JUST TO SHARE (Lau Tai Onn): 3 Foodstuffs To Avoid & Food Quality Control

The blogger has recently received an email from his present company's secretary (soon to be an ex-colleague after end of August) and he forwarded it to a few e-buddies. Below are the original email and remarks from Dr JB Lim:

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Recent announcement from the TV News from Beijing:

Toxic Century Eggs made in China.

Century Eggs are called ‘phee tarn’ in Cantonese. The egg white has become black & the egg is normally eaten with sliced ginger. The news reported that it normally takes 3 months to make the Century Eggs, but some crooks in China discovered that if they ALSO soak the eggs in INDUSTRIAL GRADE Copper Sulphate, the whole process can be shorted to just 1 month! However, Copper Sulphate is bad for health. The crooks were arrested in ChongQing. The news also warned people NOT to buy century eggs offered for sale in supermarkets since there is NO way of knowing whether those eggs have been soaked in Copper Sulphate. It is possible that some of these eggs are exported to Malaysia. So it is better for you not to eat them.

Fake honey

A very dirty warehouse was raided somewhere in China, & in it crooks were using chemicals to make fake honey! So don’t buy any honey that comes from China. The best honey is produced in Australia & NZ. Manuka honey produced in NZ is supposed to have curative properties.

Fresh fish or fillet fish

It was reported that the Japs cod fish off the coast of Fukushima, where there is radioactive contamination, was sold to some HK fishermen very cheaply. The Hkies then sold the fish to SEAsian countries claiming that the fish were cod from HK waters. So, beware! It is best to eat local fish. The Mekong River is highly polluted with toxins like Agent Orange dioxins dropped by the Yanks as defoliants during the Viet war. Fish caught in Vietnam have even reached Aust! So beware of cheap fish on sale in the market!

(Courtesy of forwarded mail from Eileen Ho)

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On Wed, Jul 31, 2013 at 3:35 AM, lim juboo wrote:

Let me tell you as a full-fledged analytical food chemist as part of my Food Quality Control and Food Safety training on how do you detect copper, sodium, potassium or any other elements in a food sample or in any sample in the simplest way which you can easily do in your home kitchen.

All you need is a platinum wire to dip the end of it in concentrated hydrochloric acid to pick up a tiny sample of the food you suspect to contain copper sulphate, or any copper compound (or other elements you suspect may be toxic).

Next pass the platinum wire containing the sample moisten with the HCl into the hottest part of a Bunsen burner. If there is any copper in it, the flame will turn into a brilliant greenish colour. For potassium it will be liliac, sodium, yellowish, or if you suspect arsenic, it will be blue in colour, and so on, and on down the list of elements.

If you do not have a Bunsen burner, not to worry! Use the flame from your kitchen gas stove. You can buy a short piece of platinum wire from any shop that sells scientific instruments, chemicals and apparatus to school labs.

Actually we hardly use the flame test for our chemical analysis these days. In my undergraduate days, we use wet chemistry for group analysis to separate and identify various kinds of mixtures of salts given to us for analysis. This analytical procedure is quite complicated and very lengthy and can take the entire day. This also requires quite a bit of understanding on chemistry, and analytical chemistry.

But in my postgraduate we use much more sophisticated analytical procedures like the atomic absorption spectrometry to detect characteristics absorption and emission lines in the spectra.

Other forms of spectrometry can also be used depending on the nature and complexities of the chemical analysis. But all these can only be carried out by a professionally qualified and registered chemist (Chemist Act 1975) in an advanced analytical laboratory. Normally we follow the AOAC protocol in food analysis. It depends on what we are looking for?

But for BOGUS chemists inside the home kitchen, the simple flame method using a platinum, or a nickel- chromium wire (platinum is better) will do, except you cannot quantify how much copper, arsenic, lead, cadmium, etc, etc are there inside your food sample. The flame tests are just for detection.

For quantitative analysis even to the extent of detecting parts in billions (ppb), you need to use wet chemical analysis (less sensitive), or switch to sophisticated instrumental methods in an advanced analytical chemical laboratory where it can only be performed by a professionally qualified chemist.

But for BOGUS chemists, just buy a 4-5 cm platinum wire sealed into a glass rod, small bottle of concentrated hydrochloric acid, a watch glass to place your food or any sample on, and use your kitchen stove flame instead of a Bunsen burner.

You can buy all these very simple things from any companies selling scientific apparatus. There is one (Progressive Scientific Sdn Bhd) just less than ½ km from my house in Batu Caves.

There you are! I have already taught you how to become a BOGUS analytical chemist and a food quality controller (but a very effective one) to detect poisons in your food.

There are many other 'simple' home kitchen tests for other food poisons you may use, but if I were to teach you all these tests I might as well write a book and sell them like hot cakes the world-over. I think everyone especially housewives in the kitchen and health conscious people would be interested in buying such a book.

jb lim

BSc (Chemistry), MSc (Food QC)

An Analytical Food Quality and Food Safety Controller (but now BOGUS after retirement)

Formerly, Research Medical and Nutrition Toxicologist, MIT

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On Fri, Aug 2, 2013 at 11:48 PM, c kwong Cheong wrote:

Dear Dr Lim,

Thank you very much for the information, must try it out.

by the way can we use gold wire ? as gold is also stable and not easy to form salt.

Regards,

C K

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From: lim juboo

3 August, 2013 at 2.33AM

Dear CK,

Thanks for asking.

Yes, for the flame test may use gold wire to detect the presence of a lot of elements (some of which are toxic, example arsenic, mercury, cadmium, lead, copper, etc) you suspect may have added into your food.

Platinum and gold are Nobel metals that resist concentrated hydrochloric acid attacks even at high temperatures of a Bunsen or a kitchen propane gas flame in air. Naturally gold will not be easily attacked by strong hydrochloric acid (HCl).

However, if you intend to use a gold wire instead of a platinum, you may have to use a thicker gold wire, thinner for platinum. I have reasons to suggest this because gold easily melts at the temperature of a Bunsen flame which is around 1,400 – 1,600 deg C if you keep your gold wire in the flame for a long time, especially if the wire is too thin.

You have to understand the melting point of gold is slightly over 1064 deg C and the test flame of your kitchen air-propane is 1980 deg C which is well above your melting point of gold.

Our Malaysian stove gas is actually a mixture of butane and propane, with the air-butane mixture flame temperature at 1970 deg C which is just 10 deg C lower than that of air-propane.

Whether butane or propane air-gas mixture, they will attain a temperature well above that of the melting point of your gold. Even platinum with a melting point at 1768 deg C may just be able to resist melting in such a air-gas flame, whether in a Bunsen flame or in the blue flame of your kitchen stove. This is true at least in theory.

However, in practice this may not be so, because as you subject your gold or platinum wire in such a flame, the convention and flow of hot gas upwards, you instantly cool the wires well below the melting point of your gold wire.

In short, the flow of gas will extract the accumulated heat as the wire is being heated. This is very simple scientific logic of physics and chemistry, and you do not need to have a PhD to think this way.

But you were right Au (gold) may be substituted for Pt (platinum) provided you do not use an oxy-acetylene torch where the temperature will reach a searing 3500 deg C to conduct your flame tests. Both Pt and Au will instantly melt within seconds using an oxy-acetylene flame.

Another thing I need to tell you is, almost all foods contain sodium even without salt being added. In fact sodium is a very common compound present in almost all foods, including fresh and unadulterated ones. The presence of sodium will give a yellow flame. So if you have copper salts added inside you may find it difficult to see the brilliant green flame of copper.

Not to worry. Just buy a small piece of blue cobalt glass along with your Pt / Au and concentrated HCl from a scientific supply company. Then view the flame through a piece of cobalt glass. The yellow colour of sodium will be cut off, and you should be able to see the green colour or the other different colours of other elements. There is a table of the colours associated with various metals or elements you are trying to detect.

One more thing! Do clean your Pt or Au wires after each test. You may do this under running water, and repeatedly pass the wire through the flame, wash again, repeat until there is no more colour to the flame.

Alternatively, you may also clean the wire by dipping it in conc HCl, pass it through the flame, and repeat the process until there is no more colour.

Actually Pt wire is very expensive. A 20 cm wire can cost up to RM 300. What you need to do after buying the wire is to soften one end of a glass rod in your Bunsen or kitchen flame, and insert one end of the wire about ½ cm into the glass rod. Cool it, and it is sealed inside your glass rod. Soften and round the other end of your glass rod also.

The glass rod may be about 15 cm (6 inch) long. Insert the glass rod into a rubber bung or a cork with a hole in the middle. Buy also a boiling tube or test tube, and keep the wire cocked up inside the tube when not in use, may keep this inside your kitchen and use it at any time you suspect undesirable metals have being added into your food.

You don’t require a sophisticated analytical research lab for this. This is only meant for professionally qualified analytical chemists who use highly expensive, technically high flown instruments, such as HPLC, and other chromatography, atomic absorption spectrophotometry, atomic emission spectroscopy, inductively coupled plasma atomic emission spectroscopy, spectroradiometry, slope spectroscopy for sophisticated analysis.