraxella, Proteus, Pseudomonas, Streptomyces, Streptococcus, Vibrio, Yersinia, Listeria.

- Psychrotrophic yeasts include the species:
Candida, Torulopsis, Cryptococcus and Rhodotorula.

- Psychrotrophic moulds include:
Penicillium, Cladosporium, Trichothecium, Aspergillus, Geotrichum, Botrytis.

Many psychrotrophic microorganisms, when in large numbers, can cause food spoilage such as off-flavours and texture modification. Their rate of growth depends on temperature and thus the shelf life of the product that is maintained in a low temperature depends also on that temperature.

The counting of psychrotrophic microbes of foods that are going to be preserved at low temperature (0 to 10 C) is important because their presence (especially in large numbers) is an indication of a potential spoilage during their preservation time.

Psychrotrophic microorganisms cannot grow at -17 to -20 C. But if foods that are maintained at the above temperatures, melt during their preservation at refrigerator temperatures (e.g. at supermarkets), then psychrotrophic microbes can multiply and spoil the products. Some species can grow at a slow pace even at -5 to -12 C. Quality loss from microbial action at products that are maintained at such low temperatures can be observed after long periods of preservation.

Methods
For the counting of psychrotrophic microbes the Petri method is usually followed. As substrates can be used solid non-eclectic substrates (e.g. standard methods agar, trypticase soy agar...) or eclectic ones (e.g. crystal violet tetrazolium agar or C.V.T.). The cultures are held at 7 C for 10 days. The temperature and the duration values are arbitrary. They can be changed so that they can adapt/simulate the actual preservation conditions of the food product. In the case of spread plate method the petri dishes with the substrate are cooled at 7 C. For the counting of Gram negative bacteria, C.V.T. eclectic substrate is used. In that case, and generally when eclectic substrates are used, the cultures are held at 30 C for 48 hours or at 22 C for 5 days.

Quality test
Psychrotrophic microbes are counted a) in a speciment of fresh product and b) in a speciment taken after the preservation of the product at low temperatures for 5-7 days. The cultures are held at 30 C for 48 hours or at 22 C for 5 days. Those two counts can inform us for the ability of growth of the psychrotrophic microbes of the food product.

Explaining the results
The presense of a large number of psychrotrophic microbes in foodstuff that are preserved at low temperature (dairy products, meat, poultry and fish products) means the multiplication of the initial microbial count and the mass contamination, before or during the preservation of the product. From the number and the kind of microorganisms one can understand if the product is some stage of spoilage. Usually if the number of bacteria is higher than 10^7-10^8 the products show some kind of deformity/spoilage.

The above are taken from the booklet notes (from Dr. Deligaris Nikolaos) that I was given while studing at my university. They are kinda old... but I hope they can prove to be useful...

Something more to read...

Psychrotrophic microorganisms

Psychrotrophic microorganisms

Psychrotrophic bacteria in foods - disease and spoilage

Chill storage




Cheers!
Filip

Edited by SaRaRa, 04 August 2009 - 09:05 PM.


Simon

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Posted 04 August 2009 - 08:47 PM

I'm going on a diet. Err...maybe not. Great information anyway. Thanks, I think we can build a useful reference here for both consumers and foodies.

Regards,
Simon


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