Wednesday, December 29, 2010

In time for New Years!

The science of drinking bubbly

A new study in the Journal of Agriculture and Food Chemistry confirms what a lot of us already knew - the glass, the way you pour and the temperature is all important to the taste of Champagne:

J Agri Food Chem 2010, 58, 8768-8775

The analysis in the Journal of Agricultural and Food Chemistry uses fast photography, infrared light, diffusion coefficients and a lot of equations with Greek letters to measure what happens to bubbles with different pouring methods.

Skipping the equations, it turns out that pouring gently down the side of a glass preserves about twice as much carbon dioxide (bubbles) as pouring straight down to the bottom of the glass.

But that wasn't all: The shape of the glass also matters. Tall "flutes" preserve bubbles far better than the wide, shallow glasses sometimes used in North America.

And bubbles stay longer if the champagne is really cold — which affects both the density of the wine (cold is more dense) and its surface tension.
Read more:


On the Losses of Dissolved CO2 during Champagne Serving

Grard Liger-Belair, Marielle Bourget, Sandra Villaume, Philippe Jeandet, Herv Pron, Guillaume Polidori
Journal of Agricultural and Food Chemistry 2010 58 (15), 8768-8775

Friday, December 17, 2010

Tenderizing meat with kiwi juice

I read somewhere that Kiwi juice can tenderize meat.

So, of course, I did an experiment!

I took two beef fast-fry steaks and marinated one in crushed kiwi and the other in some soy sauce and vinegar ('cause I like that marinade)

I let the meat marinade for a couple of hours - although some recipes say that might be too long.

The steak in the kiwi marinade felt a lot floppier than the soy sauce marinade:
I fried up some onions and garlic in olive oil and then placed the steaks in the pan.  I used a trick I had recently seen on a cooking show - to brown the meat well, since fast-fry steaks often curl a bit in the pan, fill a pot half full with water and place it on top of the steaks to press them down. Choose a pot that is slightly smaller at the base than the frying pan so most of the meat is covered.  The increased contact with the bottom of the pan will brown the meat better.  Leave it for a few minutes and then turn the meat.  I just threw in the marinade from both the steaks so the gravy it produced was both sweet, salty and tart - a lovely combo.  Served with egg noodles it was delicious.

I had cut each steak in half and served my son and I one of each marinade for the taste test.  The verdict was that the kiwi marinade was a bit more tender (although with fast-fry steaks it is a bit hard to differentiate) but we liked the marinade of the soysauce better - need to work on adding other flavours to the kiwi marinade. But the gravy I made with the pan drippings were delicious!

So why did the meat tenderize more?

Turns out that kiwis, pineapples, mango and papaya contain an enzyme that will break down the protein in meats.  The enzyme, actinidin, is called a protease enzyme.  Enzymes are very large molecules - so large that scientists need a shorthand to describe them - they make them look like ribbons:

Sequence - each letter represents part of the molecule and the squiggles and arrows indicate how the molecule folds and twists
Parts of the enzyme react with the proteins to break the bonds which degrade the cellular structure of the meat.
"protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein."
One protein involved is Actin (which is involved with the muscular tissues)
From Wikicommons:

As you can see proteins and enzymes are similar since they are both macromolecules.  The actinidine reacts with the amino acid parts of the protein to break the big chains and therefore break down the strength of the muscle meat and tenderize it...

By the way, our bodies also contain proteases such as pepsin and serine to help us break down and digest the rest of the protein we eat.

Addendum (Sept 7, 2011): Just found this M.Sc.(Food Science) thesis by Jin Han on tenderizing lamb with kiwi juice:

Friday, December 10, 2010

I need these!!

Cool stocking stuffers for the chemistry cooks in your list!
Cookie cutters of test tubes and beakers!

Photo from Science lab cookie cutters

And to make the cool icing designs here is a wonderful blog with a great recipe for royal icing (the icing that gets really hard) and "flood"icing to fill in the colours:

Tuesday, December 7, 2010

Lemon-honey dressing and handedness

My son "invented" a very simple salad dressing with two ingredients, lemon juice and honey.  I put the invented in quotes since a simple internet search reveals a number of recipes for this already: Jamie Oliver, Great Grub,  and even Martha Stewart.  Many of these add extra ingredients - olive oil, pepper, herbs and spices.  My son's was pure - lemon juice and honey...
I actually like his recipe on one of my favourite salads.  It is a mix of romaine lettuce sliced finely, chopped apple, chopped avocado, green or red peppers, and raisins (and sometimes pomegranate)

The dressing makes the salad very light and refreshing!

Limonene is the chemical that makes oranges and lemons smell so lovely - but it is also the piney smell of can this be?

Well, limonene is actually what is called a chiral chemical - it has two forms with almost the same structure:
The D-limonene (also called R-limonene) is the chemical found in the skins of oranges and lemons and has been produced in about 95% purity from the waste of orange juice production for many years!

The L-limonene ( or S-limonene) has been extracted purely from turpentine and from the plant Eucalyptus Stageriana. Some is present in the skins of oranges and lemons too.  

The R and S refer to the "handedness" of the molecules. Your right and left hands are chiral - they are un-superimposable mirror images.  R comes from the latin Rectus and S from the latin Sinister - right and left.

Chiral compounds often are very similar in properties to each other but sometimes exhibit quite different properties.  R- and S-limonene have this effect - R-limonene is orangey smelling while the S version is more lemony smelling.  The same is true for a related chiral molecule: R- and S-carvone.
R-carvone has the odor of spearmint and the S-carvone is the smell of caraway!


Theodore J. Leitereg, Dante G. Guadagni, Jean. Harris, Thomas R. Mon, Roy. Teranishi (1971) Chemical and sensory data supporting the difference between the odors of the enantiomeric carvones. Journal of Agricultural and Food Chemistry, 19 (4), pp 785–787 DOI: 10.1021/jf60176a035
L. Friedman & J.G. Miller, Odor incongruity and chirality, Science, 172, 1044-6 (1971)

David J. Willock (2008) Molecular symmetry, 

pg 41

A.F. Thomas and Y. Bessiere (1989) Natural Product Reports, 6291.
DOI: 10.1039/NP9890600291

Thursday, December 2, 2010

More good links to information

I'll put these on the side bar eventually too!

There is a new blog from the Royal Society of Chemistry that is highlighting the content of its newest journal, Food and Function.

This is the blurb about the new journal:
Food & Function is a new monthly peer-reviewed journal which provides a unique venue to publish work at the interface of the chemistry, physics and biology of food.

ScopeThe journal focuses on the interaction of food components with the human body, including:
  • The physical properties and structure of food
  • The chemistry of food components
  • The biochemical and physiological actions
  • Nutrition and health aspects of food  
Topics covered in the journal include, but are not limited to:
  • The chemistry and physics of food digestion processes
  • The relationship between the physical properties/structure of food and nutrition and health e.g. nutrient release and uptake
  • Molecular properties and physiological effects of food components (novel ingredients, food substitutes, phytochemicals, bioactives, allergens, flavours and fragrances)
  • Efficacy and mechanisms of bioactives in the body - including biomarkers
  • Effects of food contaminants - including toxicology and metabolism
  • Nutrient physiology/metabolism and interactions
  • The role of nutrition and diet in disease   
It won't be an easy read for the non-scientist home cook but I'll try to glean some gems out of it for you!

The blog should be a bit more accessible.

Monday, November 29, 2010

free webinar with two top foodie scientists

On Wed Dec 9 there is a free webinar sponsored by the American Chemical Society and hosted by two leading molecular gastronomy gurus, Peter Barham, author of "The Science of Cooking", and Shirley Corriher, author of CookWise and BakeWise.  

Just go to this link and register to get the details:

Hear you there!

Addendum (Dec 10, 2010) : If you missed the webinar, you can still listen to the recorded session at the same link - also there are some awesome sounding recipes listed as well.

Product ingredients labels - sugars

We have all heard the sensational headlines about this or that additive to food that is suddenly thought to be unhealthy or the latest magic bullet!  I thought I would include an occasional set of posts on some of the ingredients that are in the processed foods we buy.  I'll try to explain simply why they are added and if necessary link to some studies about their health effects (although remember everything is hazardous to your health if taken in too large a quantity - even water*)

Since I recently posted on making brittle, I will briefly discuss sugars.

Many food products have either sugar, glucose or fructose as added ingredients.  Sucrose is often made from sugar cane or sugar beets and is the most commonly found ingredient in soft drinks and foods.
Fructose is the sugar produced by fruits and lactose is the sugar found in milk.

Sucrose and lactose have similar structures as do glucose and fructose.

Sucrose and lactose (as well as many starches) are broken down into glucose in our digestive tract. We need a steady level of glucose to remain healthy - the body produces insulin to control the amount of glucose - extra glucose is turned into fat which can be changed back to glucose when needed.  Diabetics have problems producing insulin in their livers and end up with too much glucose in their bloodstream which makes them hyperglycemic.  They need to either very strictly control their intake of sugars and starches and/or take insulin to make up for what their body is not producing.

A healthy body balances our sugar intake with insulin production - and if we eat too much sugar (my bad..) we create fat!

We eat via food and drink tremendous amounts of sugar - sugar is added to almost everything since it tastes so good!
One hundred and fifty-six pounds. That's how much added sugar Americans consume each year on a per capita basis, according to the U.S. Department of Agriculture (USDA). Imagine it: 31 five-pound bags for each of us.
That's not to say that we get most of the sugar in our diets directly from the sugar bowl. Only about 29 pounds of it comes as traditional sugar, or sucrose, according to The Sugar Association, a trade group of sugar manufacturers. The rest comes from foods.
Of course, those foods include things like candy, soda, and junk food. But plenty of sugar is hiding in places where you might not expect it.
Some types of crackers, yogurt, ketchup, and peanut butter, for instance, are loaded with sugar -- often in the form of high-fructose corn syrup, or HFCS. Use of this sweetener has increased 3.5% per year in the last decade, according to the World Health Organization (WHO). That's twice the rate at which the use of refined sugar has grown.   
A 12 ounce (355 mls) bottle of soda has typically 35-39 grams of sugar!  Would you sit down and eat 7 teaspoons of sugar?  But you would drink a can of Coke (actually I don't - I find it way too sweet!) but even one of my favourites is root beer and it is just as sweet.  Fruit juices are not much better even when they are pure juice (with no added sugar) - the fruit just contains fructose instead of sucrose.
Here is a video that shows just how much sugar this really is:

So read the labels!

* Disclaimer: the link is a hoax - dihydrogen monoxide = water H2O


Tuesday, November 23, 2010

Vegetables and pH of water

Addendum Nov. 2, 2011:  Here is another good set of experiments and explanation on keeping greens green!:

The pH of the water you cook with can affect the quality of the final boiled vegetables (baking or stir-frying do not count here since the vegetables are not surrounded by water) I have noticed this most in the leafy greens (eg. kale and collards) and other green veggies. Kale's vibrant green colour can be preserved better if you add a tiny bit of vinegar to the cooking water especially near the end. 

The cell walls and membranes of vegetables contain proteins, cellulose, hemicelluloses and pectins.
During cooking some of the proteins are denatured by heat and the celluloses and pectins are lost based on the pH of the water – the hemicelluloses are dissolved by basic water and the pectins by more acidic water. 

Denatured and reformed proteins
from: Geoffrey Cooper, The Cell - The Molecular Approach, 2nd ed, p.

 Pectins aid in giving fruit and veggies solidity – loss of pectin makes them mushy. We use pectin in jam making to create the gell (i nearly spelt that "Jell" - the omnipresence of brand names..) – it does the same thing within the plant cells. 

Cellulose is not easily dissolved – it is a one of the basic building blocks of plants and not digestible by our stomachs (excellent source of fibre though!) - it is a chain of sugar molecules but because of the way it is formed it is very resistant to being broken down by chemicals.
The hemicelluloses and pectins also form parts of the cell walls and they can be dissolved so their loss will make the veggies softer.

Experiment 1:
Cooked green beans in salt water (left) and acidic water - added vinegar (right) for the exact same length of time.
 The beans cooked in the acidic water lost their colour significantly and tasted vinegary (probably used too much vinegar!)

Experiment 2:
Cooked sugar snap beans in salt water (1/2 tsp), baking soda water (1/2 tsp) and vinegar water (1 tsp)

acidic water
the sugar snap beans retained their colour and crispness without colouring the water

basic water
still crisp but outer skin a bit slimy  - flavour still good - water was quite green (removal of vitamins

salt water
colour retained - flavour good - water coloured like the basic water (salt is a bit basic too)

So if you want to keep the veggies crisp add a little bit of vinegar to the water - seems to also help retain the colour and therefore probably the vitamins - although heating any food will break down the vitamins to a certain extent so there is always loss.

Another idea to explore later - do we traditionally use a vinegar based dressing on salads to aid the digestion in addition to tasting really nice??

Harold Mcgee 1984. On Food and Cooking, p.147-180.

Monday, November 22, 2010

From sugar to brittle and back?

I tried to make almond brittle using maple syrup instead of corn syrup - I ended up making maple tasting sugar crystals... what did I do wrong in hindsight?

           From this to this!

Normally in making brittle type candies it seems all you need to do is to melt sugar and create a liquid that then hardens like a glass.  Here is an example from

Mom's best Peanut Brittle

1 cup white sugar
1/2 cup light corn syrup
1/4 teaspoon salt
1/4 cup water
1 cup peanuts
2 tablespoons butter, softened
1 teaspoon baking soda

  1. Grease a large cookie sheet. Set aside. [or you can use parchment paper instead]
  2. In a heavy 2 quart saucepan, over medium hear, bring to a boil sugar, corn syrup, salt and water. Stir until sugar is dissolved. Stir in peanuts. Set candy thermometer in place and continue stirring. Stir frequently until the temperature reaches 300 degrees F (150 degrees C), or until a small amount of mixture dropped into very cold water separates into hard and brittle threads.
  3. Remove from heat;  immediately stir in butter and baking soda; pour at once onto cookie sheet. with 2 forks, lift and pull peanut mixture into  rectangle about 14x12 inches; cool. Snap candy into pieces.
All rights reserved copyright 2010

This recipe works beautifully so why did my simple substitution of the maple syrup end up crystallizing instead of staying glassy?

Turns out that corn syrup and maple syrup are actually quite different not only in taste.  Corn syrup is mainly glucose and maple syrup is mainly sucrose (as is plain white sugar)  The addition of the corn syrup to the brittle recipe is to interrupt the reformation of sugar crystals at the high temperatures when the mixture is supersaturated. We want the supersaturation to create the glassy liquid but, in a pure sucrose mixture at high heat, any crystal that is in the pot can create a rapid crystallization of the whole mixture which is what happened in my case!

As I researched a bit more I discovered that most brittle recipes that use maple syrup also add some butter at the beginning as this will also help prevent the crystallization from occurring by keeping the sugar molecules separated by minute amounts of oil.

So I redid my experiment: I took the recrystallized sugars, blended them until they were small crystals again and remelted them - this time with 2 tablespoons of butter added immediately.  Panic set in at the 250 degree mark as it looked like it was going to crystallize again (Sidenote: Use a silicon or very sooth spatula to stir; not a wooden spoon as there are many more crystallization sites on a rough surface!) but I kept stirring and finally it stayed melted at about 300 degrees (hard crack).  I added some roasted almonds and poured the mixture onto a baking tray covered in parchment paper. The colour was much darker since it had been double-heated but it tastes yummy!

Here is a proper maple sugar brittle recipe
Maple Walnut Brittle

1/4 cup real maple syrup
1 cup granulated sugar
1 cup butter
1/4 cup water
2 cups toasted walnut pieces

In heavy bottomed saucepan, over medium heat, stir together syrup, sugar, butter and water until melted and creamy. Continue to gently boil and do not stir until candy thermometer reaches 300°F (150°) “hard crack”. Immediately stir in walnuts and carefully pour hot mixture onto an ungreased cookie sheet and spread out to a thin layer with a wooden spoon. Cool completely.

Break into large pieces and store in an airtight container. 

Makes 1 pound.

Recipe provided courtesy of the American Heart Association.

Added references
For more maple sugar info:
Maple fact sheet 202
Ochef - Using Sugar, Brown Sugar, Honey, & Maple Syrup Interchangeably
And a quick scientific overview of how the sugars differ in making candy:

Saturday, November 13, 2010

Baking Soda vs Baking Powder

I've had these two boxes as staples in my baking supplies forever as do most of homes. We follow the instructions to use one or the other (or both) in our recipes but do we know why?

I knew that baking soda makes great volcanoes when mixed with vinegar but why do some recipes use baking soda and some baking powder?

I read that the same ingredient, sodium bicarbonate, is in both but there is something more in baking powder. I did some experiments (as all ex-chemistry students like to do – or is it just me?)

I added a tablespoon (or 15 mls) of baking soda to a glass (left) and did the same with the baking powder (right).

Then I added about 50 mls (¼ cup) of water to each. I did not see much difference except the baking soda had larger clear bubbles than the baking powder but not much more action.

Then I tried the same experiment with vinegar! Wow!
The baking soda erupted! The baking powder did bubble a bit but very little in comparison.

Next, I decided to do a simple baking experiment – biscuits. The recipe normally uses baking powder.

Basic biscuits*

Preheat oven to 425°F
Sift together
2 cups flour
3 teaspon baking powder
½ teaspoon salt
Cut in
¼ cup shortening
Add all at once, stirring until soft ball is formed:
¾ cup milk
Turn dough onto floured board, knead lightly 20-25 times. Roll or pat dough ½ inch thick. Cut with floured biscuit cutter or glass. Place on ungreased baking sgheet and bake 10-12 minutes. Serve hot. Makes 18-20.

*Doris Janzen Longacre, More-with-Less Cookbook, Scottsdale: Herald Press, 1976, p.72

Now a scientific experiment includes experimental details (a recipe) and the parameters (ingredients) are changed to determine how the results will differ.
I followed the recipe above exactly for the one batch of biscuits and just substituted baking soda for the baking powder in the the second batch and used a double-acting baking soda in the third batch.

 Now an comparative experiment must have the exact same conditions for all batches so I put all the biscuits on the same cookie sheet for the oven.

Then I baked the three batches to see what the small change in ingredients made to the final product.

Wow! Quite the difference! The baking soda biscuits look wonderful but actually tasted quite bitter. The paler golden biscuits in the middle tasted the way biscuits should taste and the double acting ones were a bit taller and more speckled and tasted very similar to the baking powder ones but a tiny bit bitterer.

So why the variety? Baking soda is pure sodium bicarbonate which is a chemical base and needs the addition of an acid to create a reaction.

Sodium bicarbonate
(IUPAC name: Sodium hydrogen carbonate)

The original test with the vinegar results in the following reaction:

NaHCO3 + CH3COOH → CH3COONa + H2O + CO2(g)

You can see that the mixture of the sodium bicarbonate, NaHCO3, and acetic acid, CH3COOH, creates sodium acetate and water and carbon dioxide - it is the carbon dioxide that creates  the explosion of bubbles!

So recipes using baking soda alone also must include something like buttermilk to play the role of the acid in the reaction above.  The milk in the biscuits reacted with some of the sodium bicarbonate but not all of it so the biscuits were bitter which is the natural taste of the baking soda.

The first baking powder I used contains sodium acid pyrophosphate, sodium bicarbonate, corn starch, and mono calcium phosphate.

Sodium acid pyrophosphate
(IUPAC name: Disodium dihydrogen diphosphate)

Monocalcium phosphate
(IUPAC name: Calcium dihydrogen phosphate)

Calcium dihydrogen phosphate is also used in the food industry as a leavening agent to cause baked goods to rise. Because it is acidic, when combined with an alkali ingredient – commonly sodium bicarbonate (baking soda) or potassium bicarbonate – it reacts to produce carbon dioxide and a salt. The carbon dioxide gas is what leavens the baked good. When combined in a ready-made baking powder, the acid and alkali ingredients are included in the right proportions such that they will exactly neutralize each other and not significantly affect the overall pH of the product.

The double action baking powder contains corn starch, sodium bicarbonate, sodium aluminum sulphate and acid calcium phosphate (mono calcium phosphate by another name).
The main use for SODIUM ALUMINUM PHOSPHATE, is as a leavening agent or acid for mixing baking powders, this is a new product in the baking industry. The SODIUM ALUMINUM PHOSPHATE, has a different performance profile than other leavening agents; it reacts slowly with the Sodium Bicarbonate in the mixing stage, there is only a 20 to 30 % Carbon Dioxide delivery from available. The difference is released during the oven stage.

This reaction is:
NaAl(SO4)2 + 3 NaHCO3 ----> Al(OH)3 + 2 Na2SO4 + 3 CO2 

Finally, the thermal decomposition  reaction of sodium bicarbonate is:
2 NaHCO3 → Na2CO3 + H2O + CO2
So even in the oven, any unreacted baking soda will continue to produce carbon dioxide in smaller amounts.

So basically you need both the acid and the base to create the optimum reaction in any of the variations!

TLC Cooking: What is baking powder, and how does it work?

Monday, October 4, 2010

Cooking = Chemistry

All cooking is really science: recipes are the experimental details, pots and pans are the beakers and test tubes, measuring spoons and cups are the volumetric flasks and pipettes, and the stove is the bunsen burner...

So what is actually scientifically happening when we cook and bake? I will attempt to introduce you to some great recipes and to some of the reactions that occur during the process.

Why would you want to know this (I know you probably hated high school chemistry)? Because it can make your food taste better if you know why/how the frying, baking and mixing works!

Please send me feedback and questions you may have!