Distiller’s Workbook exercise 11 of 15

Pisco Faux Mosto Verde #Fail

This exercise is ultimately a failure due to the poor sourcing of the Muscat grapes, but is enjoyable enough to drink and ends up illustrating an important phenomenon related to grape selection for distillation. The opportunity to experience faults and minor failures is invaluable to the new distiller so performing this exercise is well worth while. Fermentation and the selection of source materials are beyond the scope of this text but this exercise gives a glimpse of some very important considerations. The foundation of the exercise is the Peruvian distilling technique called mosto verde or green must.

In mosto verde Piscos, fermentation is stopped before completion forgoing potential alcohol so when distilled an exaggerated ratio of aroma to alcohol is created. This works because sugar is not volatile and the sugars do not caramelize at the temperature range of beverage distillation. Mosto verde Piscos are Peru’s most expensive bottlings because of their decadent inefficiency. They are highly regarded in Peru but seldom imported to the U.S. For the exercise, a commercial bottling of Pisco will be re-distilled with unfermented grapes in the form of a concentrate, often called a mistelle, to try and add extra aroma. Mistelles, which can be purchased in many varietal types, are used by wine makers to boost alcohol and sometimes used by liqueur producers to sweeten their products. Unfortunately, the exercise will reveal that not all grapes are created equal and though this technique may be possible in theory, it was not possible with common off the shelf sourcing for reasons that will be explained.

Roseworthy Agricultural College did many studies in the mid 20th century to try and reverse engineer Cognac and the works reveal a lot about the unique aspects of the brandy making process. The wines used for Cognac production are harvested with a very low potential alcohol unlike the grapes harvested for the mistelle used in the exercise. Ripeness has more facets than only sugar content and the quality of aroma precursors is very important to consider as well. As grapes hang on the vine longer and produce more sugar, their stable long lived aroma related compounds change into frailer forms which aren’t as resilient. It also isn’t possible to produce grapes of aroma-centric ripeness everywhere, some regions are considered precocious where aroma related compounds develop early relative to sugar content and acidity and everything comes together just right to make a wine well suited for distilling.

Wines constructed for distilling are often regarded as thin and acidic. These wines, in their wine state, have more aroma precursors than they do actual aroma relative to common table wines. These wines are also very high acid and during distillation, with the help of the non-volatile acid as a catalyst, aroma precursors turn into actual aromas. The mistelle has aroma but the aroma isn’t stable and quickly changes like a wine that becomes too old. The ultimate product of the exercise will eventually develop aromas in common with over aged wines.

Pisco is derived from Muscat and its cousin varietals which are often believed to be simple and regarded with disdain relative to other brandies like Cognac but there is more variation than most people think. Besides the many synonymous names and close genetic cousins, there is also a wide distribution of potential aromas. Under many circumstances, the aroma of Muscat grapes will be dominated by the olfactory-sweet while under other circumstances the aroma will be dominated by the olfactory-umami which can leave many Piscos feeling not too dissimilar to fresh sugar cane juice rhums or even Tequila. Often times the olfactory-sweet aroma of Muscat grapes can seem plebian and ordinary so blending different expressions can be useful to either create extraordinary tonality or stimulate aromatic tension between the olfactory-sweet and the olfactory-umami.

Analyzing the mosto verde technique can raise the question: is anyone else using it? The fresh sugar cane rums of Cape Verde have an astounding aromatic intensity not found in similarly produced Martinique rhums or Brazilian Cachacas. Do the Cape Verdean distillers forgo the last percentage point of alcohol for an exaggerated amount of aroma or is it just the spectacular terroir of their cane?


500 mL Peruvian pisco (we used Macchu Pisco)

100 mL Muscat grape mistelle 68 brix grape concentrate (we used Alexander’s of California)

7 g tartaric, malic, or citric acid (optional catalyst)

Mix and re-distill together slowly on low reflux until the thermometer on the still reads 200°F (93.33°C). Going past 200°F may result in a cloudy distillate or unpleasant cooked aromas.

Using your hydrometer re-cut the distillate to your desired proof with distilled water ( recommended 80-90).


Faux Mosto Verde Sour

1.5 oz. mistelle aromatized Pisco

.75 oz. lemon juice

.75 oz. simple syrup (1:1)

egg white

dry shake and then shake again with ice

decorate with Angostura bitters



1.5 oz. mistelle aromatized Pisco

.75 oz. Pimm’s no. 1 cup

.75 oz. lemon juice

3 g. non aromatic white sugar

combine ingredients then stir in the sugar to dissolve

shake with ice and double strain


Me and My Grandfather

.75 oz. mistelle aromatized Pisco

.75 oz. Cognac

.75 oz. lemon juice

.75 oz. simple syrup (1:1)

2 thoughts on “Distiller’s Workbook exercise 11 of 15

  1. A phenomenon that could be happening to the mistelle which makes it taste frail and card boardy is lipid oxidation. Lipids are basically all the fatty acids that can go on to become esters. Lipid oxidation is described as challenge for Bourbon producers in T. Lioutas article “The renaissance of American Bourbons: developments and technical challenges of the production of premium Bourbon distillates by batch distillation”. The article is Chapter 33 of the text: Distilled Spirits: Tradition and Innovation.

    According to the article, Bourbon beer has a staggeringly high lipid content relative to Scotch whisky mash. I had never heard of fatty acids called lipids in the context of distillation.

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