Wednesday, December 14, 2011

Cancer and spices.


Anonymous asked: "Do ginger, curry powder and cumin powder help reduce risk of any cancers? "

Disclaimer:  I am a food chemist and any medical comments are those of a food chemist.
Will anything prevent cancer?

No, probably not.  Cancer is not one disease but a diverse group of illnesses, all characterised by uncontrolled cell growth.  Cancerous cells are being produced all the time and the body deals with them.  The problems arise when the body can no longer deal with them.  This will be partly why cancers are more prevalent in the elderly; the body’s defences get weak, lazy or ineffective.

I believe that pretty much anything will cause cancer – if the body gets swamped with any chemical, systems can go awry.

But will anything prevent cancer?   I don’t believe so.  At least not any one thing.

Good diet and good health seem to be part of the cancer preventative thing :  be healthy, give your body a chance.  Let your body function as it should, defences work properly, cell reproduction work reliably.

I have little doubt that the individual components of ginger, cumin and curry powder will trigger cancers if taken in excess.  Anything taken at a level that distresses the body increases the likelihood of the body malfunctioning and cancers being the result.

But I really have no knowledge on compounds, natural or synthetic, that may directly work to prevent cancers.  And I think it unwise to pin your hopes on a 'silver bullet'.

Sunday, October 30, 2011

Take it with a pinch, no, a bag of salt!


Food Australia, who should know better, published an article earlier this year titled "Contaminated reusable grocery bags pose health risks" (63 (5) - May 2011). It was based on an article by Gerba & Sinclair entitled "Assessment of the Potential for Cross Contamination of Food Products by reusable Shopping Bags". You can download the full article here.

The article suggests bacteria, including E. coli, flourish in the green bags.

And the are probably right. The same way bacteria can flourish in pretty much any environment. Because bacteria is IN the environment. If they had done their survey by swabbing the jeans of the shoppers rather than the bags, they would have got similar results.

And as for soaking the shopping bags in meat juices and leaving them in a car boot (trunk) for two hours - well, duh!, of course bacteria levels will increase.

It was all a bit odd and I had a niggling suspicion, which is why I chased down the original article rather than relying on the summary in Food Australia. My suspicion was confirmed in the following line:

"The authors would like to acknowledge and thank the American Chemistry Council for providing funding to support this study."

So, the American Chemistry Council, a body that includes all the plastic (bag) manufacturers of America in its ranks funded the research.

Doesn't mean it's wrong but there are flashing lights all over it!

Monday, August 29, 2011

Not ducking the question.


Celia of Fig Jam & Lime Cordial, asks

"I've been making confit duck, and keep it for a short time in the fridge.

1. As instructed, I've been reheating the used duck fat to clarify it and then storing it in the freezer to be reused next time - is this a safe practice, and how many times can the fat be reheated and reused like this, please?

2. Secondly, confit duck (a traditional food) has been stored for generations by the French on the pantry shelf, with some instructions going so far as to say "don't worry if the bones not covered in fat go a bit green". I don't do that, I keep it in the fridge, but wondered whether it was actually safe to store meat like this unrefrigerated?

Question 1. It is a matter of taste. Over time there is a likelihood that the fat will start breaking down but that in itself is not harmful. The issue is whether the taste is affected. My Granny had a 'dripping pan' that used to hold fat that was returned time and time again to the weekend roast, with no ill-effect. Animal fats are generally too saturated to have oxidative rancidity and hydrolytic rancidity (the splitting of the fatty acids from the glycerol backbone of the fat) often cannot be tasted. A text book I read once famously said that a fat was rancid if it tasted rancid and that all other tests were, at best, just corroborating evidence.

The splitting of the triglyceride happens during digestion so it is no a health hazard as such.

So, in short: as long as the fat still tastes ok, it is fine.

Question 2. The fat layer is supposed to keep the meat protected. Despite what advertisers of disinfectants and such like would have you believe, bacteria do not spontaneously appear for no good reason. This is a habit solely retained for the start of a new Universe. If your duck is cooked, it will be sterile and the thick layer of fat will keep it sterile.

Has done so safely for many many years.

Green is more problematic but not necessarily harmful. The pigments in blood - haemoglobin and myoglobin, will oxidise and go funny colours, mostly green, grey and brown, with exposure to the air. Unsightly but not harmful. The surface of the chicken paté I make discolours quite quickly but is not harmful.

More important is to make sure that the exposed bones and such like are not handled as they do not have the layer of protective fat and will possibly give bacteria a toe-hold.

Sunday, August 21, 2011

Stamps. And the perils of licking them.

Stamp commemorating all that was left standing after the US 'liberated' Iraq?

Xink asks: Is it possible to die from licking stamps? As in the Seinfeld episode when George Costanza's fiance dies after licking cheap stamps for a wedding invitation mail out.

Good grief - we get further and further away from food chemistry!

Partly my own fault: My profile has a question on it: "What's the best time you've ever had licking stamps?" My response was "Ah, Stamps! Such a lovely girl. So many memories; how can I choose?" So I guess I have no-one to blame but myself.

The short answer is that I do not know of anyone dying from licking stamps but the mucilage that was put on stamps to act as the adhesive is a protein based material and, as allergenic reactions are generally a response to proteins, it is not impossible that someone may have a reaction.


As for the Stamps of my profile. Yes, if her boyfriend found out, that could kill you.


Thursday, August 4, 2011

The Hormonal Cow


Celia asked: Lee, do you have any thoughts about growth hormones in Australian beef and what they're doing to us?

Well, yes, I have thoughts. Mixed thoughts.

I don't have too many facts, though, as it is a bit outside my experience.

Thoughts, in no particular order:

1. I have a general preference for no additives in food (don't you dare call them 'chemicals' unless you can name one thing on this planet (and beyond) that is not composed of chemicals) however I accept that sometimes additives to food are unavoidable.

2. The Safemeat site suggests that hormones are not harmful but that, while they increase meat yields, they decrease meat tenderness. This site is a joint venture between the meat industry and the Government.

3. Talking to another laboratory that tests HGP (Hormone Growth Promoters), they can only reliably find them in the area surrounding the injection point in the cow's ear. In other parts of the body they are too low to quantify.

4. Like it or not, we must increase our food production to meet the population growth; farmland is decreasing, so per-acre yields must increase. But we eat too much meat per meal, as a rule.

5. There is little evidence available to show that the nature-identical hormones are harmful. I am probably more comfortable with them than I am with the fully synthetic ones.

6. I would favour mandatory labelling.

So, in summary, I don't think they are harmful but would prefer they not be used.

But I am no expert.

Wednesday, July 20, 2011

Steak Tartare


Celia, of Fig Jam & Lime Cordial, asked "Does the traditional food rule apply to dishes like steak tartare?"

Yes, is the short answer.

Steak Tartare is a traditional food.

Despite the rantings of Professor A. C. Grayling, philosopher and vegetarian irrationalist, meat is not full of bacteria. (See here) Once you cut it, though, bacteria is introduced and the life of the meat starts being reduced.

A number of things need to be remembered:

  1. The amount of bacteria that you introduce in chopping the meat is quite small. Especially if you take care to use clean knife.
  2. Bacteria, at room temperature, will double in numbers every 20min, so what starts out as a low level can rise very quickly.
  3. Most spoilage bacteria is just that, spoilage bacteria. Pathogens, such as E-coli or Salmonella, are less prevalent and less likely to be introduced in the chopping of the meat.
  4. The concept of an 'infectious dose'. Everyday we are ingesting low levels of bacteria, including pathogens, with no ill effect. There is a certain level that is necessary to induce illness.

The long and short of it is that Steak Tartare must be made fresh and eaten fresh.

That is the traditional way to do it.

And it is quite safe.

Sunday, July 17, 2011

Sunscreens, SPF 50


Much excitement in Australia this week with the granting of permission to sell SPF 50 sunscreens.

Got to be 66% better than all those SPF 30 ones, mustn't they?

Well, hold you horses. Could it just be marketing hype?

To get the SPF factor, you divide 100 by 100 minus the percent of the UV radiation blocked.

So if a sunscreen blocks 90% of the UV light, its SPF is 100/(100-90) = SPF 10.

95% = SPF 20

97% = SPF 30+

98% = SPF 50.

So paying the extra money for an SPF 50 sunscreen will increase your protection by just 1%.

If (IF!) it is re-applied regularly and applied at the same thickness as is used in the test (0.1mm).

T-shirts and a hat have a higher SPF factor.

Tuesday, March 22, 2011

Smells dead, must be dead.


Chairman Bill asked: "How about trassi? I've heard some hideous stories about it, although I've eaten plenty of it in my time (both as a Dutchman and when in Indonesia/Malaysia)"

This is an amazing fermented dried shrimp paste that smells awful but tastes wonderful.

The big thing is that this is a traditional food; a pretty reliable sign of a good track record for safety.

And the traditional way of cooking it is to stir-fry in a very hot wok. This will kill any bacteria that may be in it. Deviate from traditional cooking processes at your peril.

It must also be remembered that it is usually a dried product and so lacks the available water needed for bacterial growth.

Monday, March 21, 2011

Of meat and fridges...


The Intolerant Chef asks: "How long can raw meat be kept in the fridge before being harmful? I remember my mother washing slightly bluish looking chops in vinegar and water to remove the stickiness and smell before cooking them. They were then fed to my father, never us children or her."

I assume your father was well insured.

Generally, fresh meat can only be kept for a few days at refrigeration temperatures. It is hard to butcher meat without getting bacteria on its cut surface and bacteria love a warm, protein rich surface.

Note: these are bacteria introduced during the butchering process and not endemic to the meat as such. When the meat is 'hung' after slaughter, the surface of the carcass is dry and intact and no bacterial degradation takes place. Once the meat is sliced or minced, bacteria is introduced and all bets are off.

Chilling meat slows bacterial growth but doesn't stop it. Freezing it stops the growth. As does drying.

Bacterial growth results in the breakdown of proteins which in turn produce the unpleasant smells that we associate with 'off' meat. Rubbing the meat with vinegar may reduce the bacterial load and reduce the smell. Traditionally curry was also used to hide off meat.

It would be the thorough cooking afterwards that killed the bacteria and made it safe for your father to eat.

Probably with lots of sauce.

Friday, January 21, 2011

The Mayo Clinic


Don says:

"I had the wonderful privilege of touring Mullins Food Products, Makers of mayonnaise.. "(Mayonnaise) doesn't even have to be refrigerated. No harm in refrigerating it, but it's not really necessary." He (the food chemist) explained that the pH in mayonnaise is set at a point that bacteria could not survive in that environment.

(The food chemist) says that when food poisoning is reported, the first thing the officials look for is when the 'victim' last ate ONIONS and where those onions came from (in the potato salad?). Ed says it's not the mayonnaise (as long as it's not homemade Mayo) that spoils in the outdoors. It's probably the onions, and if not the onions, it's the POTATOES.

He explained, onions are a huge magnet for bacteria, especially uncooked onions. You should never plan to keep a portion of a sliced onion. He says it's not even safe if you put it in a zip-lock bag and put it in your refrigerator. "

Ye gods! Where do I start?

The easy bit first: see a previous post on the myth of onions being bacteria magnets. Make sure you read the comments, as the saga went on for a while.

Secondly, there is a popular myth (only in the US for some reason) that mayonnaise is a chief culprit in food poisonings. It isn't. Or at least commercial mayonnaise isn't, as it is made in strictly controlled conditions.

  1. The pH of mayonnaise is kept low, at a level that bacteria cannot survive.
  2. The water activity of mayonnaise is low, meaning that the moisture present in the mayonnaise is not available to the bacteria (or mould) to use and
  3. the product is made in sterile conditions.

The consequences of that last item eludes many people. They think that bacteria just happen. That is as sensible as watching a field, hoping for corn to grow. If you don't plant it, it wont grow.

And "if not the onions, then the potatoes"?

Anything that grows in dirt can have bacteria on it. It will be in an environment where there is E-coli, Salmonella, Clostridium, lots of bugs with long and threatening names. Wherever birds poop and animals roam will have bacteria. You meet up with them every day of your life. And survive.

But if you take some potatoes and cook them there will be no bacteria alive on them.

Put them in a potato salad with mayonnaise and they will still have no bacteria on them.

The biggest problem is when you add bacteria to the salad yourself and then leave the salad sitting unrefrigerated for hours on end. At room temperature bacteria multiply tenfold an hour.

So where do these bacteria come from? Spices, raw unwashed vegetables and, most commonly, poor personal hygiene when preparing the food.

But from the mayonnaise? No.

From onions? No.

From cooked potatoes? No.