Do you sometimes think "Why do I keep paying insurance premiums for my car, boat, house, personal liability, camera etc? I hardly ever make a claim". In all the years I have been paying premiums, I have only once made a claim on my car insurance, and that was when one of the local semi-evolved simians stole it and drove it into a ditch. Would you consider not insuring your house? Would you be able to continue with business as usual if your offices burned down? The chances of making a claim and getting some of the premiums back are quite small.
The probable reason we continue to pay is that it gives us peace of mind, knowing that if we do smash the car into a BMW or Rolls Royce, we won't be bankrupted by the repair bills for the other car. We can drive, secure in the knowledge that we have that one covered.
Pasteurisation of milk is insurance and free. A mild heat treatment kills all the pathogens that might have got into the milk during milking and transport, leaving the nutritional value essentially unchanged. Why would you even consider drinking raw milk or eating raw cheese, knowing that there is a small chance that it could result in illness that would change your life or that of your family for ever? There has been plenty written about the dangers of Escherichia coli O157:H7 and other STECs, so I'm not going to go over it again here. (See other posts on E. coli by clicking the E. coli label at the RHS of this blog).
Please, this Christmas season, if you really want to eat and drink raw milk products, you can make an informed choice. But don't give these products to children - they don't have that choice and a dose of E. coli O157:H7 can lead to HUS, which will probably ruin the rest of their lives.
Friday, December 17, 2010
Thursday, December 16, 2010
Microbial tongue twisters
Today Bill Marler published a link to a clip of Larry King making an ass of himself while introducing a segment on Escherichia coli.
Perhaps it's a good thing he used the abbreviation E. coli
That set me thinking. Does the general public find the names of bacteria so difficult to pronounce that they put all thoughts of them to the back of their minds? Or do they regard all bacteria as "germs"?
The difficulty is that there are literally thousands of different bacteria, so microbiologists have to give them names that mean something and so that they can be grouped for study. Sometimes the genus is named after its discoverer, or in honour of a famous microbiologist. Salmonella was named after D.E. Salmon, an American bacteriologist; Bacillus is named from the Latin noun meaning "a small rod", while Acetobacter is so named because it oxydises ethanol to acetic acid (vinegar).
When microbiology students start out, they often have difficulty in remembering, or even pronouncing, names like Vibrio parahaemolyticus and Pediococcus pentosaceus. Small wonder that the rest of the population has problems.
In fact, in terms of food poisoning, Joe Sixpack doesn't need to know these names. Basically, if you mistreat food by contaminating it, or by holding it at temperatures that permit growth, there is a possibility that numbers of pathogenic bacteria will increase to what is termed an "infecting dose" or that toxins will be secreted into the food. The latter cause food poisoning when ingested. So what is our favourite bloke going to do to keep himself and his family safe?
Easy - clean, cook, cover and chill. This little mnemonic includes it all: Clean-handle all foods with clean hands and utensils; Cook frozen foods after proper defrosting and use a thermometer to ensure that poultry or meat patties are properly heated through. If foods are to be reheated, ensure that the temperature reaches at least 75C right through to the centre; Cover cooked foods during cooling and place in the refrigerator within 30 minutes; Chill foods to 4C and hold at that temperature until served (remember that some bacteria grow readily at refrigerator temperatures, so even chilled food will not remain safe forever) or hold above 60C. You can find more extensive guidelines for these important concepts on the MAF website in New Zealand, or the FDA sites in America.
In the Southern Hemisphere, we are at the start of the barbecuing season. It's important to be really careful - never put cooked meat on the same plate as raw meat and pre-cook chicken legs etc. making sure that patties are heated right through.
I was once at a company barbecue, standing in line to collect my meal. I heard someone behind me whisper "See what he takes, he's a microbiologist". I didn't need to name the bacteria that might have survived on my meats, choosing only steak and thoroughly cooked burger patties.
http://www.youtube.com/watch?v=omaF9kA94Io&NR=1
Perhaps it's a good thing he used the abbreviation E. coli
That set me thinking. Does the general public find the names of bacteria so difficult to pronounce that they put all thoughts of them to the back of their minds? Or do they regard all bacteria as "germs"?
The difficulty is that there are literally thousands of different bacteria, so microbiologists have to give them names that mean something and so that they can be grouped for study. Sometimes the genus is named after its discoverer, or in honour of a famous microbiologist. Salmonella was named after D.E. Salmon, an American bacteriologist; Bacillus is named from the Latin noun meaning "a small rod", while Acetobacter is so named because it oxydises ethanol to acetic acid (vinegar).
When microbiology students start out, they often have difficulty in remembering, or even pronouncing, names like Vibrio parahaemolyticus and Pediococcus pentosaceus. Small wonder that the rest of the population has problems.
In fact, in terms of food poisoning, Joe Sixpack doesn't need to know these names. Basically, if you mistreat food by contaminating it, or by holding it at temperatures that permit growth, there is a possibility that numbers of pathogenic bacteria will increase to what is termed an "infecting dose" or that toxins will be secreted into the food. The latter cause food poisoning when ingested. So what is our favourite bloke going to do to keep himself and his family safe?
Easy - clean, cook, cover and chill. This little mnemonic includes it all: Clean-handle all foods with clean hands and utensils; Cook frozen foods after proper defrosting and use a thermometer to ensure that poultry or meat patties are properly heated through. If foods are to be reheated, ensure that the temperature reaches at least 75C right through to the centre; Cover cooked foods during cooling and place in the refrigerator within 30 minutes; Chill foods to 4C and hold at that temperature until served (remember that some bacteria grow readily at refrigerator temperatures, so even chilled food will not remain safe forever) or hold above 60C. You can find more extensive guidelines for these important concepts on the MAF website in New Zealand, or the FDA sites in America.
In the Southern Hemisphere, we are at the start of the barbecuing season. It's important to be really careful - never put cooked meat on the same plate as raw meat and pre-cook chicken legs etc. making sure that patties are heated right through.
I was once at a company barbecue, standing in line to collect my meal. I heard someone behind me whisper "See what he takes, he's a microbiologist". I didn't need to name the bacteria that might have survived on my meats, choosing only steak and thoroughly cooked burger patties.
Saturday, December 11, 2010
Make those bacteria do the 100m hurdles
When I was a kid (last century) at Grammar School in the UK, taking part in athletic activities was compulsory. One event that sticks in my mind is the 100m hurdles. It's important to get a rhythm going and take the same number of steps between the landing and takeoff for each hurdle. This seemed to go well for the first two or three hurdles, but it often became apparent that I was progressively falling short of my takeoff point for the later hurdles. Eventually, I either stumbled or had to take a couple of extra steps.
This principle is applied to modern food preservation. "Hurdle Technology" is a term coined by Lothar Leistner in about 1985. The concept is simple. Set up a series of "fences" and force bacteria to jump over them; if they don't fall at the first one, a later fence may trip them. In food, the fences are low levels of preservatives, modified atmospheres, special packaging, low temperatures, acid pH and so on. Some bacteria will be able to grow at refrigerator temperatures, but not in acid, or without oxygen etc.
There is a tendency among consumers to regard food processing as something sinister thought up by food technologists and done by manufacturers; fresh food is somehow better. In fact, by use of multiple hurdles, food can be kept for longer and the amounts of preservatives in the food are reduced without compromising safety.
This principle is applied to modern food preservation. "Hurdle Technology" is a term coined by Lothar Leistner in about 1985. The concept is simple. Set up a series of "fences" and force bacteria to jump over them; if they don't fall at the first one, a later fence may trip them. In food, the fences are low levels of preservatives, modified atmospheres, special packaging, low temperatures, acid pH and so on. Some bacteria will be able to grow at refrigerator temperatures, but not in acid, or without oxygen etc.
There is a tendency among consumers to regard food processing as something sinister thought up by food technologists and done by manufacturers; fresh food is somehow better. In fact, by use of multiple hurdles, food can be kept for longer and the amounts of preservatives in the food are reduced without compromising safety.
Monday, November 15, 2010
Do you really understand what's unsafe about your food?
There is a lot of concern about the safety of food. There is also a lot of misinformation and misunderstanding. Most of us have some concept of the dangers of the modern world, but our perception of risk, i.e. the probability that the hazard will become manifest, is often wide of the mark, perhaps influenced by publicity.
For example, most of us know that smoking is hazardous and that the risk of lung cancer and heart disease associated with smoking is high. Ask someone about the risk of flying in an airliner. If there has been a crash in the recent past, they may respond that flying is a high risk activity. The truth is that flying on a scheduled commercial flight is very safe. It's just that if an airliner crashes, it makes the news headlines all around the world, which influences our thinking.
Quite a long time ago, so long that I can't find the original reference, a few simple questions were put to food consumers. Food scientists assessed the actual risks. These people were asked "What is the food safety risk posed by the following?" What would your responses be?
Risk factor Perceived risk Actual risk
Microbial contamination Low High
Packaging failure Low High
Pesticide residues Medium Low
Irradiation High Very low
Recent events in the USA may have changed your perception, at least with respect to microbial contamination.
For example, most of us know that smoking is hazardous and that the risk of lung cancer and heart disease associated with smoking is high. Ask someone about the risk of flying in an airliner. If there has been a crash in the recent past, they may respond that flying is a high risk activity. The truth is that flying on a scheduled commercial flight is very safe. It's just that if an airliner crashes, it makes the news headlines all around the world, which influences our thinking.
Quite a long time ago, so long that I can't find the original reference, a few simple questions were put to food consumers. Food scientists assessed the actual risks. These people were asked "What is the food safety risk posed by the following?" What would your responses be?
Risk factor Perceived risk Actual risk
Microbial contamination Low High
Packaging failure Low High
Pesticide residues Medium Low
Irradiation High Very low
Recent events in the USA may have changed your perception, at least with respect to microbial contamination.
Monday, November 8, 2010
Time for red faces? Perhaps raw milk is not all it's cracked up to be.
The last time I wrote a blog on raw milk, I received "fan mail" accusing me of being sensationalist and closed minded. At risk of more unflattering comments, here is another post on the subject.
Proponents of raw milk consumption have long claimed health benefits of raw milk and products made from it. One of those claims is that lactose intolerant individuals, who don't produce sufficient lactase in the small intestine, suffer reduced symptoms if they consume raw milk, rather than pasteurised.
Stanford School of Medicine recently conducted a study of self-reported lactose intolerant individuals, who were given raw milk, pasteurised milk and soy milk in a randomized, double-blind, three-way crossover trial. This classic experimental design removes bias in experimenters and subjects. If lactose intolerant individuals consume lactose (the sugar found in milk) they cannot break it down to glucose and galactose. Anaerobic bacteria in the colon grow on the lactose and produce hydrogen, some of which enters the bloodstream and appears in exhaled breath.
The participants were tested for exhaled hydrogen on the first and last days of each 8-day exposure period. There was no statistically significant difference between consumption of raw or pasteurised milk, but soy milk resulted in much smaller amounts of breath hydrogen. Similarly, the symptoms reported - flatulence, abdominal cramping and diarrhoea - were the same for both raw and pasteurised milk.
The researchers reported that the results from their work, collected under standardised, controlled conditions, did not support the claim that, with respect to lactose intolerance, raw milk has benefits over pasteurised milk.
Meanwhile, raw milk and raw milk products continue to be linked with outbreaks of Escherichia coli and Listeria diseases
http://www.marlerblog.com/legal-cases/e-coli-and-listeria-in-raw-milk-and-cheese---growth-sectors-at-marler-clark/
Proponents of raw milk consumption have long claimed health benefits of raw milk and products made from it. One of those claims is that lactose intolerant individuals, who don't produce sufficient lactase in the small intestine, suffer reduced symptoms if they consume raw milk, rather than pasteurised.
Stanford School of Medicine recently conducted a study of self-reported lactose intolerant individuals, who were given raw milk, pasteurised milk and soy milk in a randomized, double-blind, three-way crossover trial. This classic experimental design removes bias in experimenters and subjects. If lactose intolerant individuals consume lactose (the sugar found in milk) they cannot break it down to glucose and galactose. Anaerobic bacteria in the colon grow on the lactose and produce hydrogen, some of which enters the bloodstream and appears in exhaled breath.
The participants were tested for exhaled hydrogen on the first and last days of each 8-day exposure period. There was no statistically significant difference between consumption of raw or pasteurised milk, but soy milk resulted in much smaller amounts of breath hydrogen. Similarly, the symptoms reported - flatulence, abdominal cramping and diarrhoea - were the same for both raw and pasteurised milk.
The researchers reported that the results from their work, collected under standardised, controlled conditions, did not support the claim that, with respect to lactose intolerance, raw milk has benefits over pasteurised milk.
Meanwhile, raw milk and raw milk products continue to be linked with outbreaks of Escherichia coli and Listeria diseases
http://www.marlerblog.com/legal-cases/e-coli-and-listeria-in-raw-milk-and-cheese---growth-sectors-at-marler-clark/
Sunday, October 17, 2010
Irritable Bowel Syndrome - good site
Irritable Bowel Syndrome (IBS) is still something of a mystery, but those who suffer from it are in no doubt that it is real. Many explanations have been advanced for it and various remedies have been proposed.
Though the subject is not really on the topic of safe food, I thought it would be good to provide readers with a link to a new website from the Marler Clark stable. The website is just about to go live, but here is an introductory link:
Though the subject is not really on the topic of safe food, I thought it would be good to provide readers with a link to a new website from the Marler Clark stable. The website is just about to go live, but here is an introductory link:
http://www.foodpoisonjournal.com/2010/10/articles/foodborne-illness-outbreaks/irritable-bowel-syndrome-and-postinfectious-ibs/index.html
Sunday, September 26, 2010
Where's my PhD student?
I had a scheduled meeting with my PhD student this morning, but she didn't turn up. I got a somewhat graphic text message, saying that she had food poisoning. It seems that she, her partner and two friends went out for dinner in a restaurant in Auckland on Saturday. They all appear to have food poisoning.
Of course, this doesn't prove that the restaurant was responsible. Indeed, her description of the symptoms and time of onset make me wonder if another common source was involved.
However, a TVNZ One News investigation shows that on average, one Auckland food establishment per week has been shut down this year because of safety or cleanliness violations.
An Auckland City Council Environmental Health spokesperson said that the increase in closures was a result of tougher action by health inspectors in response to unsatisfactory performance and suggested that this was partly because of the economic recession - companies were selling food that would previously have been thrown out.
A disturbing statistic given in the TVNZ report is that over 100 restaurants and cafes are still operating, despite poor hygiene ratings, though to be fair, businesses are given the opportunity to clean up their act before being closed down if they don't improve.
This report begs the question "If inspectors had previously found unsatisfactory conditions in food outlets, why didn't they close them down at the time? What has changed in the requirements to serve wholesome, safe food in clean premises?"
Of course, this doesn't prove that the restaurant was responsible. Indeed, her description of the symptoms and time of onset make me wonder if another common source was involved.
However, a TVNZ One News investigation shows that on average, one Auckland food establishment per week has been shut down this year because of safety or cleanliness violations.
http://tvnz.co.nz/health-news/shocking-food-hygiene-figures-auckland-3800902
An Auckland City Council Environmental Health spokesperson said that the increase in closures was a result of tougher action by health inspectors in response to unsatisfactory performance and suggested that this was partly because of the economic recession - companies were selling food that would previously have been thrown out.
A disturbing statistic given in the TVNZ report is that over 100 restaurants and cafes are still operating, despite poor hygiene ratings, though to be fair, businesses are given the opportunity to clean up their act before being closed down if they don't improve.
This report begs the question "If inspectors had previously found unsatisfactory conditions in food outlets, why didn't they close them down at the time? What has changed in the requirements to serve wholesome, safe food in clean premises?"
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