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.