Monday, 25 July 2011

Who said drinks and science don't mix?

The culinary arts have long been intertwined with science, something that has become more prevalent in the food & beverage industry with the likes of Ferran Adria, Heston Blumenthal, Harold McGee, Eben Freeman, Tristan Stephenson and Tony Conigliaro notably revered for their outstanding work.

At the weekend I worked some bartending shifts at one of my consultancies, Mim in Aberdeen, and found myself puzzled by the difference between two drinks that were practically identical save for the fact one was alcoholic and the other non-alcoholic.

A guest at the bar ordered two Mediterranean Fizzes, a cocktail on the menu that is available as both an alcoholic and non-alcoholic beverage, requesting both variants.

Mediterranean Fizz

50ml Ciroc Vodka
6 White grapes
6-8 Basil leaves
25ml Fresh lemon juice
20ml Vanilla sugar syrup
Top with soda water

Method: Muddle grapes in mixing glass to extract all juice. Add remaining ingredients other than soda and fill with cubed ice. Shake until ice cold, fine strain, and top with soda water.
Glass: Collins/Highball
Garnish: Basil leaf
Ice: Cubed

At the point of serving I noticed that the non-alcoholic variant had taken on a considerably darker colour of green compared to the drink with alcohol. I tried both to ensure I'd made them right and found no problem whatsoever and didn't really think any more of it. Luckily these guests ordered the same round a further three times and on each occasion I found the colour to be exactly the same, darker for the non-alcoholic drink, lighter for the alcoholic version

Over the last couple of days I'd thought about it some more and it also reminded me of something I learnt in Germany last year about Joerg Meyer's Gin Basil Smash (pictured above) and the way they prepare it at Le Lion. Joerg discovered that shaking this drink with metal-on-metal tins versus metal-on-glass made for a darker green beverage. As far as I'm aware he still doesn't know why.

I posted the following question;

"When preparing two Mediterranean Fizzes at the same time (1 alc and 1 non-alc) the non-alc cocktail was always greener in colour. Same number of leaves/amount of liquid in both, so why was it greener? What was the non-alc 'extracting' that the alc wasn't?"

on Twitter this afternoon which piqued the interest of Tristan Stephenson and Scott Spolverino.

Our discussion covered a number of potential explanations with the likely conclusion that ethanol is a better solvent than water so the chloropyll (the pigment that gives basil its green colour) is soluble in alcohol. Now I'm no scientist but that makes perfect sense to me, however where the colour goes doesn't? I'm hoping someone can explain...

Just as we had seemed to hit upon an explanation Tristan raised the rather good point that the increased opacity of extra lemon juice and syrup added to the non-alc Mediterranean Fizz possibly made for what looked like a darker drink. Back to square one and in need of (a liquid) lunch, I decided to construct an experiment using Tristan's suggested method of water in place of gin in the non-alcoholic drink. I hoped this would give me some clarity to the green issue...

As chlorophyll is present in nearly all plant-life, and I had a box of freshly-picked mint leaves in my fridge, I opted to make a Southside to see if the results were the same as the Mediterranean Fizzes from Saturday. I tried to make the drinks identical barring the base (gin and water) but in no way do I profess to be a scientist so if there's something amiss please let me know and don't shout me down for my poor scientific methodology!

Alcoholic Southside

50ml Tanqueray Gin
25ml Fresh Lemon Juice
20ml Sugar Syrup
15 Small mint leaves

Non-alcoholic Southside

50ml Water
25ml Fresh Lemon Juice
20ml Sugar Syrup
15 Small mint leaves

Variables I took into consideration:

- All ingredients were added to a metal shaker before being filled with 200g of ice
- All ingredients were measured and/or weighed
- Both were shaken in a Boston (metal-on-glass)
- Both drinks were shaken for 10 seconds simultaneously (left hand and right hand) before being fine-strained.
- The lemon juice was squeezed from the same fruit
- The sugar syrup came from the same bottle
- The ice came from the same bag and almost every cube was the same size

Here is a picture taken immediately afterward. The alcoholic Southside is on the left...

As you'll see the result was exactly the same, for whatever reason the alcoholic version is lighter in colour which I find fascinating. Some will likely think I'm crazy but it's an interesting consideration for anyone who creates cocktails as colour plays a huge part on an individual's perception of a drink. Having the knowledge to anticipate the colour when mixing alcohol with herbs would be useful to know whether it be for bitters, liqueurs or in a cocktail.

Anyway, I'm passing this over to the many scientists out there who may be able to give me a definitive explanation to what is making the colour difference between the alcoholic and non-alcoholic variants?!? And just what is happening in Joerg's metal-on-metal tins? I'm sure he'd appreciate an answer as well...


Adam Elmegirab
Bar Consultant / Compounder
Evo-lution / Dr. Adam Elmegirab's Bitters

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  1. If you want to have a Gin Basil Smash REALLY GREEN you have to muddle one the Basil, nothing else, DRY and Hard in the Shaker...

  2. Thought this was to do with alcohol extracting the chlorophyll and making it chemically available for acidic oxidation by the citrus (vs. just held in suspension with water), but then tried the same experiment with water & mint against vodka & mint and got the same result - so that wasn't it. Good excuse for more playing around though.

    Also tried coffee filter paper on both to ensure no bits, but water still much greener than vodka.

  3. Fun research project Adam. This is my best guess for your green observations. Chlorophyll contains a porphyrin ring which binds magnesium and is the location of light absorption and thus the green color. (Chlorophyll absorbs red and blue light and we see green). Chlorophyll is not soluble in water, therefore the porphyrin ring remains intact and absorbing light. Your non-alcohol drink is greener, right?

    Chlorophyll is soluble in alcohol. The alcohol disrupts the porphyrin ring causing the loss of magnesium, and thus mucks up the light absorption and diminishes the green color that we see. Therefore, Southside with alcohol is less green.

    Really enjoy the blog. Thanks,

  4. Libationlaboratory's comment makes a whole hell of a lot of sense. This would explain the tendency of the metal on metal shook cocktail to be greener than metal on glass. The ethanol would cause the disruption of the porphyrin ring, dropping a magnesium ion but the activity of the ring could, in theory, pull Aluminum ions (from an aluminum shaker) or chromium ions (from a stainless steel shaker) out of the shaker and bind it to the same place. The increased surface area of metal on metal gives more activation sites for the reaction to take place.

    Science + booze = fun.

  5. Nothing to add scientifically-speaking I'm afraid but this sort of meekness is totally up my street, more of the same please!

  6. Hey Scott- What about iron? I'm more inclined to think that chlorophyll's porphyrin ring would coordinate iron in place of the magnesium, than to pick up a chromium. I'm guessing that Joerg used a stainless steel shaker, making iron abundantly available. It would be interesting to see if an aluminum shaker had the same effect. Just a thought...

  7. Iron's a possibility. I just kinda assumed that it would pick up the chromium first as that's the purpose of chromium in stainless steel: to react instead of the iron and prevent iron oxidation / rust. But iron is possible. I'd imagine that it would be a higher concentration of iron ions binding to the porphyrin ring in older shakers / heavily used shakers as opposed to new shakers. But I'm not entirely sure what the chemical activity of chromium vs. iron is.

  8. I enjoyed reading your work. I'll come back for more

    Keep up the good work :) from TheStillery, a stuart bar in Florida