Protein Shakes: the science behind making the perfect foam on your cocktail.

In certain cocktails, a foam can be the essential ingredient that turns an otherwise flat and uninteresting drink into a textured and complex tipple, a light and fluffy introduction onto your palate of the flavors waiting underneath, the gentle kiss before the punch as it were. What would a Clover Club be without that silky sensation, the density of weight giving way to the well-chilled drink beneath, giving a luxurious texture to what could otherwise be an unremarkable drink?

But how and why do these layers form? The answer is protein; egg whites are around 92% water, and 8% protein, tightly bonded spirals that contain amino acids. By emulsifying an egg white via whisking or dry-shaking, you break this protein shell and expose the amino acids, some of which are hydrophillic and some of which are hydrophobic, that is, some are attracted to water and some are repelled by it. 

As such, the rapid agitation introduced by your emulsification causes the hydrophillic amino acids to gather close to water, and the hydrophobic ones to gather  close to the air introduced into the mix. This causes the protein strands to unfold and bond to other adjacent proteins, forming a network of bonds that make up the body of the foam.

The more you emulsify the stiffer the foam will get until all the proteins have unfurled. In a solution (say, a cocktail for example), the linked proteins will rise to the surface of the drink due to the air bubbles being lighter than the liquid surrounding it. Protein will continue to bond with adjacent protein, so after 30 seconds there will be a layered separation of liquid and bonded proteins, i.e. the foam.

Simple, right? Well not so much. Egg white isn't the only ingredient in your drink that can contain the combination of protein and acids that can create a foam, and there are myriad reasons that can lead to your foam being too thin, dissolving too quickly, or just looking sad and flaccid.

The higher the alcohol content in the cocktail, the lower the ratio of bonds formed so less foam; this will also create weaker bonds that will break apart much quicker than in a solution with lower alcohol.

Likewise, the ratios of sugar and acid in the solution will affect how well your bubbles form - consider the drink as you would consider a delicate meringue; sugar acts as a stabiliser while emulsifying, creating stronger, but smaller bonds. The higher the sugar content, the denser the foam will be. Acidity is another variable - if a solution is too acidic then bonds will begin to weaken and collapse very quickly after settling, leaving you with a deflated and unpleasant looking foam.

Another factor is the freshness and temperature of the egg white used in the recipe.  Refrigerated whites will be slow to emulsify, taking much longer than with room temperature whites, and the ideal age of an egg will be 2-3 days after laying. Eggs that are too fresh will produce a white that visibly separates when cracked: a thin, watery liquid will separate from the jelly-like inner white, known as the ovomucin. Ovomucin acts as a trypsin inhibitor, trypsin being a enzyme that breaks down proteins and occurs naturally in digestion and is present in the egg when it is laid.

The older an egg is the weaker the proteins become as the ovomucin degrades and the trypsin starts to break down the proteins in the albumen, and the weaker and thinner the resultant foam will appear. For long term storage pasteurisation works as a solution to denaturalise the enzymes in egg white, however the egg white can still spoil for bacterial reasons.

An ideal solution for any high-volume usage of egg white would be the use of dehydrated albumen, as it takes up less space, does not spoil in it's dry form and is consistent in it's protein content across a batch - eggs are of course, at the end of the day an organic product and never consistent from egg to egg. Just place egg white in a shallow pan and put it into a dehydrator (under 65c, or else you'll end up with a large omelette) and blend it once dried - store somewhere dry.

A bar spoon per drink is about perfect, and just dry shake and wet shake as you would using egg white. The only thing you have to adjust for using this method is the liquid volume you are losing without hydrated egg white - remember your wash lines before spinning this method out.

It goes without saying but of course you shouldn't be using cage eggs - poor nutrition in the chickens mean a low protein count and a watery egg white and a poor foam. Also it's incredibly cruel.

Egg white isn't suitable for every drinker however, as people with dietary concerns or squeamish individuals shy away from a drink when they see egg white going into the mix. Therefore it is worth investigating other options to create the same affect in a cocktail.

One such option is pineapple juice - pineapple has a high level of protein and creates a thick, foamy head when emulsified as a result of the high level of fruit sugars in ripe pineapple acting as a stabiliser for the foam.

However in the core of pineapple exists an enzyme called bromelain, which is a digestive enzyme similar to trypsin in the way it attacks proteins. If you have ever sliced up a load of fresh pineapple and felt a tickling sensation on your fingers that is bromelain digesting your skin; it's a commonly used ingredient as a meat tenderiser. To avoid the proteins in your pineapple juice from breaking down, one you have juiced the pineapple flesh, bring it quickly to boil to denaturalise the enzymes. Once cooled, the juice will last for two days and provide a gorgeous head every time.

Another option is to use a soy-derived protein - soy lecithin will give you the same result in terms of creating protein strands when emulsified - however a higher sugar content in a drink will make a more stable foam in the finished product as soy proteins create a weaker bond and require more stabiliser.

In terms of methods of emulsification, there are a few methods to properly activate the proteins for a final drink:

- The classic dry shake: shaking the cocktail without ice first to aerate and blend the mix. (A common question is why is it called a dry shake when the shaker contains liquid? The answer of course being that it is shaken without ice first so no dilution is achieved - hence keeping it dry.)

-A whipping article added to the shaker: classically the spring from a hawthorn strainer added to a shaker and dry shaken, although this is messy and somewhat of a ball ache. Other items that can assist are the metal balls from protein shakers, while Alcademic's Camper English suggests cat toys.

-Immersion blender: A stick blender can do wonders in quickly whipping proteins into light, fluffy piles before shaking, and removes the hassle of a double shake.

-The inverse dry shake: friend and occasional nemesis Jay Gray espouses the benefits of the inverse dry shake; that is, shaking with ice first, fine straining the mix, then dry shaking it before serving. I'm not 100% sold on the science of this, as diluting the mix first would in theory result in weaker protein bonds  in the final solution. He swears by it's efficacy however, and I swear against it, and then we both swear at each other.

-The crushed ice time saver: Popularised at Bulletin place, this method does away with the dry shake, with crushed ice pulling double duty as both a diluter and emulsifier, which is then fine strained out of the final drink and resulting in a consistent and silky smooth finish to the drink.

Finally, I thought I'd add a recipe from a few months ago for a vegan-appropriate amaretto sour using soya lecithin extract; it is distressing how many people enjoyed this one

The Lagomorph

nb: Lagomorph being the genus name for rabbits. No, my jokes aren't funny in person, either. 

45ml Amaretto

15ml Amaro Averna

30ml Blanched carrot juice

20ml lemon juice

1 bsp soya lecithin

Dry shake vigorously, wet shake and strain into a chilled sour glass. 

Garnish with dehydrated "Rabbit Ears"

In Defence Of Artificial Aging Pt.3

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We've covered the various factors in aging spirits that affect the final taste of a product as it comes off cask. But know we know how the flavors in an aged spirit are made, can we manipulate these factors to speed up this process without losing the final quality of an aged product?

Before we get started I want to address the obvious taboo im sure that we are about to breach, the one that has been preached to us for many years, that age in spirits automatically equates to a superior product. 

If you look at the history of advertising for spirits,  the aged spirit as a luxury item has onoy really been advertised since the late 1960s. In fact the best source of advertising for spirits, to see the rise of aged spirits and vodka in popularity in the American market (at the time the biggest global spirits consumers), is the most popular mens magazine of the time- Playboy. If you can get your hands on a wealth of vintage magazines it is interesting to track the development of advertising over a generational timeline (honest honey, I omly read them for tbe vintage rum advertisements!).

Aging for extended periods of time was never a viable economic option for small producers, and it still isn't today - it takes an incredible amount of capital to be able to put a large amount of distilled spirit down for 18-odd years, especially when even in the hands of the best cellar masters and blenders there is no guarantee it will taste good.  

Sure, the ability of wood to strip out negative flavor compounds in a spirit was recognized, as it had been by winemakers for generations, but the marketing of age as defining a premium product is only a relatively new development, as we have come to realize that extended barrel interaction means more extraction of these tasty flavors consumers love so much.

A lot of purists will be quick to claim that messing with the aging process is verboten, lest we mess with the delicate craft of the cellar master. However large suppliers have already begun experimentation into how controlling and manipulating conditions can speed up the aging process.

At the end of the day the spirits business is a business at heart, and long aging times do not make for a happy accountant. Any method by which to increase aging without compromising quality can and will be explored.

One of the most traditional examples of manipulating the aging process is found in the Norwegian Aquavitt Linie. As the story goes, casks of the spirit were shipped to either Batavia (Indonesia today) or Australia from Norway in ex-sherry casks, with some merchant or another hoping to sell the spirit there. 

No-one seemed to care for the spirit though, so the casks were shipped back to Norway, where the proprietor found the spirit had taken on a sweet, woody character from the casks, and thus Linie was born. Today the spirit still crosses the equator twice, going into barrel at 60% abv in 500 litre ex-oloroso casks strapped to the deck of a container ship. 

The 19-week passage takes the aquavitt through fluctuating temperature, humidity and pressure zones, while the constant movement of the boat means the spirit is constantly washed against the oak of the barrels, increasing the percentage of spirit to wood surface area contact. This is a great example of manipulating variables to increase aging; 5 and a half months aging in Norway would not yield the results that the constant agitation and changing atmospheric conditions that Linie goes through on it's voyage.

Speaking of ships, Jefferson Bourbon recently released an extremely small batch (200 litres!) expression of Ocean-Aged Bourbon. Interested to see what effect the constant agitation, salt air and atmospheric pressure would have on barrel aging, he aged three 200-litre barrels on the deck of a...shark chasing research vessel?

Insert 'Jaws' reference here

So after four years of following sharks around the pacific, we can see the effect the agitation had on the spirit below - bear in mind the standard Jefferson's to the left and right of the bottle have been aged for eight years, not four.

Wow

So manipulating these factors can have an effect. But both of these methods still provide too many uncontrolled variables. How much agitation is applied? What if one batch goes through a particularly stormy month and the other suffers the doldrums of flat seas? What is the temperature fluctuation, the salt content of the air, how much do these change as the ship travels?

A better way to impart woody flavors to a spirit quickly and with much more control over variables would be to use gas pressure to force a 'flash' infusion. This requires an isi canister, or cream whipper, your white spirit, a gas canister, and wood chips. Wood chips have the added benefit of having a much higher surface area, so it is much easier to extract flavor from the wood. 

While I went into further detail regarding the exact mechanics of how this process works in an earlier post, the basic science is that when released into the chamber, the gas forces its way into whatever porous material it can find as pressure increases. As the pressure is released so is the gas, and flavor compounds are quickly forced out of the material and into the spirit, instantly giving a cold infusion of sorts. 

A plus side to this is you can infuse spirits with many types of wood that would otherwise be too porous for use for barrel aging. I've listed below a few different types of wood and their properties for aging. 


Acacia - Robinia Pseodoacacia

Hard wood, low pore count on the oak; would require extended aging to extract any flavors. High in aromatic aldehydes: Vanillin, syringaldehyde (spicy, smoky, hot and smoldering wood aromas), dihydroxybenzaldehyde (cork must, organic matter). 
No presence of eugenol (That spicy clove & menthol note)

Mulberry - Morus Alba 

Tender, elastic wood. Too soft to construct barrels from, low organic compounds, low eugenol content. High in fatty acids (creates unpleasant esters)

Chestnut - Castanea Sativa

Too porous for barrel aging, but excellent for flash infusing. Contains very similar volatile compounds to Quercus Robur, namely vanillin, syringaldehyde, eugenol, and alpha terpineol (floral, similar to lilac; present in Lapsang Souchong teas). Notably lacks any of the whiskey lactones (cis- or trans-).



Cherry - Prunus Avium

Again too porous for barrel aging, but excellent for flash infusing. Low aromatic compounds, low eugenol, low fatty acids. No real draw to this wood, except for something called trimethoxyphenyl, which I can only find described as 'bland'. 

One downside of flash infusing is that it does not have the effect as extended barrel-aging, that of the evaporation of either water or ethanol, the "angel's share" we discussed last time, does not occur when the effects of the wood are meted instantaneously. By equal parts, you also avoid the potential development of unpleasant esters and acetone odors that can be present in spirit aged for longer periods.

One Last Thing...

A few months ago the story of Miami Club Rum, a rum that aged it's rums by playing Cuban Salsa at the barrels during the aging process, made the rounds to differing reactions of bemusement and derisiveness. At first I gave little thought to this very unique method, as it sounds at best like a marketing gimmick, and at worst like the sort of psuedo-scientific claptrap that drives me to drink.

It wasn't until later (in the pub, of course) that I started to give the idea some more thought, specifically the science behind the idea. You see, sound travels in waves by creating pressure in the medium through which it travels, decreasing in pressure and intensity as it propagates.

However, when a sound wave intersects with another sound wave, there is no affect on the propagation of the wave, but if pressure is measured at the point of wave intersection, there is a change of pressure. If two low points in the wavelength intersect, they end up with a higher pressure reading, and if a high and low point collide they cancel each other out and no change in pressure is recorded.

The first time I came across this particular occurence was when I was introduced to something called "Tibetan Bowl Therapy", a particular theory wherein several copper bowls are placed on various parts of a patient and rung at certain tones to illicit a muscular response. 

I originally approached this method with a healthy dose of skepticism, partly because it was being administered to me by an old man in the attic of a church in eastern Switzerland who didn't seem even slightly Tibetan. It was a...strange time.

Anyway, it did do wonders for relieving muscle strain, and I later contemplated the science beyond the mysticism that these treatments are often presented with. By creating low-frequency vibrations in a circular arrangement, the bowls created an intersecting point of increased pressure within muscle tissue, effectively 'massaging' with sound.

Propagation of Sound Waves Intersecting on Barrel

As you can see in the diagram above, if you were to arrange speakers around a barrel as above and constantly play music at it, the sound waves would intersect at multiple points on and inside the barrel, creating pressure around the staves and inside the barrel content, agitating the liquid contents in a similar method as leaving it on a sea-bound boat, and forcing liquid into the wood faster than it would if left alone. 

Moreover, if you were to play music that had high shift between low-frequency high pressure notes and higher, less decibel heavy notes (like for example, Cuban Salsa music) the effect would be similar to the capillary effect in the wood caused by day-to-night atmosphere transitions experienced by traditionally aged barrels.



So is the method employed by the Miami Rum Company a legitimate attempt at artificial aging based on sound science, or just a marketing gimmick? Well, I'd tend toward the latter myself, but this is all conjecture.   

What we have now however, is the potential for two experiments to test the theories and science we have discussed in this series.

Experiment 1:
Does playing sound at barrel-aged spirits affect their maturation speed?

By setting up a control and a few test cases, we can see if there is any reality behind these claims, and more importantly, which type of music makes liquor mature faster and by extension taste better?

And the big one:


Experiment 2:
By manipulating atmospheric conditions, can we reduce the maturation time of a spirit?

We've talked a lot about the different atmospheric conditions that affect the aging of a spirit in wood. But by taking a barrel and filling it with new make spirit, can we recreate an equivalent quality of an aged spirit in a fraction of the time? 

So here is the challenge we set ourselves:

Can we mature and recreate the quality of a 3-year aged spirit in only one week?

We will keep the blog updated with progress on each of the experiments as they happen, but follow us on twitter @Zero_G_Drunk to keep up to date with this and our other news.

Thanks for reading this series as it's progressed, it's been fun. 

See you next time Space Cowboys.

BG