Posts Tagged ‘alcohol’

Nocino – walnut liqueur (part II)

Friday, May 29th, 2009

nocino-glass

As I mentioned in the post about the exciting color chemistry of nocino I picked some unripe walnuts last year in August when visiting family in Germany. These walnuts were in fact a little to ripe to make nocino from. Preferably the walnuts should be picked end of June when you can still push a knitting pin through the center. Mine were stone hard, but I decided to give it a try anyway, and it shure was worth the bottle of vodka! I checked a couple of recipes and found that many use cinnamon and cloves together with lemon (with peel). I figured I also wanted to try star anise and proceeded with two batches.
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TGRWT #14: Beer sorbet with soy marinated melon

Saturday, January 31st, 2009

beer-sorbet

tgrwt-14As malt was one of the foods to pair for this month’s TGRWT I decided to do something with beer. I first considered making a beer gel since the Alinea book has a nice recipe (with potassium citrate and kappa carrageenan – I included the recipe in the hydrocolloid recipe collection), but since I didn’t have carrageenan at hand I decided to try a sorbet. A quick search gave me 4 recipes (links in the table below) and in order to compare these I decided to calculate sugar/beer and sugar/liquid ratios as these are quite crucial in order to obtain the desired consistency of a sorbet. The results are shown in the table below. (more…)

Wonders of extraction: Ethanol

Sunday, June 8th, 2008


Extraction of cherries with ~45% ethanol in water

Ethanol is a molecule with both a polar and a non-polar end, so it’s properties are somewhat in between those of water and oil (which will be the topic of the next post in this series about extraction). This is easily illustrated by the fact that both water and oil are soluble in pure ethanol (albeit not at the same time – adding water to ethanol reduces the solubility of oil). Many taste molecules are polar whereas most aroma molecules are non-polar, and the good thing is that ethanol can be used to extract both groups of compounds.

I belive the most widespread use of ethanol for extractions in the kitchen is for sweet liqueurs where fruits or berries are extracted with ethanol and the extract is sweetened with sugar. The word liqueur comes from the Latin word liquifacere which means “to dissolve”, and this is essentially what happens – the ethanol and water extract and dissolve flavor and color from the fruit.

Some also make their own spirits by infusing spices and herbs. One example is aquavit which is based on carraway combined with a number of other spices for complexity such as dill, coriander, anis, fennel, liquorice, cardamom and lemon. Commercial aquavits are distilled, but at home it’s suffices to filter of the spices and herbs. As a result home made aquavits are always amber colored (such as the one pictured in a previous post).

For extractions like these, one always uses diluted ethanol, typically 30-60% ethanol in water would be used, and most often somewhere around 40-50%. One reason for this is that higher concentrations of ethanol would extract to many bitter and astringent compounds. Another reason is that in some (most?) countries it is illegal to posess, buy and/or sell ethanol at higher concentrations for consumption (pure ethanol for technical use is denatured if sold in normal stores and requires special permissions if used in laboratories).

Apart from the steping herbs and spices in ethanol to make liqueurs, the only other example of relevance for the kitchen I can think of is for extraction of vanilla beans to make pure vanilla extract. This is quite surprising actually, and although I really don’t know if ethanol is used for extraction in professional kitchens, it is my impression that ethanol extractions are underutilized in the kitchen.

There are several benefits with ethanolic spice and herb extracts:

  • fast – no need to wait for the spices to be extracted since they have been “pre extracted”, you can taste the dish immediately and add more spice extract if necessary
  • no residues – seeds, leaves or bark are filtered off before use
  • convenient – spice extracts are an excellent way of adding clean, concentrated aromas
  • stable – spice extracts keep very well (although the storage may also change the flavor profile somewhat and “mature” the flavor)
  • new flavors – some spices and in particular herbs will change upon extraction and storage and this can open up new possibilities (this needs quite some experimentation though – some herb flavors change to the worse…)

What are your experiences with ethanol extractions in the kitchen?

Edible cocktails with gelatin

Tuesday, October 16th, 2007

edible-cocktails.jpg
Recipes for Bluberry martini jelly shots (top right), B-52 jelly shots (bottom right), Prosecco gelée (middle left) and Gin and Tonic gelée (middle) are given below.

Just wanted to point you to a beautiful picture gallery of edible cocktails accompanying an article by Betty Hallock at LA Times, “Cocktails you can eat”.

The recipes (shortened and converted to metric units by me) are as follows:

Blueberry martini jelly shots
300 mL vodka (blueberry flavored)
60 mL simple syrup
25 g gelatin (6.9%)
35 fresh blueberries

Mix vodka and syrup in small saucepan. Add gelatin and leave for 5-10 min until soft. Gently heat saucepan and stir until gelatin dissolves (approx. 10 min). Strain to remove any undissolved gelatin. Place bluberry in cocktail mold and pour vodka mixture into each mold. Cool until set. Makes about 35 cocktails of 15 mL each. (Adapted from Bar Nineteen 12)

Prosecco gelée
1 length of a vanilla bean
140 g sugar
15 g gelatin sheets, bloomed (3.1%)
340 mL Prosecco (or other white wine)

Scrape seeds from vanilla bean and mix thoroughly with sugar. Mix water and sugar in saucepan and heat over high heat until syrup almost comes to a boil. Remove from heat and bloomed gelatin and stir until it dissolves. Add wine and stir gently. Pour into 20 x 20 cm pan lined with plastic wrap and cool until set. Cut into squares, turn upside down to display settled vanilla beans and serve. (Adapted from Craft pastry chef Catherine Schimenti)

B-52 jelly shots
170 mL Kahlúa
170 mL Baileys
170 mL Grand Marnier
24 g gelatin sheets (4.7%)

Place each liqueur in separate bowls and add 8 g gelatin to each. Cover and leave until gelatin has softened. Pour Kahlúa/gelatin into a saucepan and heat over low heat until gelatin dissolves. Strain to remove any remaining solids. Pour liquid into a 10 x 20 cm pan lined with plastic wrap. Cool for about one hour. Repeat with Baileys, and then with Grand Marnier, pouring the newly prepared liqueur on top of the set liqueur in the mold. Cut into pieces and serve. (Adapted from Bar Nineteen 12)

Gin and tonic gelée
170 mL gin
10 g gelatin (2.2%)
280 mL tonic water
finely grated zest of 4 to 5 limes
1 T citric acid
1 1/2 t baking soda
1 T powdered sugar

Let the gelatin soften in gin for 5-10 min. Heat over low heat and stir until gelatin has dissolved. Pour in tonic water carefully (to avoid it from bubbling over), swirl the contents to obtain a homogeneous mixture and immediatly pour contents into 40 mL molds. Cool. To serve, unmold the gelée and sprinkle each cocktail with lime zest and a little of the premixed citric acid, baking soda and powdered sugar. Serve immediately. (Adapted from Providence pastry chef Adrian Vasquez) For reference, you might want to compare this recipe with Eben Freeman’s Jellied G&T.

You might notice that the amount of gelatin varies over a pretty large range from 2.2-6.9%. This is also well above the typical concentration found in jellies (0.6-1%). A possible reason for the large range would be that alcohol interferes with the setting of gelatin, and a quick plot of gelatin vs. alcohol content suggests that this might be the case.

gelatin-alcohol-plot.png

But as you can see from the B-52 jelly shots, the same concentration of gelatin is used for Baileys (17% alcohol), Kahlúa (26.5% alcohol) and Grand Marnier (40% alcohol), so there should be some room for variation here (I doubt that the resulting variation in texture was actually intended in this recipe). So if we round off, the linear regression yields the following correlation between gelatin and alcohol:

% gelatin to add = (% alcohol in final mix x 0.1) + 2

One thing that surprises me is that none of the recipes call for gellan? This hydrocolloid is said to have superior flavor release properties as it is more prone to break once you chew it. From what I know, it should work fine with alcoholic beverages. Has anyone tried this yet?

New perspectives on whisky and water

Sunday, June 3rd, 2007

whisky.jpg

Among dedicated whisky/whiskey drinkers it is customary to add a little water as this “helps to unlock and release the esters, or flavours, from the fats”. Another site claims that dilution helps “breaking down the ester chains and freeing the volatile aromatics”. Does this make sense from a chemical perspective?

When Erik posted me a question some months ago about why we add water to whisky and the chemistry that is involved, I started to speculate about possible mechanisms and discussed them with Erik. Perhaps the most obvious effect is that the alcohol concentration is lowered. High alcohol concentrations anaesthetises the nose and sears the tongue (as the site metioned above correctly states). This is especially true for cask strength whisky which can exceed 60% ethanol. We considered the possibility of a temperature effect. The obvious effect could be achieved by adding water with a different temperature to either cool or warm the whisky. The less obvious effect could be due to a possible release of heat when adding water to a concentrated ethanol solution. Having thought about the different possibilities I did a search and found a very fascinating article: “Release of distillate flavour compounds in Scotch malt whisky”. It was published in 1999, but was new to me and gave me some totally new perspectives on whisky and water. When reading the article, it seems to me that the motivation for adding water to whisky is in fact to mask some aromas and release others!

Malt whisky contains high concentrations of esters and alcohols with long hydrocarbon chains. When water is added, the solubility of these esters and alcohols decreases, and a supersaturated solution results. In extreme cases, the decreased solubility of fat-soluble, volatile organic compounds can lead to clouding due to precipitation of small droplets as seen with anise/liquorise liqours such as Pastis, Pernod, Arak, Raki, Sambuca, Ouzo… (I think I’ll post about that later some time). This can also occur with whiskys that haven’t been chill-filtered. But even in whisky that has been filtered at low temperature a form of “invisible” clouding will occur. The excess of esters and alcohols in the diluted whisky form aggregates (or micelles) which can incorporate esters, alcohols and aldehydes with shorter hydrocarbon chains. Once these compounds are trapped in the aggregates, surrounded by longer chain esters and alcohols, they smell much less since they have a harder time escaping from the liquid! Fortunately, some of the compounds that are trapped have less desireable aromas described as oily, soapy and grassy.

The presence of wood extracts originating from the aging in oak barrels also influences aroma release. One effect is that wood extracts displace hydrophobic (fat soluble) compounds from the surface layer of the whisky (this effect is significant at room temperature when smelling the whisky, less so at 37 °C in your mouth). Furthermore the presence of wood extracts increases the incorporation of hydrophobic compounds into the agglomerates mentioned above.

diluted-whisky.jpg

So far I’ve only discussed the aggregates formed by long chain esters. But studies have shown that when an aqueous solution contains more than 20% ethanol, the ethanol molecules aggregate to form micelles, just like the long chain esters do. These micelles can also trap flavour compounds. Unlike the micelles formed by the long chain esters however, the ethanol micelles break up when diluting the whisky, thus releaseing the entrapped flavour compounds. It is interesting to note that ethanol is less “soluble” in water at high temperatures (ie. the solution is no longer monodisperse). As a consequence, serving whisky “on the rocks” will actually promote the release of flavour compounds from the ethanol micelles. As Mirko Junge commented below, this is one of the very few cases where cooling actually enhances flavour! But the wood extracts found in whisky matured in oak casks supports the formation of ethanol micelles, so as Mirko Junge points out, matured whisky needs more dilution and/or cooling since there are more ethanol micelles.

diluted-whisky-2.jpg

The over-all effect is a fractionation of volatile compounds upon dilution with water: water insoluble compounds are concentrated in the aggregates (or micelles) of long chain esters, water soluble compounds remain in solution and compounds (probably those which are slightly soluble in water) that were originally trapped in ethanol micelles are liberated.

So after all, the popular notion that addition of water “opens up” the aroma of a whisky is true, but who would have thought that the effect is a combination of “masking” (inclusion of some arome compounds in long chain ester micelles) and “demasking” (opening up of ethanol micelles) and that there even is a temperature effect?


Serving whisky “on the rocks” helps break down ethanol micelles due to the combined effect of cooling and dilution. (Photo by Generation X-Ray at flickr.com)

Feel free to share your experiences with whisky dilution in the comments section below!

(Note: The text has been revised and expanded on June 3rd following the discussion below. Special thanks to Mirko Junge for his valuable comments and for pointing out the importance of the ethanol micelles.)