Monday, November 5, 2018

Downside of reusable shopping bags?

Supermarkets in New Zealand are discontinuing the use of single-use plastic bags as a contribution to reducing plastic pollution.  (My personal view is that this is just scratching the surface of the problem - produce is still wrapped in plastic and just about everything we buy in the line of detergents, shampoos, hand creams, water etc. is packed in plastic).

Some supermarkets are offering free or very inexpensive fabric bags to carry home the purchases.

A New Zealand politician has jumped on this, quoting a discredited overseas study that suggests that the use of reusable fabric bags will result in some deaths from food poisoning.

The general opinion among experts, myself included, is that this is silly scaremongering.  If meat and poultry is carried in these bags and blood or drip escapes the packaging, then the bag will be contaminated.  If unwrapped salads, cured meats, cakes, pastries and bread are carried in the same bag, cross contamination may occur.

Just as in the kitchen, it is sensible to separate raw meats, which will be cooked, from foods that will be consumed without further cooking.  Different chopping boards should be used for raw and cooked foods, and fabric bags used for raw meats should be washed regularly.  This not rocket science.

Others have jumped on the bandwaggon, once again putting forward the suggestion that sale of raw chicken, which often contains Campylobacter, should be banned in favour of frozen products.  Certainly, freezing reduces the numbers of Campylobacter, but does not eliminate it.

It seems to me that a slight change in mindset is required, together with a greater understanding of food hygiene.

Tuesday, October 9, 2018

13,000 beef animals just went to the landfill

I hope that caught your attention.  I suppose you could argue that it was clickbait.  The animals didn't literally walk to the landfill, but 6.9 million pounds of ground beef were recalled last week by a company called JBS because of fears that the meat was contaminated by Salmonella enterica serotype Newport (otherwise known as S. Newport).

There is a really good article on this recall by Joe Fassler in The New Food Economy.

FSIS was notified of a salmonellosis outbreak on 5th September 2018 and subsequent traceback indicated that JBS was the common source.  By 6th September, 57 patients in 16 states were identified as having Salmonellosis.  The strain of S. Newport in this outbreak is being reported as being multiple antibiotic resistant, though, as far as I am aware, this reporting is based on previous outbreaks.  Antibiotics are not normally used in treatment of human salmonellosis.   Experts have also pointed out that cattle are the most common source of S. Newport.

As with many large outbreaks, the situtation is at best muddy.  In general, Salmonella is found much less frequently in cattle herds than in chicken flocks.  It is not considered an adulterant by the regulators.  In some herds, the incidence of Salmonella  is zero; in others it has been found at up to 53%.  Salmonella enters the meat as a result of faecal contamination, from the animals or from the processing equipment.  Processors are not required to test for Salmonella, so JBS would not have been aware of its presence in its products.  Dairy cattle are not bred for meat production, but sick, low yielding cows are often culled and sent to meat works, where the meat, not being primal cuts, is ground and used with other meat in burger patties.  Thus, the potentially contaminated meat is spread extensively throughout the production.  You might argue that the company should test its products for Salmonella even though this is not a requirement.  However, microbiological testing is actually unreliable as a food safety control, mainly because of the problem of getting a meaningful sample from the food, particularly if the contamination is at a low level.

Since the processors are not required to test for Salmonella, they cannot be compelled to recall the potentially contaminated product, but JBS has done this voluntarily.  Well done!

However, several questions remain: why was this meat implicated in causing salmonellosis?  There are probably many answers to this.  Americans like their hamburgers rare or medium rare.  USDA raised the minimum temperature for cooked hamburgers to 160 degrees Farenheit (71.1 degrees Celsius).  Provided that this internal temperature is reached, Salmonella will be killed.  But kitchen hygiene is also critical.  If raw hamburger patties or mince are handled, cross contamination to other equipment, surfaces and foods can occur.  (Think next time you barbeque meat patties: did your utensils contact the raw meat and then the cooked meat?  I once attended a Korean BBQ where raw meat was put on a plate and then cooked before being put back onto the same plate!)   Was the processing equipment thoroughly washed down and sanitised after each shift, or is there a possibiliy that the bacteria had colonised the plant, allowing continuous inoculation of the product?  Certain designs of equipment are notorious for being very difficult to clean and providing niches for colonisation.

A more general and worrying question:  S. Newport is most commonly found in cattle and antibiotics are not normally used in treatment of human salmonellosis.  Why are we finding multiple antibiotic resistant S. Newport strains?

Take-home message:  treat all meat as potentially contaminated with pathogens like Salmonella.  Handle it carefully and cook it properly.

Monday, August 20, 2018

Wines by modern Prometheus?

I recently read an article entitled 'Frankenstein wine' warning over French supergrapes.

Apparently, French wine scientists have developed some vines that are impervious to fungal attack, specifically downy mildew and powdery mildew, and therefore requiring little or no fungicidal chemicals.  You'd think that this was a good thing and would be welcomed.  But no, some people, who may have a vested interest in turning back innovation, are claiming that the "lab-grown creations" combine genes from around the world and could lead to dumbed-down, low-grade "Frankenstein wine", whatever the hell that means.  The implication is that the new varieties are somehow unnatural.  As far as I can tell, genetic engineering has not been involved; conventional cross breeding has been used.

Let's just step back from this hysterical attack on scientific improvement in winemaking.  As a result of claimed cancer links among grape growers, the French are under intense pressure to reduce the amount of fungicides used.  The use of these new varieties would therefore seem to be a good move.  However, a winemaker and researcher from western France has claimed that these vines, which are  hybrids, would lead to "artificial and unnatural 'Frankenstein wine'."  According to the article, he likened the development of the new vines to crossing a monkey with a man - technically feasible but going against nature. That is a completely over-the-top reaction, but I'd be keen to see the resulting animal!

The development and growing of hybrid grape varieties has in fact been going on since the 1950s in the northeast and Pacific Northwest of North America.  Those varieties have enabled production of wines in these short season, cooler and more humid areas.  They also have greater resistance to disease and therefore require less use of chemicals.

Though rare, natural interspecific hybrids do occur as a result of cross-pollination, the earliest known was discovered in 1740 near a vineyard planted in Vitis vinifera.

Tuesday, August 7, 2018

FDA issues an update statement on Yuma E coli outbreak

Earlier this year, a serious multi-state outbreak of Escherichia coli O157:H7 infection was associated with consumption of Romaine lettuce from Yuma, Arizona.

The US FDA has now issued an update statement, though the investigation is not completed.  Tests of canal water close to the lettuce growing farms has tested positive for the outbreak strain of E. coli O157:H7, which is capable of producing Shigatoxin.  Infection with this microorganism can result in serious disease - 210 people in 36 states have become ill, with 96 hospitalizations and five deaths.

No single farm has been determined as the source of the outbreak, nor has the distribution chain been implicated so far.

The lettuce growing farms and canal are close to a Concentrated Animal Feeding Operation (CAFO), which can hold in excess of 100,000 head of cattle at any one time.   Since cattle can harbour the STEC E. coli involved in the outbreak, there is the possibility that the presence of the bacteria in the canal water originated from the CAFO.  Further testing of the CAFO and the animals would be necessary to establish a link.

The means by which the lettuces became contaminated must also be investigated.  Was the canal water used directly for irrigation, or were the bacteria somehow transferred from the canal water to the leaves?

Thursday, August 2, 2018

Safe Food - Product Lifetime of the blog

All products have a lifetime, after which sales drop off.  The usual response is either to discontinue the line, or to set the New Product Developers (NPD) to updating the product.  Think of ice cream.  There will probably always be a market for ice cream, but the flavours of your childhood have been surpassed and the presentation has changed dramatically.  You now have the options of ice creams on sticks, with creamy toffee, chocolate or fruit puree centres, coated in chocolate and nuts etc.

Safe Food first appeared in November 2006 while I was working at Hong Kong University.  The wide varieties of foods in HK are completely different from those of our adopted country, New Zealand, though the safety issues are similar.  I felt the need to write about the hazards associated with foods to help ordinary folk and food manufacturers to understand food safety, with the aim of reducing the incidence of food-mediated illness. I hoped the blog would become a resource for teachers in schools.

I have no idea whether these lofty aims were successful!  The blog has only 10 followers 😢 but in the 12 years I have been writing it, there have been nearly 348,000 page views, so I guess that means that some people have found it useful.

Very few people have left comments on the blog, though some have contacted me directly - usually young mothers who have had food scares with their babies and young children.

There are only so many unique food safety incidents to report on.  Often contamination and recalls merely reflect the sad fact that manufacturers, distributors and consumers don't learn from earlier incidents.  This is one of the reasons that Safe Food has not been published so frequently in the years since I retired from full time teaching and research.  Perhaps the blog has become stale and "same old, same old".

It's time for some NPD!  I have decided to continue writing the blog, but I want to widen the scope just a bit so that I can comment on some of the food myths that are now so frequently proliferated by minor celebrities, fanatics and those who can best be described as "loonies".  There are exciting new developments in foods, such as the plant-based milk and meat substitutes, most recently exemplified by Air New Zealand's offering The Impossible Burger on some of its flights, and I want to discuss these evolutions in food supply.

I may also update the appearance of the blog, so, watch this space and please consider following.

Wednesday, August 1, 2018

I've been served some pretty awfull coffee in my time ...

Many people on Twitter are reporting that a pregnant woman in Alberta ordered a latte at a McDonald's but was served a cup containing cleaning fluid.

According to a report on CBC News, this was caused by the coffee machine still being connected to two cleaning solution supply lines, rather than the milk reservoir.  The cleaning chemical was a mixture of citric acid, phosphoric acid, methyl-trimethyl-3, and 2-butoxyethanol.  There is no doubt that ingestion of this material would be harmful.

It's not clear whether the cup contained hot liquid, though if the machine were set to deliver coffee, but connected to a cleaning chemical supply, it's likely that the cup did feel normal, and since it was a takeaway, it would have been fitted with a lid, so gave no indication that it didn't contain latte.

This potentially very dangerous incident gives a lesson:  if you are a pilot, a car driver, or the operator of a food processing machine, the principles are pretty much the same - the pre-start checks must always be conducted before any start and done properly.

Sunday, June 3, 2018

E. coli strikes again

Five people in the United States have died since March and approximately 200 are sick as a result of an Escherichia coli infection apparently acquired from romaine lettuces grown in the Yuma region of Arizona.  However, the authorities have been unable to pinpoint the source of the contamination.

Though E. coli are found in the gut of man and animals, only certain strains cause serious illness.  These strains have assembled many genes that enable them to attach to the cells lining the intestine and produce very damaging toxins called Shigatoxins.  This is an example of the continuous evolution of bacteria.  Many of these new strains are the result of bacteriophage infection transferring genes between bacteria or possibly by direct transfer between strains.

Various posts responding to news reports of the outbreak have suggested washing the lettuces as a means of preventing illness.  Unfortunately, washing, even in chlorinated water, will not guarantee removal of the bacteria, as they can attach to the lettuce or even localise in the stomata of the leaves.  I obtained the following image from

You can see bacteria within the stoma; it is clear that they would be very difficult to wash out.

This outbreak was originally thought to be caused by bagged and chopped lettuce, but inmates in a prison in Alaska also became ill after eating whole head lettuce.  In view of these facts, it is unfortunate that consumer advocates are urging the FDA to introduce new rules to speed up investigation of such outbreaks.  It is hard to see how new rules would influence the investigations, given that it has so far been impossible to tie the contamination to a single farm, processor or distributor.

The one fairly sure conclusion is that the lettuces have become contaminated with faeces, since this E. coli is not a natural inhabitant of the environment.