Distiller’s Workbook exercise 14 of 15

[This recipe is the accumulation of many years of playing around and connecting the dots. It will likely make your head spin at first but give it a try. Please, if you have any criticism, leave a comment.]

Fernet Aromatized Maraschino Cherries

Distillers can do more than just make distillates and this exercise explores some of the possibilities. Here we are going to make a modern and very much in vogue version of the alcohol preserved maraschino cherry as well as propose some ways to deepen involvement and eventually refine the process. The exercise will have no explicit recipe because the inputs are so dynamic but rather just guidelines and formulas that never extend beyond simple algebra and can be followed to give a rewarding product.

Lots of research has been done on manipulating cherries, and believe it or not, there is even a one credit course at Oregon State University on the production of non-alcoholic maraschino cherries. The OSU course explores the tricky and certainly novel, but slightly gross process of brining the cherries which will be contrasted with the alternate process used in the exercise.

The often lamented cherries described in the OSU course are brined with preservative sulfites and have their texture enhanced by calcium chloride but that is not the only way to skin the cat. Another exemplary cherry is the Cerise au Soleil of Provence which is relatively minimal in intervention and uses alcohol as the primary preservative. Translated as cherry of the sun, they are aged in jars for the duration of the summer on a clay roof top in the countryside. Alcohol preserved cherries require a fair degree of treatment but nowhere near as much as non-alcoholic versions.

Non-alcoholic maraschino cherries get a bleaching brine primarily to prevent microbial growth but also to remove unsightly browning due to mechanical harvesting. The first bleaching brine features sodium metabisulfite, citric acid & calcium chloride and lasts three weeks while the second bleaching brine features sodium chlorite & glacial acetic acid (crystalized form) and lasts five to ten days. The cherries used in the Cerise au Soleil are thus likely hand picked to avoid bruising which would be readily apparent and preserved in alcohol as a mechanism of respecting their natural color & flavor as best possible which would otherwise be lost. For non-alcoholic cherries, despite aggressive brining, ultimately the sulphite level declines to a point where potassium sorbate and sodium benzoate have to be included in the sugar syrup to maintain stability.

Bleaching non-alcoholic maraschino cherries strips them of most all aroma which eventually has to be replaced and is typically done with benzaldehyde derived from the cherry pits which has the aroma of almonds. Dilution of aroma happens to alcohol preserved cherries when they come to equilibrium with the preserving solution they rest in but is overcome by using a spirit of the same aroma so it essentially diffuses in two directions. This means alcohol preserved cherries are best preserved in Kirschwasser which is a cherry eau-de-vie, but other aromas can also be added which will be explored in the exercise.

The calcium chloride of the first brine, in a certain pH range (which explains the citric acid), reacts with the pectin in the cherries, greatly firming the texture and facilitating mechanical pitting. Alcohol preserved cherries are not firmed with calcium chloride and typically have their pits intact to reduce opportunities for browning. No literature states that alcohol preserved cherries cannot be firmed with calcium chloride and it may be a worth while avenue for exploration. Sulfites reduce enzymatic browning and the mechanism is explained well by the OSU course literature. It may not be possible to pit cherries that have not been brined with sulfites without inducing browning. The browning that does form as a result of mechanical harvesting is not actually bleached by the sulfite brine but is rather bleached by the sodium chlorite brine. To avoid using the brining method, the cherries needs to be as carefully handled as possible.

Sugaring the cherries requires a lot of care and consideration. The cherries need to be sorted by density so they can be uniformly sugared. Not all fruit achieves the same ripeness which means that the fruit from a bushel of cherries will have a wide range of sugar contents. If the cherries were mixed randomly, some would sink in the alcoholic preserving solution while others would float. The cherries that floated above the surface would be subject to more oxidation which is what we are trying to avoid. Cherries can be sorted by first estimating the range of their sugar contents then creating a series of testing bins (sugar-water solutions) to see which cherries float and which sink. The bins can vary by 20 g/L increments. Cherries with higher sugar contents will sink while cherries with lower sugar contents will float. To see where they find equilibrium, the cherries will have to be shuffled between the bins. When there is extreme variance between the sugar content of the cherries and the preserving solution, the cherries with less sugar will lose water and shrivel while the cherries with more sugar will take on water and swell, in both cases causing tissue damage.

To get a rough estimate of a cherry’s sugar content, it is helpful to use a wine maker’s brix refractometer which is a small prism that a single drop of cherry juice can be placed upon. The refractometer has a sight glass with a scale that can measure the sugar content via the refractive index of the juice. A refractometer can measure (estimate) sugar content only in non-alcoholic solutions. The beauty of the refractometer (as opposed to the hydrometer) is that it only takes a single drop to get a reading, but the readings will need to be converted from brix to g/L to make the numbers more intuitive to use. Wine makers use refractometers out in the vineyard to estimate the ripeness of single clusters of grapes as the season progresses while bartenders use them to calibrate their various syrups.

The OSU course teaches a valuable lesson about sugar content which is if it starts at the same level of the cherry it can be walked upwards in slow increments to a desired point without tissue damage. Non-alcoholic cherries typically have a sugar content of 470 g/L which of often more than 3 times the starting sugar content. The sugar content can be increased by 30 g/L every 12 hours until the desired level is achieved which for the exercise may just be high enough that 90% of all the cherries can be brought up to a uniform level.

For alcohol preserved cherries, the sugar content is integral to determining the alcohol content because sugar displaces alcohol lowering the proof. Alcohol fortified products are often brought up to the minimum of microbiological stability by alcohol alone which is typically 18%, but that is not the only approach. An idea in dessert wine production exists which lowers the minimum necessary for alcohol as a preservative by measuring and harnessing the preservative power of the sugar content and sometimes other variables like pressure in the case of sparkling sweet wines. Great research from Maynard Amerine at UC Davis explores this stabilization concept and the lessons learned can be applied to far more than just this exercise. Preservative power is counted in Delle units, named after the Russian inventor, Professor Delle, in the early 20th century and stability is often thought to happen at 80 units. To calculate Delle units the formula A + 4.5C = DU is used where A equals the sugar content in brix and C equals the alcohol content. If a sugar content of 18 brix is achieved, an alcohol content as low as 14% can be used to achieve 80 Delle units. Eighty units is not a hard and fast rule but rather just a point to begin trials and exploration.

An alcohol content at the minimum of stability is critical due to a strange sensory phenomenon where the haptic heft of the solid fruit changes the threshold of perception of alcohol making it seem much more alcoholic than it actually is. This same effect can be seen when eating the pineapple chunks from a Stoli-Doli jar. Many people wrongly believe the fruit holds more alcohol than the liquid, but the illusion is just one of the many phenomena of perception. The same phenomenon will also enhance contrast detection of the fernet aroma we are going to add, and even though fernet will only represent 10% of the preserving solution, eating a cherry may feel as though one is taking an entire shot of fernet.

Many people have the notion that alcohol is a complete preservative, but while it does prevent bacterial growth and certain levels can even kill bacteria, it is powerless against oxidation and even enzymatic browning. If you have ever seen a pear trapped in a bottle of pear brandy, besides the alcohol, ascorbic acid (and possibly sulfites) is also keeping the pear company, otherwise it would brown detrimentally. To preserve a pear, the advice is often given of using 1 g/L of ascorbic acid in the preserving solution (as well as rinsing the fruit and bottle with a sulphuric acid solution to kill bacteria on the surface of the fruit), and with cherries we recommend following the same advice as well as vacuum sealing the canning jars to remove trapped oxygen. Ultra violet light from spending time on clay roofs in the sun may also kill bacteria in the case of the Cerise au Soleil.

Considerations need to be made for the alcohol content of the cherries. When the preserving solution rests with the cherries, the alcohol content will come into equilibrium and be reduced, therefore the displacement of the cherries needs to be known. The displacement of the cherries can be found by taking multiple small samples from each bin that differ by density and placing them in a graduated cylinder of water. The weight of the sample can divided by the observed volumetric displacement to find a ratio which can be extrapolated to find volumetric displacement with only the weight of the entire lot.

Awareness of the Delle stabilization concept can either allow a minimal alcohol content for those that deepen their involvement and experiment systematically or it can just provide a very comfortable margin of error.

Every division of the sorted cherries is going to require its own custom preserving solution and the lowest sugar content cherries need a slightly higher alcohol content if the sugar content is going to be walked upwards. Keep in mind, every 30 g/L increase in sugar content has dissolved volume of 18.9 mL which can dilute the alcohol content by nearly half a percentage point and it may take almost two rounds of increasing the sugar to reach that of your ripest cherries. If you are not making your own cherry eau-de-vie, Hiram Walker’s Kirschwasser is the most practical alcohol base. As a starting point, it may also be useful to put each batch in wide mouth canning jars that assume the cherries will displace the same volume as the preserving solution (one volumetric liter of cherries is preserved in one volumetric liter of preserving solution).

Hiram Walker Kirschwasser is only bottled at 45% alcohol which means that once it is diluted by sugar then brought to equilibrium with the cherries in a 1:1 ratio, the equilibrium alcohol content may be lower than is needed. This problem can be solved by either changing the preserving solution ratio to use more Kirschwasser per volume of cherries or by re-distilling the Kirschwasser to concentrate its alcohol content. Simple tests with water will tell if your cherries can be covered by a desired volume of preserving solution or if adjustments needs to be made.

Introducing additional aromas like the saffron-menthe of fernet can push a preserved cherry into something that is over the top and very special. Fernet cannot be re-distilled with the Kirschwasser because it contains a valuable non-volatile fraction which contributes gustatory-bitterness therefore it has to averaged in. Fernet also has a sugar content of approximately 30 g/L.

If need be, re-distill Kirschwasser on low reflux until the thermometer on the still reads 97°C (the high temperature did not seem to produce a cloudy distillate because it had already been cut previously during the production of the inputs).

Add Fernet to the Kirschwasser so that Fernet’s alcohol content represents only 10% of the blend. At 10% of the preserving solution, Fernet’s  30 g/L sugar content will be diluted to 3 g/L before further dilution. It may be safe to consider this sugar content negligible.

The resultant mixture of Kirschwasser and Fernet will have to be cut to match each specific batch it is going to fortify. First cherries displacing one liter needs to be found. At this experimental scale, a two liter graduated pitcher can be filled to one liter with water and cherries can slowly be added until the water level rises to two liters. This liter of cherries will require one liter of preserving solution. The preserving solution will be constructed to match the sugar content of the sorting bin the cherries were taken from. The displacement of the sugar will need to be found to find the corresponding alcohol content. The dissolved volume of a weight of sucrose can be revealed by dividing the weight by the density of sucrose, 1.587.

To find the corresponding alcohol content we can use the equation: (1000 mL – sugar vol. mL (X%))  = 1000 mL (desired final alc.%).

The X variable represents the alcohol content necessary before dilution by sugar to hit the target alcohol content for a single liter. The volume of alcohol necessary per liter is simply 1000 mL – the dissolved volume of sugar. Working this out per liter means it can easily be scaled for any custom batch size.

Now that the preserving solution has been cut and sugared, ascorbic acid will need to be added and completely dissolved. One gram should be added for every liter of preserving solution. The density of ascorbic acid is 1.65 g/mL thus one gram will displace 0.61 mL and probably can be considered negligible.

After the cherries are added to the preserving solution they should be de-aerated to remove all the oxygen clinging to the cherry skin if possible. Pressure de-aeration in a Cornelius keg is a viable option for large batches and vacuum de-aeration with a canning jar lid attachment is effective for very small batches.

If need be, the sugar content of the cherries should be walked upwards to hit a target and the influence of this addition on the alcohol content should always be a accounted for with simple averaging. If the alcohol and/or sugar content becomes lost, a sample of the preserving solution at equilibrium with the cherries can be re-distilled to reveal the misplaced alcohol and sugar figures.

If the cherries are left unpitted time will eventually cause the alcohol to pull the aroma of the pits into the meat of the cherry. If fernet was added to the preserving solution at the recommended scaling, the same phenomenon of perception that decreases the threshold of perception of alcohol, thereby amplifying it, will also amplify the aroma of the fernet making the indulger believe far more fernet was included than the actual.

DIY Barrel Proof Overholt

After dissecting so many spirits I got the idea that I could create a barrel proof rendering of a whiskey by using vacuum distillation paired with a second distillation. The non-volatile part would be separated from the volatile part then the volatile part concentrated in a typical copper reflux still and the two segments rejoined. The change would be a reduction of water and therefore an increase in proof and a concentration of aroma (there are some finer points where fidelity is lost).

In the process, I discovered that my simple glass laboratory vacuum still sucks and is not good at collecting the solvent (I think I know how to tweak it). Time is money and Overholt is cheap so I ended up merging two bottles into one. One bottle was vacuum reduced (using a simple aspirator-to-vacuum flask rig) as far as my patience would take it (from 750 mL to 180 mL, but next time I’ll go all the way). The second was was simply re-distilled at high reflux to 80% alc. The volatile part is not sensitive to heat, so using a conventional normal-temp-atmospheric-still does little to impact the aroma (this is true enough, but not really).

The sensory properties of each half are really interesting. A lot of what a barrel contributes to a spirit is not volatile so re-distilling an aged whiskey reveals something very close to the white dog that went into the barrel. The non-volatile parts were concentrated at about 60C and it was amazing to see how much aroma was there. The non-volatile aromas really seem to define Overholt. The vacuum reduced segment became really turbid and I was afraid I spoiled the color permanently, but after marrying the color went right back to the same beautiful barrel hue.

Unfortunately, patience got the best of me and because I only reduced the non-volatile half to 180 mL, I only ended up with a 55% alcohol finished product, but it still made a lovely Manhattan.

I was really impressed with the success of this technique and am going to pursue it further. Next up is Fernet 151!

Fluid Gels Are Our Future; Fernet Bombardino

My heart bleeds for those with lactose intolerance. It is a terrible affliction, but the pain can be lessened and the problem can be solved by realizing the awesome power of the egg  yolk. Some cultures, often those stricken by poverty, thicken their coffee with yolks. I started doing it years ago by making simple bombardinos then an old Italian woman I came across (Dante’s aunt), told me her mother used to serve her the same, but with fernet when she was a little girl in the old country.

Some fear bombardinos or advocaats because they believe the eggs are raw, but harnessing the idea of a fluid gel they are likely pasteurized, though it does remove a little bit of the myth and the adventure (fluid gels are not so easy to explain, but Modernist Cuisine does a really good job).

Here is my take on the fernet bombardino:

250 mL of fernet branca

40 g non aromatic white sugar (this brings up fernet’s sugar to about 165 g/L)

slightly more sugar can be added to bring the dissolved volume up to an even 300 mL if you like even math which I ended up doing.

200 mL of egg yolks (to yield 187.5 mL because some with cling to the bag) cooked sous-vide at 65°C for 35 minutes to pasteurize.

Fernet has an alcohol content of 39% so when we add sugar with a dissolved volume of 50 mL to 250 mL of fernet we end up with 300 mL with an alcohol content of 32.5%.

To be conservatively stable, we should try to have an ending alcohol content of 20%. 300 mL of 32.5% alcohol diluted with 187 mL of egg yolks yields an alcohol content of 20%.

The sugar also gets diluted to approx. 101g/L which puts it in port wine territory.

The egg yolks at this point are a firm gel, but if we shear them with the colloid mill we can create a very fluid fluid gel that very much resembles cream.

I’m not sure if I will need to add any ascorbic acid as an anti-oxidant, but I did de-gas the liquid with the chamber vacuum sealer.

This is very thick stuff and really clings to the glass but is so delicious! Thank you aunt Anna for the inspiration.

If anything, this recipe has too much yolk, but I think the ending sugar content is perfect. As it is the liqueur is best used in place of an egg in flip style cocktails or as a coffee creamer. To make it as a stand alone liqueur, I would reduce the yolk quotient and re-adjust the sugar content to keep close to 100 g/L.

Bombardino!

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A classic Italian high proof eggyolk amaro

For 500 mL of Zwack Unicum (I want to use Fernet but I’m using the Unicum because I have a bottle, I fear it, and I need to figure out how to use it. It has comparable sugar and alcohol content to Fernet)

Guides suggest a minimum of 14% alcohol which definitely won’t be a problem using Zwack Unicum or Fernet Branca. Guides also call for 140 g/L of egg yolks and 150 g/L of sugar. with a little bit of hydrometer work and some extrapolation we find that Zwack already rings in at 7 brix or so which may only be about 70 g/L (very impercise).

To make 500 mL:
70 g egg yolks (really five yolks @ 77.2 g)
50 g sugar
450 mL or so of amaro.
.5 g of vitamin c powder as an antioxidant

Dissolve the sugar first into the alcohol (with patience) then slowly integrate the alcohol into the egg yolks.

These are the recommended proportions of an old agricultural science manual. Upon tasting it, I like the new mouth feel and see a contribution from the yolks but I really feel I need more. (if not 7 more yolks!) At its present state I don’t see how the liqueur would hold its own to coffee. Seven more yolks will even probably increase the volume by less than 100 mL.

Another 103.7 g of egg yolks.

!! totally worth using the 175 g or so of yolks.

Because I’m making this really quickly, there is some undissolved sugar (due to a lack of patience) and maybe some burnt yolk from the initial high alcohol. Like in a zabaglione, I can get rid of most of this by passing it all through a fine strainer.

There is surprisingly quite a lot for the strainer to remove but the final product is pretty cool. Strong but tamed by the texture of the yolks. A ferocious amaro becomes much more approachable. Now lets see how long it will keep.

I have no coffee but it adds a delicious complexity to earl grey tea.

*****update*****

I managed to drink this with some coffee and it was a delicious rich alternate to cream with extra flavor contrast. I have not worked intimately with Advocaat and have no understanding of how stable it is, but I do notice little flecks of egg yolk separating and I fear it may be from alcohol levels being higher than is stable. The particles can be easily strained off but its not that aesthetically pleasing. Next time I may dilute the intensity of the alcohol with some water. Fernet is full flavored enough that water won’t harm it too much.

****update****

I was trying to make this drink for a small newspaper article on winter egg drinks. I didn’t use the fortified yolk liqueur but merely a quick zabaglione with four yolks, 2 table spoons of sugar, 2 oz. of Fernet, 2 oz. of white wine. the results were really great in hot coffee. Awesome flavor contrast and a certain richness. It even works well in iced coffee.

****update****

So many people search for a Bombardino recipe according to my blog statistics. Of course nearly no one comments on anything. What exactly are you looking for? and how do you know of the drink? Strangely, the drink is rather common on European restaurant menus relative to its obscurity here in America. Any insights on this tradition?

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French Top Punch

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I just recently presented at a charity culinary event for Rett syndrome with chef. Liquor was not exactly part of the presentation but we decided it would be fun to put something together for the chefs and line cooks working the event as well as our attending friends among the many donors to the charity. In the past we have mixed these drinks a la minute or created small batches but I’ve slowly learned the wisdom of the flowing bowl. I actually just did a cocktail party for 40 or so people that really reinforced the wisdom. People only wanted to get drunk. Barely anyone noticed the drinks. And I spent too much time working because I didn’t batch anything. Now for parties I’m only using the flowing bowl format.

This event’s punch required fernet because it was mostly for chefs and line cooks a.k.a. the people who work the french top who are also addicted to the amaro. To make it less masochistic, I added some fruit flavor contrast via chambord (specifically over any other fruit based liqueurs) then something tart to balance (lemon juice) then something bubbly and slightly acidic (cava) to make it more punch like and elegant.

375 ml fernet branca
375 ml chambord
375 ml lemon juice
750-1500ml cava (segura viudas)

Combine all in a punch bowl with large chunks of ice. Change the ratio of cava for your desired alcohol and flavor intensity.

This was loved or feared like the best things in life. I personally felt like I could spend a solid evening drinking nothing but this punch. Those that didn’t like it are already known to be vodka-soda wusses. Some astute drinkers thought the punch brought into focus the aromatized elements of the chambord. If I changed this recipe in any way it would be to add a couple hundred milli liters of Batavia Arrak or Cape Verdean rum.

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