Food Fraud in Australia?

Congratulations to Dr Michael Smith, Associate Professor Mahmud Ashraf, Professor Chris Austin
and Associate Professor Rebecca Lester of  Deakin University on the publication of "Product fraud: Impacts on Australian agriculture, fisheries and forestry industries" (November 2021). This report gives a good, concise, overview of known recent agricultural product fraud from all over the world. While it can make for scary reading, it is a reminder to stay vigilant when buying food. Here is a little taste of what you will find in the report,

"Turmeric is considered highly vulnerable to food fraud, with
frequent incidents of contamination with lead chromate (a
yellow colourant) reported. A study found that seven of nine
turmeric-growing areas in Bangladesh showed evidence
of turmeric adulteration with lead chromate. Levels of lead
exceeded national limits by up to 500 times (24-9-19)."

You can download a copy of the report at the AgriFutures Australia website: https://www.agrifutures.com.au/product/product-fraud-impacts-on-australian-agriculture-fisheries-and-forestry-industry/

Examples of food fraud can be used when teaching chemistry. Students can calculate the concentration of milk or fruit juice after it has been fraudulently diluted, and then compare that to what is stated on the nutrition panel product label. You can learn a lot about the properties of chemical compounds and mixtures by making a fake egg or fake milk. You could used the adulteration of "manuka honey" to teach spectroscopy, or the melamine (1,3,5-triazine-2,4,6-triamine) in milk scandal to teach percentage composition or volumetric analysis. The pedagogical possibilities are limited only by the resourcefulness of the food fraudsters.

If you are looking for some more inspiration, try "Sorting the Beef from the Bull: The Science of food fraud forensics" (Evershed, R., and Temple, N, 2017). And yes, I may have bought it because it has such a great title ... you all know me too well 😉

 

Hydrolysis of Carbohydrates

Carbohydrates like disaccharides and polysaccharides can be broken down into monosaccharides.
In the lab we use acid hydrolysis, but in your body you use enzymes to do this.
AUS-e-TUTE has just added a new tutorial, game, test and exam to help you understand these chemical reactions. Members should log-in to access these new resources (under Biochemical reactions).
If you are not an AUS-e-TUTE member you can access a "free-to-view" tutorial at https://www.ausetute.com.au/hydrolysiscarbs.html

Energy Content of Food

As I read the"nutritional information" panel on my box of cereal this morning I wondered how you would measure the "energy content" of food.
At AUS-e-TUTE we've come up with a straight-forward experiment that you could do in the school laboratory (or at home if you really wanted too!). We even provided some sample results and calculations so that you can measure the energy content of your favourite foods.

If you are an AUS-e-TUTE Member, you will also find additional resources such as a game, test and drill with worked solutions to help you prepare for your exams.

If you are not an AUS-e-TUTE member, you can access a "free-to-view" tutorial for evaluation purposes at http://www.ausetute.com.au/heatfood.html

Spud Lite?

"Spud Lite", the advertising poster said, "25% less carbs", followed in fine print by "than other potatoes".
"How strange", I thought, "I thought you ate potatoes for their carbohydrate (carbs) content so why would you want a potato with less carbohydrate?"
But then I started thinking about what this meant in terms of the chemical composition of the potato. If it contains 25% less carbohydrate, then surely that means something else must have been increased or added? Or are you just getting less potato for your money?

Typically, a traditional potato has the following approximate composition:

nutrient	% by mass
water	79
carbohydrate	17.5
protein	2
fat	0.1

 That is, 100 g of traditional potato contains about 79 g of water, 17.5 g of carbohydrate, 2 g of protein and 0.1 g of fat.

One way to reduce the percentage of carbohydrate in a potato would be to reduce the density of the potato.
If 100 g of a traditional potato had a volume of 92 mL, then the density of the potato would be 1.09 g/mL. 1 mL of traditional potato has a mass of 1.09 g and contains 17.5% by mass (0.19 g) of carbohydrate.
If "spud lite" has a lower density of potato "flesh", say 0.8 g/mL, then 1 mL of "spud lite" has a mass of 0.8 g and contains 17.5% by mass (0.14 g) of carbohydrate.
If we then compare equal volumes (sizes) of potatoes, say 1 mL of traditional potato and 1 mL of "spud lite" we find that "spud lite" contains 100 x (0.19 - 0.14)/0.19 = 26% less carbohydrate (by volume!).
But, if the density of "spud lite" is less, the % by mass composition remains the same, that is, for every 100 g of potato (traditional or "spud lite") there will be 17.5 g of carbohydrate (but the "spud lite" potato will be a bigger potato for your 100 g).

The nutrition label on a packet of "spud lite" potatoes gives the following masses per 100 g of potato:

• fat < 0.1 g
• protein 1.4 g
• carbohydrate: 8.9 g
• sugars: 1.1 g
• dietary fibre:  1.4 g

So, the total carbohydrate content is 8.9 + 1.1 + 1.4 = 11.4 g
(assuming the dietary fibre is cellulose which is also a carbohydrate).
This means that the actual mass of carbohydrate per 100 g of potato has been decreased. That is, "spud lites" are not just less dense than traditional potatoes.

 Another way to decrease the proportion of carbohydrate in your potatoes would be to increase their water content.
Imagine you have 100 g of traditional potato. This potato is made up of 79 g of water and 17.5 g of carbohydrate.
"Spud lite" contains 11.4 g of carbohydrate.

If all the lost mass of carbohydrate in the "spud lite" (17.5 - 11.4 = 6.1 g) was present as water, then the mass of water in "spud lite" = 6.1 + 79 = 85.1 g

And you, the consumer, is just paying for additional water in your potato!

Further Reading
 Experimental Design

 Carbohydrates
Proteins
Lipids (fats and oils) 
Percentage Composition
Density 

Suggested Study Questions:

1. Design an experiment to test the hypothesis that "spud lite" potatoes have a lower density than traditional potatoes.
2. Design an experiment to test the hypothesis that "spud lite" potatoes have a greater percentage by mass of water than traditional potatoes.
3.  For each serving of traditional potato given below, calculate the mass of carbohydrate consumed:
• 25 g of potato
• 75 g of potato
• 135 g of potato
4. Calculate the mass of "spud lite" you would have to consume in order to obtain
   • 1 g of carbohydrate
   • 7 g of carbohydrate
   • 21 g of carbohydrate
5. The density of potato changes as the potato ages on the shelf. The table below shows the results of an experiment in which the mass and volume of the same potato is measured and recorded every 3 days. Calculate the density of the potato on each day.

   Day	Mass (g)	volume (mL)
   1	142	130
   4	140	129
   7	138	128

6. Consider the results of the experiment above. Describe any trends that you see in the data and suggest reasons for these trends.
7. Explain what chemists mean when they refer to "carbohydrates".
8. The nutrition label on "spud lites" lists the mass of carbohydrate, sugars and dietary fibre separately. What do you think the "carbohydrate" is on this label?
9. Add together the percent by mass of all the components listed for a traditional potato.Suggest reasons for why the total percentage is less than 100%.
10. Potatoes are usually classified as high on the glycemic index (GI). What does this mean?

Fatty Acids

Do you want to answer any of the questions listed below:

• What is a fatty acid?
• What are the structures and formulae of common fatty acids?
• What is a saturated fatty acid?
• What is an unsaturated fatty acid?
• What is a monounsaturated fatty acid?
• What is a polyunsaturated fatty acid?
• What determines the melting point and solubility of a fatty acid?
• What is an essential fatty acid?
• What is an omega-3 fatty acid?
• What is an omega-6 fatty acid?

AUS-e-TUTE has new resources to help you answer these questions!
AUS-e-TUTE Members should log-in to use the new tutorial, game, test and exam.

If you are not an AUS-e-TUTE Member, a "free-to-view" Fatty Acids tutorial is currently available at http://www.ausetute.com.au/fattyacid.html for evaluation purposes.

Nano-zinc oxide and the Environment

Increasingly, we are making use of nanoparticles because of their unique properties compared to the same substance in bulk material. Many cosmetics, including sunscreens and sunblocks, now contain nanoparticles. When you go swimming or wash, these nanoparticles are washed off. Depending on where the nanoparticles are washed off, the waste water may directly enter a natural water system such as a river or ocean, it may end up in sewerage sludge, and it may eventually end up on land. What scientists do not know is just how many nanoparticles are entering the earth, air and water.

It is estimated that carbon nanotubes, which form part of a composite material in objects such as bicycle frames and tennis rackets, can take 10 years to breakdown and be released into the environment. On the other hand, about half of the cosmetic nanoparticles enter our waste water within one year.

Europe currently produces about 39,000 tons of nano-titanium dioxide per year, and it is estimated that the concentration of these nanoparticles in effected areas is now 61 micrograms per kilogram of ground. For humans, the maximum "safe" levels for exposure to these nanoparticles is set at:

• 2,500 mg/kg/day for oral exposure
• 2.4 mg/m³ for inhalation

While small amounts of zinc oxide are beneficial to plant growth, larger amounts can impair seed germination. Plants take up the free zinc ions in aqueous solution rather than the zinc oxide particles. This zinc becomes incorporated into the plants we eat. Zinc is an essential element in the human diet. The recommended dietary allowance of zinc for men is 11 mg/day, and for women is 8 mg/day. There are concerns that the increasing level of zinc in  plants may lead to accumulation of zinc in humans which will be detrimental to our health. Ingesting more than about 100 mg of zinc per day may lead to chronic toxicity.

Research into the environmental impact of nanoparticles, and their impact on plant and animal health, will continue for a long time.

Reference:
https://www.sciencedaily.com/releases/2016/05/160512084646.htm

Further reading
Nanotechnology: http://www.ausetute.com.au/nanotech.html
Graphene and Fullerenes: http://www.ausetute.com.au/graphene.html
Solutions Concepts: http://www.ausetute.com.au/solutions.html
Weight percent (w/w): http://www.ausetute.com.au/weightpc.html
Parts per MIllion (ppm): http://www.ausetute.com.au/partspm.html

Suggested Study Questions:

1. What is meant by the term "nanoparticle"?
2. If a nanoparticle of zinc oxide has a diameter of 20 nm, what is its diameter in:
   • metres
   • centimetres
   • millimetres
   • micrometres
3. Give an example of one property of bulk zinc oxide that is different to nanoparticles of zinc oxide.
4. Explain why zinc oxide nanoparticles are used in sunscreens.
5. What is a carbon nanotube?
6. Why are carbon nanotubes used in the production of bicycle frames?
7. Why are concentrations of titanium dioxide nanoparticles in soil given in units of micorgrams per kilogram of soil rather than in moles per litre?
8. Convert the following concentrations into parts per million (ppm)
   • 2,500 mg kg^-1
   • 2.4 mg m^-3
9. Using the recommended dietary allowance figures in the article, determine the mass in grams of zinc allowed for a:
   • 58 kg woman each day
   • 79 kg man each day
10. A typical vitamin pill contains 25 mg of zinc. By consuming 1 tablet per day, will the man or woman above exceed the recommended daily allowance of zinc?
11. 6 raw oysters contain 32 mg of zinc. How many oysters can the man and woman above eat before exceeding the recommended dietary allowance of zinc?
12. 85 g of cooked beef contains 7 mg of zinc. What mass of beef can the man and woman above ingest before exceeding the recommended dietary allowance of zinc.
13. 28 g of dry roasted cashews contain 1.6 mg of zinc. What mass of zinc, in grams, is present in 750 g bag of cashews?
14. 1/2 cup of cooked red kidney beans contain 0.9 mg of zinc. How many cups of red kidney beans would our man and woman above need to consume in order to achieve their recomended dietary allowance of zinc?
15. Do you think you should take a daily vitamin pill containing zinc? Justify your answer.

Hidden Salt in Food

Researchers at VicHealth and Deakin University compared how much salt people thought they consumed with how much salt they really had consumed and found that Australians were not only eating too much salt, but were also eating more salt than they thought they were!

Australians were found to be consuming between 8 and 10 grams of salt per day, about twice the amount recommended by the World Health Organisation (WHO) that recommends adults should eat less than 5 g of salt (a bit less than a teaspoon) per day. The "salt" they are referring to is "table salt" which has the chemical name "sodium chloride" and the chemical formula NaCl. Sodium chloride is actually an ionic substance made up of sodium ions (Na⁺) and chloride ions (Cl^-) in a ratio of 1:1 and it is the sodium ions (Na⁺) that are the cause for concern because elevated levels of sodium ions increase a person's risk of high blood pressure, heart disease and stroke. Unfortunately, non-Chemists often refer to this as elevated "sodium" levels rather than as elevated "sodium ion" levels.

If you want to reduce your sodium chloride intake, the first thing you can do is NOT add "table salt" to your food when you eat it. However, only about 20% w/w of our daily intake of sodium ions comes from adding sodium chloride to our food at the table before we eat it. The other 80%  w/w of the sodium ions we consume is already present in our food, either naturally or because it has been added during processing.

Natural sources of sodium ions in our food include:

• milk and cream: 50 mg of sodium ions per 100 g
• eggs: 80 mg of sodium ions per 100 g
• carrot: 69 mg of sodium ions per 100 g
• spinach: 79 mg of sodium ions per 100 g
• green beans, potatoes: 6 mg of sodium ions per 100 g
• pumpkin: 1 mg sodium ions per 100 g
• apple, banana, pear: 1 mg sodium ions per 100 g

By far the greatest source of sodium ions in our diet comes from eating processed foods:

• 1 slice of white bread (30 g) can contain 140 mg Na⁺
• 1 slice of cheddar cheese (20 g) can contain 140 mg Na⁺
• 1 foil pack of butter (7 g) can have 55 mg of Na⁺
• 1 small bowl of breakfast cereal (30 g) can have 140 mg of Na⁺
• 1 small packet of potato chips (45 g) can have about 300 mg of Na⁺
• 1 can (12 fl oz, about 350 mL) diet coke has 40 mg of Na⁺
• tap water contains about 20 mg Na⁺ per 1 L

Food you buy in packets from a supermarket will have a list of ingredients and you can read this to find the amount of sodium ions (Na⁺) present in the food.

However, there are many foods we buy that do not come in a packet which tells us how much sodium ion is present. These foods make up our "hidden salt intake". You may find this information on company websites, such as

• 1 McDonalds Big Mac contains 859 mg of Na⁺
• 6 KFC chicken nuggets with sauce has 1040 mg of Na⁺
• 1 slice (¹/₈ ^th) of medium pan Pizza Hut Meat Lover's pizza has 740 mg of Na⁺
• 1 Taco Bell black bean burrito contains 1030 mg of Na⁺

Many people forget that sodium ions are also present in many medicines. Effervescent medicines contain sodium hydrogen carbonate (or sodium bicarbonate) which helps them dissolve in water.
For example,:

• 1 effervescent Berocca tablet contains about 280 mg of Na⁺ while the film-coated Berocca tablet contains only 1.85 mg of Na⁺
• 1 Gaviscon Advance tablet contains 55 mg Na⁺ but 10 mL of liquid Gaviscon contains 141 mg of Na⁺
• 1 Panadol Actifast caplet contains 173 mg Na⁺ but 1 Panadol soluble tablet contains 428 mg of Na⁺

So, if you want a diet that's low in sodium, eat lots of fresh fruit and vegetables, drink lots of water, and avoid packaged food and "fast food", and, remember to choose "low sodium" medicines.

Reference:
http://www.abc.net.au/news/2016-03-24/reducing-salt-intake-could-save-thousands-of-lives-each-year/7274140

Further Reading:
Mass Conversions
Percent by Mass

Suggested Study Questions:

1. Convert the following masses in grams to masses in milligrams:
   • 5 g
   • 8 g
   • 10 g
   • 30 g
   • 100 g
2. Convert the following masses in milligrams to masses in grams:
• 1.85 mg
• 55 mg
• 69 mg
• 173 mg
• 859 mg
• 1040 mg
3. Calculate the percentage of sodium ions and the percentage of chloride ions in sodium chloride.
4. Use the information in the article to calculate the mass of sodium ions each adult Australian currently consumes as a result of :
   • adding table salt to food before eating it
   • table salt that is naturally present or is added to food during preparation
5. 100 g of milk contains 50 mg of Na⁺ . What is the percentage by mass of sodium in the milk?
6. One 30 g slice  of white bread contains 140 mg Na⁺. What is the percentage by mass of sodium in white bread?
7. For lunch, a student ate a sandwich made up of 2 slices of white bread, 2 foil packs of butter and a slice of cheddar cheese. She also ate a 200 g banana, and washed it all down with 250 mL of plain, unflavoured milk.
   • Calculate the mass of sodium ions the student consumed for lunch.
   • Calculate her consumption of sodium ions as a percentage of the WHO recommended daily intake of sodium ions.
8. A different student consumed a Big Mac, 1 can of diet coke, and a 200 g packet of potato chips.
• Calculate the mass of sodium ions the student consumed for lunch.
• Calculate her consumption of sodium ions as a percentage of the WHO recommended daily intake of sodium ions.
9. For her birthday, a Chemistry Teacher's class gave her a 500 g block of dairy milk chocolate. The label included the information that the block of chocolate contained 82 mg of sodium per 100 g.
   • What is the mass of sodium ions in the block of chocolate?
   • If each person in the class of 22 received an equal share of the block chocolate, what mass of sodium ions would each person consume?
10. In Australia, the maximum recommended dose of paracetamol (the active ingredient in panadol tablets) is 4000 mg per day. 1 soluble Panadol tablet contains 500 mg of paracetamol.
    • What is the maximum number of soluble Panadol tablets per day that an adult Australian should consume?
    • If an adult Australian consumed the maximum recommended dose of soluble panadol tablets in 1 day, what mass of sodium ions would they have consumed?
    • What percentage of the WHO recommended maximum intake of sodium would this amount of panadol be?

Salivary Amylase

Wheat, potatoes, corn and rice contain starch and starch is a major component of the modern diet. Amylase enzymes secreted in saliva help break down starches into simple sugar molecules that can be absorbed into the bloodstream, influencing blood glucose levels.
Monell Center scientists have undertaken a study which revealed that changes of starch consistency in the mouth were directly related to salivary amylase activity. In this study:

• saliva was collected from 73 subjects
• saliva was mixed with a standardized starch solution, and a sensor measured the enzymatic break-down of the starch's consistency
• enzyme and protein assays directly measured the amount and activity of salivary amylase in the saliva samples
• subjects completed a survey to rate the perceived breakdown of a starch sample in the mouth over a minute

Foods with different starch levels were perceived differently by people depending on how much salivary amylase they produce. "What may seem like a thick and resistant pudding or starchy food to some may seem noticeably thin in the mouths of others", said Monell sensory geneticist Paul A. S. Breslin.
Individuals who have more salivary amylase may break down starchy foods more quickly, leading to more rapid increase of post-meal blood glucose levels. It is possible that high levels of salivary amylase contribute to the risk of insulin resistance and non-insulin dependent diabetes.

Reference:
Abigail L Mandel, Catherine Peyrot des Gachons, Kimberly L Plank, Suzanne Alarcon, Paul A S Breslin. Individual Differences in AMY1 Gene Copy Number, Salivary α-Amylase Levels, and the Perception of Oral Starch. PLoS ONE, 2010; DOI: 10.1371/journal.pone.0013352

Further Reading
http://www.ausetute.com.au/enzymes.html
http://www.ausetute.com.au/sugars.html

Study Questions

1. Give a general chemical formula for starch.
2. Starch is an example of a biological polymer. Of what monomers is this polymer made up of?
3. Another biological polymer is made up of the same monomers as that of starch, but, it is found in animals instead of plants. What is the name of this polymer?
4. Assuming you were given two sample bottles, one contained the plant polymer starch, and the other contained the animal polymer in question 3. What simple test or tests could you perform to identify which bottle contained the plant polymer and which contained the animal polymer?
5. What is meant by the term enzyme?
6. Draw a diagram to represent how amylase acts on starch to produce simple sugars.
7. Assume one of the subjects in the study had a fever and was found to have a temperature of 40^oC. What effect would this have on the results obtained during the survey phase of the study?
8. Imagine a well-wisher gave our sick subject above a "nice, hot lemon drink" to relieve the fever's symptons just before the saliva sample was collected. What impact would the lemon drink most likely have on the level of amylase activity?