Rust and Pathogens: Quality Control Risk in Food Industry

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In summary: Rust films are porous and can absorb moisture, so could conceivably become breeding grounds for bacteria. On the other hand, a cast iron pot with a little rust which develops if the pot is washed in water (usually with soap), dried in the dish rack, and then stored...it probably won't cause any problems.In summary, rusty metal is a potential pathogen risk, but it is not always harmful.
  • #1
wolram
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Working in the food industry and quality control people can not tell me why rusty metal is all ways put down as a pathogen risk, what is this risk please.

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  • #2
The biggest risk that comes to mind; rusty metal is known to harbour Tetanus bacteria*, so if you should cut your skin on a piece of "rusty metal", it is a good idea to check your tetanus immunization and if needed, get a booster shot. If there was rusty metal in my food, I would be concerned about it tearing some skin on its journey to my stomach. :bugeye:*tetanus bacterium: Clostridium tetani, anaerobic bacillus, produces the neurotoxin tetanospasmin. Thanks ian for catching my oversight on category of microorganism.
 
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  • #3
Ouabache said:
Tetanus virus

Tetanus is a toxin produce by a bacterium not a virus. Being a microbiologist, the difference is important.

For rusting iron, it probably has to do with iron availability for bacteria and other pathogen. Virtually all bacteria requires iron and they need to get it from somewhere. One way to limit bacterial grow, which reduces pathogen/spoilage risk, is to remove or reduce accessibility to freely available iron. Human do that with transferin, lactoferrin and haem. Changes in iron availability will greatly impact how a pathogen grow, so rusting iron might increase the amount of freely available iron in the environment and bacteria would grow much faster. This is, however, speculation on my part.
 
  • #4
Thanks guys, i should have said that there is zero possibility of this rust getting into any food product, it seems to be iansmiths suggestion that rust is a possible feeding area,that is the cause.
 
  • #5
Another reason is simply the challenge of disinfecting something as porous as rusted metal since there are lots of nooks and crannies for the bacteria to hide in away from the disinfectants you're cleaning it with. Sand it down and give it a coat of paint and folks are happy that it's again a non-porous surface that can be properly disinfected.
 
  • #6
Moonbear said:
Another reason is simply the challenge of disinfecting something as porous as rusted metal since there are lots of nooks and crannies for the bacteria to hide in away from the disinfectants you're cleaning it with. Sand it down and give it a coat of paint and folks are happy that it's again a non-porous surface that can be properly disinfected.
Yes, but I've never heard of any other common warning about tetanus except rust.

I've always wondered what the connection was. Now I know.
 
  • #7
DaveC426913 said:
Yes, but I've never heard of any other common warning about tetanus except rust.

Actually, it's any deep puncture wound. The rust in those cases usually implies a dirty surface...something old, lying around a long time. You'd want a tetanus booster if you got any sort of deep puncture wound, such as an animal bite, not just the proverbial rusty nail. It's an anaerobic bacteria, so can thrive deep in those wounds.
 
  • #8
wolram said:
Thanks guys, i should have said that there is zero possibility of this rust getting into any food product, it seems to be iansmiths suggestion that rust is a possible feeding area,that is the cause.

I believe that would be Micobially Induced Corrosion (MIC) as well. A bacterial colony's biofilm and associated exudations can cause the underlying metal to corrode. It could even be galvanic corrosion from differential aeration due to the overlying biofilm.
 
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  • #9
chemisttree said:
I believe that would be Micobially Induced Corrosion (MIC) as well. A bacterial colony's biofilm and associated exudations can cause the underlying metal to corrode. It could even be galvanic corrosion from differential aeration due to the overlying biofilm.

Thanks all, i guess i should not moan about the cost of constantly replacing rusty hardwear.
MoonB, painting parts is frowned upon, we can get away with it in extreme cases.
 
  • #10
On the other hand, food exposed to rusty (oxidized) metal, may not necessarily, be harmful (ref: scientist's opinion) . I've tasted a metallic flavor when I cooked chili in a cast-iron dutch oven (lesson: don't cook anything acidic in cast-iron), and also in breads or cake baked in a pan with small amount of oxidation on its surface.
 
  • #11
You'd just have to label it all iron-fortified! :biggrin: (Though, it would defeat the purpose if it's calcium-fortified too.)
 
  • #12
Rusty iron or steel is usually associated with a moist and dirty environment, hence the concern that rust would also mean bacterial contaminiation. Certainly a rusty nail on the ground or in a rotten piece of wood outdoors would likely have bacteria such as Clostridium tetani resident.

Rust films are porous and can absorb moisture, so could conceivably become breeding grounds for bacteria. On the other hand, a cast iron pot with a little rust which develops if the pot is washed in water (usually with soap), dried in the dish rack, and then stored in a clean, dry cabinet would likely not have bacteria in the rust. Nevertheless, wash it or even heat it before use.

As Ouabache indicated, it might change the taste of the food.

Interesting, MIC can occur in certain stainless steels, which have an increased sulfur content. These are usually anaerobic bacteria however.
 
  • #13
Iron oxides can affect food colors, as well as taste.
 
  • #14
The title of this thread is an attention getter. What is the first thing that comes to mind, when you see "rust and pathogen" in the same phrase?

The ubiquitous rust diseases of course. If, by chance you want to take a closer look at some rusts, there is an extensive http://www.btny.purdue.edu/Herbaria/Arthur/ [Broken] at Purdue Univ, with 100,000 rust specimens (the largest collection of Uredinales in the world). I recall a fellow there, who made regular trips to South America (early 1980s) to collect specimens in the wild, before many areas of plant (and fungal) diversity were destroyed.
 
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  • #15
Ouabache said:
The title of this thread is an attention getter. What is the first thing that comes to mind, when you see "rust and pathogen" in the same phrase?

The ubiquitous rust diseases of course. If, by chance you want to take a closer look at some rusts, there is an extensive http://www.btny.purdue.edu/Herbaria/Arthur/ [Broken] at Purdue Univ, with 100,000 rust specimens (the largest collection of Uredinales in the world). I recall a fellow there, who made regular trips to South America (early 1980s) to collect specimens in the wild, before many areas of plant (and fungal) diversity were destroyed.

I think only a mycologist, or maybe plant scientist, would think of that first. :biggrin: Most of us think rusty nail and tetanus.
 
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1. What are the most common pathogens found in foods?

The most common pathogens found in foods include Salmonella, E.coli, Listeria, and Campylobacter. These bacteria can cause foodborne illnesses and can be found in a variety of foods such as raw meat, eggs, and produce.

2. How can rust increase the risk of food contamination?

Rust is a common problem in the food industry as it can create an ideal environment for pathogens to grow and thrive. Rust can also contaminate food directly if it flakes off from equipment or surfaces and can act as a nutrient source for bacteria.

3. What steps can be taken to prevent rust and reduce the risk of food contamination?

Regular maintenance and inspection of equipment and surfaces can help prevent rust from forming. It is also important to clean and sanitize equipment properly to remove any rust or bacteria present. Using stainless steel or other rust-resistant materials can also help reduce the risk of contamination.

4. How does quality control play a role in preventing food contamination?

Quality control measures, such as regular testing and monitoring, can help identify and address potential sources of contamination in the food industry. This can include checking for rust on equipment and surfaces, as well as testing for the presence of pathogens in food products.

5. What are the potential consequences of food contamination from rust and pathogens?

The consequences of food contamination can range from mild illness to severe health complications, and in some cases, even death. In addition to the impact on human health, food contamination can also have severe financial and reputational consequences for food companies.

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