Thursday, June 5, 2014

At last, a different onion question!

Anonymous asks: "Would like to know if you can get sulphuric acid poisoning from rotting onions? Had a bag of onions in my cupboard for months and they had rotted now all I can smell is onions. Really strong at times. "

A few bits to this:

Firstly, sulphuric acid is not volatile, so you cannot smell it.   Heat it sufficiently and you will get sulphur trioxide fumes which you can definitely smell but I am talking 400degC, somewhat warmer that the average cupboard.

Secondly, it is corrosive rather than toxic.

But on to the onions.  When things rot, all manner of compounds are formed and released.  What compound and what level will be dependent on onion type and the organisms associated with the rotting.  Onions contain a lot of sulphur so the breakdown products will be smelly.  Unpleasant but not necessarily harmful.

Chuck them out and air the cupboard.  There is not much else you can do.

Monday, December 30, 2013

Nuts to that!

Reading an article in Food Quality New I was a bit confused about the about photo (above), said to be of pecan shells.  Well, there may be pecans there at the back but the foreground is all almond and brazil nuts.

For the record, pecans look like this:

The gist of the article, though, was about the use of dried, powdered pecan shells as a natural, organic antibiotic, specifically against Listeria sp.

I would just like to point out that natural and organic are not the sole criteria for food safety.  Strychnine, cyanide, arsenic and aflatoxins are all well encompassed by the 'natural and organic' umbrella.  OK,  arsenic's not organic.  Just testing.  Lots (I mean lots of lots) of things contain organic compounds that exhibit antibiotic properties when concentrated and deposited of some unsuspecting bacteria.

But nothing beats having the bacteria not present in the first place.

No amount of powdered hoodoo dust will trump good manufacturing practices and plant hygiene.

Thursday, February 16, 2012

Coffee, Tea...


Peter Bryenton asked "I was wondering how much caffeine there is on average in an ordinary cup of instant coffee?"

Not an easy question as the consumer is in control of how strong they make the coffee and how big a cup they use.  Generally instant coffee powder is about 2-3% caffeine and instant coffee is about 330mg/L (about 75mg per cup).  But I know my first cup of coffee in the morning is considerably stronger than my last of the day.

Tea is generally only about 80% of the caffeine levels of coffee but, again, this varies with type, cup size and steeping time.  Herbal teas generally have none but be careful of flavoured green teas, they have similar levels to black tea.

Colas are about 100mg/L; a third that of tea and coffee.

The much vaunted 'Energy Drinks' are only permitted a maximum of 320 mg/L in Australia and so are on a par with tea and coffee.  Not that they would want an image of a little old lady sipping her cuppa to be equated to the macho image of the heroic energy drink urban warrior-rapper-sportsman.

Sunday, February 12, 2012

Anticancer Spears


Kevin Bell asked: "Any info on the email going around that Asparagus is good for curing cancer? This also seems incredulous, the pharma industry are not stupid and would be onto it quickly enough if there was any credibility in it."

Well, yes, I think you nailed it yourself, Kevin.

If there was any truth in it, it wouldn't be being sold at $4 a bunch at Woolworths.

As I understand it, cancers are initiated when your body loses the plot with regard to cell regeneration and starts an uncontrolled multiplication. 

I can see no reason why a food, any food, would stop this.  I would be more inclined to believe that eating excessive amounts of asparagus would cause problems rather than the reverse.

Too much of anything is bad.

But moderate amounts of asparagus with a good home-made hollandaise sauce is not bad for you and, indeed, can improve your emotional well-being no end.

By the way, I haven't seen the email that you mention, but I am sure that the miracle chemical in asparagus will be Rutin.  Love the name.  It is a naturally occurring flavonoid found in a number of foods.  As well as in asparagus, it is also in buckwheat, citrus peel, mulberries and cranberries.  In canned asparagus it appears as white or grey flecks in the spears.  Something about the canning process triggers crystallisation.  Quite beautiful crystals under the microscope.

A load of old rhubarb


I made mention on my home blog that my rhubarb was green and that I was adding elderberries to it to make it look more 'normal'.  I have seen recipes that added strawberries to give colour.  A few people asked if green rhubarb was safe.

Yes, it is.

The green stemmed rhubarb is a fast growing, thick stemmed hybrid.  Quite safe.

The poisonous element in rhubarb is a chemical called Oxalic Acid and it is found at high levels (0.5%) in the leaves, regardless of the stem colour.

Oxalic Acid is also found in many other plants but not at the levels found in rhubarb leaves.  Excessive Oxalic Acid consumption results in kidney stones (Calcium Oxalate).  A lethal dose of rhubarb leaves is about 5kg.

Saturday, January 14, 2012

Potomatatoes & Acidity

Anonymous asked "Do totatoes can acidity in the body?"

Well, that is not an easy question to answer, as such.

Are we talking potatoes or tomatoes?
Are we talking cancel or cause?

Never mind - I'm guessing that it relates to the much discredited acid-alkaline diet that lingers in the fringe diet circles.   In essence, it proposes that foods are good or bad depending on the pH of a solution of the ash of the food.  The notion that the acidity or alkalinity of the ash of a food will influence the impact that the food has on your body is just plain weird.

There is no scientific data to support the theory.  There is not even a coherent theory.

Your stomach is already 100-1000 times more acidic than a tomato or a potato, so any native acidity will have a negligible impact.  No foods are natively alkaline.

As you body never reduces food to its ash, the properties of the ash are immaterial to human nutrition.

Eat a varied, balanced diet.

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'.