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.

Maraschino Cherry 101 (literally, there is a one credit course at U. Oregon)

Maraschino Cherry: A Laboratory-Lecture Unit (an un-locked paper from the Wiley online library.

Apparently since 1994 Oregon State University has offered a 1-credit class about the making of maraschino cherries. The cherry is used to illustrate food chemistry, the fragmentation of processing unit operations, microbiology, food safety, food law, sensory analysis, and product development. The course seems like it would benefit culinary professionals working on next generation, modernist recipes.

Consider as you read the little bits I’ve extracted, just how different are Luxardo cherries? They are also gloppy pectin filled horrors but maybe just with better aroma added back after the leaching?

The course covers a lot of nitty gritty chemistry stuff: sulphur, calcium chloride, acidulants like citric acid & hydrochloric acid, sodium chloride, all for the cherry “brine” formulations.

How do they bleach the cherries?

*Cherries get a sulfite based primary bleaching brine in which they sit for three weeks

*Cherries follow up with a chlorite based secondary bleaching brine but only after the primary brine is carefully leached out with boiled water to reduce the sulphur content. “bleaching of brown discolorants will take from 5 to 10 days”

*The secondary brine gets leached out and they can return to the primary brine until they are ready for processing

cherry flow chart

“Calcium plays a very important role in the brine formulation by giving the cherry a firmer texture. If the pH is greater than 4, calcium will precipitate from solution as CaSO3 and not be available. The divalent cation forms salt linkages between the galacturonic units of 2 adjacent pectin molecules.” …hardcore chemistry blah blah blah… “This cross-linking of cell-wall polysaccharides results in a firmer fruit texture that is not only more acceptable from a sensory standpoint but also facilitates mechanical pitting.” [#Pectin<3Calcium #Luxardo!]

“The brined cherries are yellow in color since the yellow carotenoids are not affected by bisulfite. It should be emphasized that the primary function of bisulfite is to prevent microbial growth, and that bleaching of the cherry is a secondary role.”

“With the advent of mechanical harvesting of cherries in the 1960’s, the number of cherries with defects from bruising increased substantially. Cellular damage permits the enzyme polyphenoloxidase to come in contact with fruit phenolics-forming quinones, which subsequently polymerize to form brown pigments. A secondary bleach process utilizing sodium chloride was developed by Oregon State Univ. researchers that bleaches the brown discoloration along with the carotenoids to produce a snowy white cherry.”

The brining process here is probably what I need to complete my project of embedding cocktails in fruit structures to illustrate how texture and haptic heft change thresholds of perception. I had previously been trying to wash the color out of golden raspberries by soaking them in vodka/sugar brines that I changed periodically. Brining plus reflux de-aeration will make this possible.

The cherries get sorted and supposedly only by size. When I make my alcoholic version, I sort cherries by density, but I guess when you can firm the texture with a calcium brine brix can more easily be augmented without swelling or shrinking so they can sort and just be concerned with size. They explain more of the leaching process and how it is an environmental problem because of BOD (biological oxygen demand).

“The optimum Brix of cherries for brining is from 12 to 15 degrees compared to 18 to 22 for fresh market or canning…”.

“Maraschino cherries commonly have a Brix of 40. The drained, brined cherries cannot be immediately introduced to the 40 Brix syrup or shriveling will occur as water rapidly diffuses from the fruit to the syrup. Therefore, the drained cherries are introduced to dilute sugar syrup, for example, 15 Brix and sufficient time, for example 12 h, is allowed for equilibrium. The sugar content is increased in 3 to 4 Brix increments to gradually introduce sugar without tissue damage.” [#bigtradesecret]

“Since SO2 levels have been markedly reduced, preservatives such as potassium sorbate and sodium benzoate are included in the syrup to prevent microbial growth.” [#sadbuttrue]

[…]”The pH during processing and final bottling is targeted for approximately 3.6 to 3.8. Citric acid has several functions

*It provides flavor, the Brix:acid ratio giving a good numerical index for the sweetness to sourness taste quality […]

*The effectiveness of sodium benzoate and potassium sorbate as antimicrobial agents is dependent on pH. Un-dissociated benzoic acid is the form with antimicrobial activity, optimium activity occurring in the pH range of 2.5 to 4. Sodium benzoate is most active against yeast and bacteria and least effective against molds. Sorbic acid and its sodium and potassium salts are particularly effective in preventing mold growth, the activity increasing with decreasing pH. [why you need both!]

*[…#botulism blah blah boring]

They explain the pearson square for working with sugar.

The section on coloring is sort of painful.

“Flavoring is added after the sugar concentration of the cherries reach 40 Brix. Most of the flavor volatiles originally present in the cherries are lost during the brining and leaching operation, leaving a product characterized principally by the sharp taste of residual SO2. Benzaldehyde is a naturally occurring compound that contributes significantly to the flavor of both sweet and sour cherries. Since almonds are an even richer source of benzaldehyde, almond extract was a logical choice for flavoring maraschino cherries. […] Artificial flavorings for maraschino cherries will have benzaldehyde as a principal ingredient. If the processor prefers to use natural flavorings, almond and/or cherry extracts will be commonly used.”

The finish by explaining some labeling laws.

One cool reference ends up in the bibliography that I’d love to track down:

Filz WF, Henney. 1951. Home preparation of maraschino cherries. Afr Exp Sta Bull Nr 497. Corvallis, Oreg: Oregon State College. p 1-11.

Searching for that book turns up a really interesting masters thesis on maraschino cherries.

Cerises au Soleil

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[This post is horribly out of date and has some flawed concepts that I have since learned quite a bit about. A new recipe is part of my distillers workbook that references some great literature and unlocks more of the mysteries of the preserved cherry. Anyhow this is what I was dong back in 2008]

In the last couple weeks many forces have been preventing me from making it to Hay Market but today I finally got there. After checking out all the vendors, I bought four pounds of cherries for two dollars a pound (two pounds of Rainier, two pounds of Bing).

Cherries are not a big part of my diet and I usually only ingest their flavors through wine. The Rainier cherries are quite sweet relative to the Bing and my understanding is that the peak of their season is in July. In wine I’d say you might experience the Rainier flavor in the fruit of a lightly extracted rosé. The Bing variety has the most stunning sour quality and are really refreshing. They are really juicy in flavor and I think I should eat more of them. Bing cherry as a wine descriptor is thrown around quite a lot, but I can’t think of any wine that truly captures their flavor which is quite concentrated. A very young Dolcetto would be the best bet. The Piave liqueur Elisir Gambrinus synthesizes a Bing or probably better yet Marasca cherry like flavor by reducing the wine of the weed grape Ribasso. Only after concentrating the flavors (it makes a bland wine on average), does it come close to the intensity of a raw cherry.

So I bought all these cherries because one of my favorite discoveries of last year was the Provencial specialty called Cerises au Soleil or cherries of the sun. In this canning tradition, the French jar cherries with sugar and eau de vie then age them on roof tops for the duration of the summer. I got a couple jars of the imported version at formaggio kitchen and used them for a special Brown-Forman cocktail event I did for a couple hundred people last year. The product was great but the only thing I didn’t like was that the pits of the cherries were intact making them slightly difficult to eat.

For my recipe I cleaned and pitted all four pounds of cherries and put them together in a three liter mason jar. Instead of eau de vie, I added 750 mL of cachaca and 750 mL of Stock brand maraschino liqueur because both ingredients were on hand. I then added a small fraction of the pits that I took out to add a subtle nutty character. If I smell too much of that nut character I feel like someone is trying to poison me with cyanide. (if I ever put an almond liqueur in a drink, I need a float of dark rum to cover up that unnerving smell). So the only sugar I’ve introduced to the cherries has come from the maraschino liqueur which is quite sweet. The sugar content is enough to make the preserving liquid dense enough to float the cherries which is not where I want to be. Herve This advises in his Molecular Gastronomy that the proper sugar content for canning fruit in syrup is one at which the fruit doesn’t all fall to the the bottom (not enough sugar) or all float (too much). This is complicated by the differing ripeness of the fruits which is exacerbated in my batch by the differing varieties (I’m not stressing, at good average is what I seek). At the moment all of my fruit is floating and I should take out some of my alcoholic syrup and add either water or more Cachaca. Optimizing the syrup will keep the fruit from bursting if the sugar content is too low or shriveling if it is too high. Every home made maraschino cherry I’ve had has been shriveled, while the Cerises au Soleil from Provance were perfectly shaped. (I’m also not afraid of wasting any booze to get the correct maraschino liqueur to Cachaca ratio because anything I take out is going to flavor some sangria)

The next interesting part of the recipe to consider is the sun. Submitting the jarred cherries to the elements especially sunlight induces oxidation and basically speeds up the aging process. Maynard Amerine describes aspects of the idea in his Technology of Wine Making but doesn’t exactly recommend any of it. The technique may not create any attractive flavors in a wine or brandy but may add further sophistication to the over the top flavors of unfermented fruit. I keep putting my batch out in the sun when I work lunch while I’ve heard of other people decorating their gardens with their canning jars. Time will tell exactly how much I like my domestic results.

Some ideas for down the road would be to augment the acidity to my liking. I really enjoy aspects of the Rainier cherries but feel that they are kind of sweet. Diffusing a little extra acidity through a sprinkling of malic or tartaric acid would really create a preserved yet refreshing palate cleanser. Also enhancing the preservation with avante garde base spirits would be cool. A really minerally Cape Verdean rum or over the top Peruvian pisco would add awesome sophistication.

**** update****

So mixing the two types of cherries turned out to not be a great idea because their colors became kind of homogeneous and they definitely had drastically different densities therefore requiring different amounts of sugar (half sunk and half floated). I do think they taste good but for some reason the cherries taste far more alcoholic than the liquid they are in and I have no idea why. Another problem is that the cherries at the very top of the jar have browned due to oxidation. None of the imported Cerises au Soleil browned even though there was no preservative listed and the jars were not even filled to the top. How did they do it?

I found a clue in the electronic addition of Artisan Distilling by Kris Arvid Berglund. Berglund provides a small and very useful guide for small distilleries that is definitely worth checking out. An interesting part of the guide describes the tradition of the pear in the bottle of eau de vie and what it really takes to make it stick. Apparently an 80 spirit isn’t enough to really preserve a fruit and prevent browning. For starters Burglund recommends a 45% alcohol spirit. Then very surprisingly to me, Burglund recommends filling the bottles with a 1% sulfuric acid solution and letting it stand for one hour. The bottles are then thoroughly rinsed with softened water. One gram of ascorbic acid is dissolved in every liter of fortifying brandy. After filling the bottles Burgland recommends to vacuum out the oxygen as well with something like a water jet pump or maybe a vin vac (I have no idea how you would do it to a canning jar). Another surprise to the story is that often the fruit has to wait in the jar quite a while before the eau de vie is even ready for it. to preserve it in the mean time a solution of 10 g citric acid, 1 g ascorbic acid, and 100 mg SO2 (= 2ml SO2 solution 5%) per liter which can supposedly preserve the fruit for up to six months while the eau de vie is being produced.

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