Thursday, October 11, 2018

Chocolate Ice Cream Addendum

With Michel Cluizel Plantation Los Anconès Chocolate
I made another batch with the recipe from the last post, this time with Michel Cluizel Plantation Los Anconès chocolate, along with the Cluizel cocoa powder. This was an intense trip. I've always loved this chocolate, but never knew quite what to do with it, besides, of course, just eating it. It has an unusual and intense flavor profile, full of wood and liquorice and dark fruits and green olives. Please trust me that this is better than it sounds. It's rather magical, actually, although I've thought it might be a little overwhelming to people in large quantities in desserts. It's one thing to know you've just bought an expensive and unusual candy bar; it's another thing to be blindsided at the dinner table.

The verdict? I like it. Better than any chocolate ice cream I've had before. Your mileage may vary. The origin flavor is muted somewhat by the cocoa powder, which provides a less three-dimensional, straight-ahead intensity. The olives and wood and smoke and spices are present, but not much fruit. The flavor is complex. It's dark. 

I want more. If they ever make a Los Anconès cocoa powder, I'd love to try this origin undiluted. 

Temperature Notes

With this or any ice cream made with real chocolate, pay close attention to serving temperature. Let it warm up to the point that it feels soft against the edge of a spoon before serving. If the ice cream's near freezer temperatures, the cocoa butter will take too long to melt in the mouth and you'll get slow flavor release. This means muted flavors, and the impression of a watery melt. Which is a shame, considering there's over $8 US chocolate in a quart of this stuff, and that's when you buy by the kilogram. If you want your guests to taste an explosion of chocolate, and to experience a rich and creamy melt, slow down and let the ice cream soften all the way through.  

Cocoa Butter Tempering


Here's a thought worth exploring. If you've ever used chocolate for enrobing or candy making, you're familiar with the idea of tempering—a process of timed heat treatment used to produce chocolate with a shiny, dry finish and a melting point that's close to body temperature. If you melt chocolate and let it harden on its own, you get something much different from this. 

What's going on here? Cocoa butter, which provides the solid structure of chocolate, can in exist in any of five crystalline states called polymorphs or "forms," each with different melting points and other qualities.



Form V. is what chocolatiers aim for. We're not looking for gloss and snap in ice cream; we're looking for the softest, fastest melting cocoa butter. With gradual cooling of the ice cream mix after cooking, we probably get Form IV. This has the advantage of melting point over 6°C lower than that of a chocolate bar.

But if we chill the hot mix rapidly in an ice water bath (which should be standard practice, but can be challenging with large quantities) the cocoa butter may crystalize into Form I or II, with a significantly lower melting point?

I don't know if this will make any difference in an ice cream recipe. Cocoa butter behaves differently when it's in a simple dispersion with cocoa solids than when it's in a more complex emulsion or blended with other fats. I'm presenting this information because I haven't seen it addressed elsewhere. If you know anything, or if you're interested in experimenting, please get in touch. 




Part 1 of this series: Introduction
Part 2 of this series: Components
Part 3 of this series: How to Build a Recipe
Part 4 of this series: Basic Recipe Examples
Part 5 of this series: Techniques
Part 6 of this series: Sugars
Part 7 of this series: Stabilizers
Part 8 of this series: Emulsifiers
Part 9 of this series: Booze
Part 10 of this series: Solids, Water, Ice
Part 11 of this series: Introduction to Flavor
Part 12 of this series: Ice Cream Flavor: Coffee
Part 14 of this series: Chocolate Ice Cream
Part 15 of this series: Chocolate Ice Cream Addendum


Tuesday, September 25, 2018

Ice Cream Flavor: Chocolate

Cocoa Farm. Courtesy of knowingfarms.com



Welcome to our second deep-dive into flavor. I’ve had more requests for chocolate than for all others put together, and I’m not surprised. Who doesn’t love it? And who hasn’t had problems with it? Chocolate’s up there with coffee when it comes to technical challenges, but it presents its own unique vexations. 

Chocolate also resembles coffee in that it’s become more like wine over the last decades, with the emergence of small artisanal producers, the availability of single origins, and a growing appreciation for its astonishing range of flavors. As with wine and coffee, these flavors are the product of different growing regions, different varietals, and different processing methods. The interplay of genetics, terroir, aging, and fermentation have led to complexities that science has barely begun to decipher. 

This makes our investigations more complicated, as well as more interesting. Not so many years ago, a pastry chef could confidently say that brand x was the best chocolate. Today the question doesn’t even make sense. Best how? What flavors do you want? What textures? What other qualities? And how could you even sample all the chocolates that might be contenders?

We’ll discuss selecting chocolate a bit later. First let’s look at the basic challenges of making ice cream with good texture and a depth of chocolate flavors. If you

The Problems


With coffee, we faced the difficulties of extracting all of a great coffee bean’s flavors into the dairy. This isn’t a big deal with chocolate—you don’t even need to extract anything; just throw the chocolate into the mix. And chocolate’s flavors play well with sugar and dairy, and can handle a fair amount of dilution before the more subtle elements get obscured. 

But getting the texture right with chocolate can be a bitch.

More specifically, if you want great chocolate flavor, with impressive intensity, it’s challenging to also get good texture. The culprit is cocoa butter, which typically makes up half or more of the cocoa mass. 100 grams of unsweetened chocolate will contain 50 to 60 grams cocoa butter. 100 grams of 70% bittersweet chocolate will contain 35 to 40 grams cocoa butter. Unlike milk fat, cocoa butter is solid at room temperature, and hard as a rock at freezer temperatures. Generally speaking, your ice cream’s texture will be better with less cocoa butter, and best with close to none.

One way to accomplish this is to just use less chocolate. But f this seems like a reasonable solution, you and I have nothing more to discuss. Please get out of my kitchen. 

Another solution is to replace the couverture chocolate with cocoa powder. Cocoa is generally 10% to 20% cocoa butter—radically lower than chocolate. The trouble is that great quality, distinctive cocoa powder is still a rarity. Even the best manufacturers, like Valrhona, Amedei, and Michel Cluizel, typcially make cocoa powder as a byproduct of cocoa butter production, and so pay little attention to origin or distinctiveness. These companies make dozens of varieties of single-origin couverture but will typically offer just one or two fairly generic cocoa powders. 

There are a few exceptions. At least one large chocolate producer, Callebaut / Bensdof, offers a range of five single origin cocoas. But they don’t distribute these widely or sell at retail. There are a handful of smaller artisanal producers, some of which have a good reputation, but they don’t have the milling equipment to produce a fine powder; their cocoas will give ice cream a gritty consistency. 

This is a shame. As with coffee, my interest has been in bringing out the most interesting and compelling flavors that chocolate has to offer. And to do so without any textural compromises. I believe that ultimately the solution will be found in top-quality single-origin cocoa powders, but we may have to wait for the industry to catch up and make this pursuit practical. 

Our Solutions


I’ve formulated two recipes. One is a pure cocoa powder recipe that I’ll start testing when I find some worthy cocoa powder. The other is for right now, and represents a compromise—it gives the best chocolate flavor I’ve been able to manage without ruining the texture. This recipe uses a mix of couverture and cocoa powder. Let’s call it “double origin.” I don’t think most people will think it tastes compromised; so far it’s the best chocolate ice cream I’ve had. But I believe it falls short of what's theoretically possible.

Here are some principles behind the "double origin" formula:

1. 90g / L single origin dark chocolate. Tested with Michel Cluizel Vila Gracinda (67% cocoa solids). This is the highest quantity before I start to see texture problems.
2. 70g / L cocoa powder
3. reduced cream to milk ratio, to keep total fat level at 15%
4. no eggs
5. 14% total sugar. This is typical for most ice creams, but is much higher than my usual 11% level. Added sweetness compensates for the bitterness of cocoa. 
6. larger proportion of dextrose and fructose, to counter the hardening effect of the cocoa butter
7. reduced nonfat dry milk, to compensate for the added solids from the cocoa and chocolate
8. increase in guar and carrageenan, to compensate for the lack of thickening from the egg yolks
9. added lecithin, to compensate for the lack of emulsifier from the egg yolks
10. increased cooking temperature, to help hydrate the lecithin


Recipe 1: "Double Origin" Chocolate Ice Cream


440g (1 cup 6 oz) whole milk

70g  cocoa powder (must be best quality or don’t bother. tested with Michel Cluizel. Valrhona and Pernigotti/ChefShop should be good too)
70g dextrose powder 
25g sugar
20g fructose*
30g nonfat dry milk

2g soy lecithin
1.2g salt
0.8g locust bean gum
0.6g guar gum
0.4g lambda carrageenan


90g (3 oz) bittersweet chocolate (67–72% cocoa solids, chopped 
         (must be very high quality. tested Michel Cluizel Vila Gracinda 67%)

240g (1 cup) heavy cream
10g vanilla extract

*or use 45g trimoline and decrease dextrose to 50g. add trimoline after blending solids.

*******

-set circulator to 80°C / 176°F
-thoroughly mix the dry ingredients (not the chocolate)

-measure milk into blender.
-turn on blender to lowest speed that makes a vortex. pour in dry ingredients.
-blend on high for one minute.
-add chocolate. blend on high until incorporated—probably 2 minutes to melt and emulsify chocolate.

-Add cream, trimoline (if using), and vanilla extract. Blend briefly.

-pour mixture into 1gal ziplock bag.
-add weight (recommended, to keep bag from floating) and evacuate the air.
-cook in water bath for 45 minutes to hydrate stabilizers and partially denature milk proteins.
-gently agitate bag after 5 and 10 minutes. if you see air accumulated in the bag after 15 minutes, release it, and carefully reseal bag.
-mix will be pasteurized (pasteurization time after reaching this temperature is under 2 minutes).

-remove bag from water bath. open and pour hot mix into clean blender container (or a square container if using a homogenizer or stick blender). remove weight (with tongs). use bag to squeegie off any mix. temporarily seal bag and keep handy. 
-blend on highest speed for 60 seconds to homogenize. 

-chill bag in ice water bath (use ice bath to evacuate the air when sealing bag). carefully agitate to cool. Try to cool to refrigerator temperature. 
-refrigerate at least 8 hours, below 38°F / 3°C to age mix / pre-crystalize fat.

******
-snip off bottom corner of bag, and squeeze out mix as if using a pastry bag, into an open container (1.5L mixing bowl is ideal). mix will have formed a stiff gel from the emulsified and hardened cocoa butter. blend with a stick blender to thin texture (a whisk attachment will work best). 
-scrape into ice cream machine; spin. With a mulitispeed machine, use a slow setting. Ideal drawing temperature is 23°F / -5°C or below.
-evaluate when surface texture of ice cream first looks dry. if it needs more overrun, continue on higher speed. if it needs to cool more, continue on lower speed. 

-harden for several hours (preferably overnight) in a cold freezer. freezer should be set to -5°F / -20°C or lower. Ice cream will have to warm up several degrees before serving. 20 to 30 minutes in the fridge works well. Ideal serving temperature is 6 to 10° F / -14 to -12°C.


Total mass: 1000g
Milk Fat: 102g / 10%
Cocoa Butter: 44g? / ≤5%
Total fat: 146g? / 15%
Cocoa Solids Nonfat: 86g / 9%
nonfat milk solids: 82g / 8%
sugars (non-milk, non-chocolate) 104g / 10%
chocolate sugars (sucrose?) 30g / 3%
total sugars (non-milk) 144g /14%
total solids nonfat 312g / 31%
total solids: 458g / 46%
stabilizer 0.18%
emulsifier 0.2%

Tasting notes: I think this succeeds at presenting as a dark chocolate, rather than a milk chocolate, with little sense of anything between you and the chocolate itself. However, the flavor of the cocoa powder outweighs the flavor of the couverture by around 2 to 1.  You can still taste the single-origin chocolate, but the flavor of the cocoa powder is the limiting factor here. 

**********


Onto the single-origin cocoa recipe. When we can get our hands on the right cocoa powders, this will take us close to what's possible with chocolate ice cream.

Here are differences from the “double origin” version:

1. more cocoa, no chocolate
2. higher milk to cream ratio, since there’s less cocoa butter to compensate for
3. closer to normal levels of dextrose and fructose, since there’s less cocoa butter to compensate for

Recipe 2: Single Origin Cocoa Ice Cream

395g (1 cup 5.25 oz) whole milk

110g  single-origin cocoa powder, best quality (very hard to find. ideally use non-Dutch process, which is even harder to find. Recipe assumes 15–20% cocoa butter content)
80g sugar
50g dextrose powder 
12g fructose*
30g nonfat dry milk

2g soy lecithin
1.2g salt
0.8g locust bean gum
0.6g guar gum
0.4g lambda carrageenan

310g (1 cup 2.5 oz) heavy cream
10g vanilla extract

*or use 30g trimoline and decrease dextrose to 38g. add trimoline after blending solids.

*******

-set circulator to 80°C / 176°F
-thoroughly mix the dry ingredients (not the chocolate)

-measure milk into blender.
-turn on blender to lowest speed that makes a vortex. pour in dry ingredients.
-blend on high for one minute.

-Add cream, trimoline (if using), and vanilla extract. Blend briefly.

-pour mixture into 1gal ziplock bag.
-add weight (recommended, to keep bag from floating) and evacuate the air.
-cook in water bath for 45 minutes to hydrate stabilizers and partially denature milk proteins.
-gently agitate bag after 5 and 10 minutes. if you see air accumulated in the bag after 15 minutes, release it, and carefully reseal bag.
-mix will be pasteurized (pasteurization time after reaching this temperature is under 2 minutes).

-remove bag from water bath. open and pour hot mix into clean blender container (or a square container if using a homogenizer or stick blender). remove weight (with tongs). use bag to squeegie off any mix. temporarily seal bag and keep handy. 
-blend on highest speed for 60 seconds to homogenize. 

-chill bag in ice water bath (use ice bath to evacuate the air when sealing bag). carefully agitate to cool. Try to cool to refrigerator temperature. 
-refrigerate at least 8 hours, below 38°F / 3°C to age mix / pre-crystalize fat.

******
-snip off bottom corner of bag, and squeeze out mix as if using a pastry bag, into an open container (1.5L mixing bowl is ideal). mix will have formed a stiff gel from the emulsified and hardened cocoa butter. blend with a stick blender to thin texture (a whisk attachment will work best). 
-scrape into ice cream machine; spin. With a mulitispeed machine, use a slow setting. Ideal drawing temperature is 23°F / -5°C or below.
-evaluate when surface texture of ice cream first looks dry. if it needs more overrun, continue on higher speed. if it needs to cool more, continue on lower speed. 

-harden for several hours (preferably overnight) in a cold freezer. freezer should be set to -5°F / -20°C or lower. Ice cream will have to warm up several degrees before serving. 20 to 30 minutes in the fridge works well. Ideal serving temperature is 6 to 10° F / -14 to -12°C.


Total mass: 1002g
Milk Fat: 126g / 12.5%
Cocoa Butter: 22g? / ≤5%
Total fat: 148g? / 15%
Cocoa Solids Nonfat: 88g / 9%
nonfat milk solids: 82g / 8%
total sugars (non-milk) 142g /14%
total solids nonfat: 312g / 31%
total solids: 460g / 46%
stabilizer 0.18%
emulsifier 0.2%



Appendix 1. Some Chocolate Basics

Cocoa beans fresh out of the roaster. Thanks to Michael Laiskonis at the ICE Chocolate Lab.


Cocoa % or cocoa solids %: In plain chocolates—unflavored and non-milk chocolates—this refers to everything besides sugar. It's the cocoa mass from the cocoa pod. It will be very roughly half cocoa, half cocoa butter. So a 70% dark chocolate will be about 35% cocoa, 35% cocoa butter, 30% sugar. With some chocolates the cocoa butter can be as high as 60 or 65%. And with some specialty chocolates it can be as low as 45%. The best chocolate producers publish this information, so you don't have to guess at what you're working with. 

Do not assume that higher cocoa % is always better. The best chocolate producers are striving for balance; they're not chasing numbers. The best chocolates I've ever had have been around 67%. I've had some lousy 85% bars. 


Origins: I haven't written a tasting guide to the different regions because I just don't know enough. And I suspect it would be pointless. There is so much variation from one small producer to another that the generalizations just don't hold up very well. 

When it comes to sheer pleasure and interest, though, I can easily say that the best chocolates I've had have been single origins. This term is surprisingly difficult to define. Does it mean from a single farm? A single Cooperative? A single region? A single country?

As with coffee, the precise definition varies from one place to the next. While there may be cases where the term is used in bad faith, by marketers who want to sell you a cheap blend, I've never had this experience with a quality chocolate maker. The better single origins taste like a distinctive expression of ... something. Whether it's a hillside, a region, or a nation seems less important. 


Cocoa Powder Types: "Dutch" process cocoas are treated with an alkali, which alters the appearance and flavor. Dutched powders will be a darker, richer red, but the flavor will be milder, with less bitterness and astringency. Since dairy and sugar both take the edge off of chocolate's flavors, you may find you can get a more intense flavor experience from natural process cocoas. 

That is, if all else is equal. Which it never is. Most European cocoas are only available as Dutch process. The quality of the individual powder is more important than any theoretical difference in its processing method. 

In baking, the distinction is important; if you switch between Dutch and natural, you'll change the pH, and will often have to compensate with changes to your leavening ingredients. This is one area where ice cream is more forgiving. We only worry about about the fat and the flavor. 

Which brings us to the fat: check the cocoa butter percentage. Cocoa usually has more than you'd expect, and the high-end brands (annoyingly) usually have the most. Be prepared to compensate for high fat levels. 



Appendix 1. Chocolate Variety Tasting Notes


Similar to the Coffee Wheel. Courtesy Barry Callebaut


The Chocolate industry divides cocoa trees into three major species:

Criollo

Criollo cocoa beans account for less than 5% of the world’s production, due to their succeptibility to numerous blights. Partly because of its rarity, and partly because of its delicate flavor profile (which emphasizes fruit and other long-lingering secondary flavors over the more bitter and and astringent baseline chocolate notes) it’s considered a delicacy. Most blends that include criollo use it in small proportions. 

Criollo is native to Central and South America, and the Caribbean island of Sri Lanka. Subspecies include Andino, Pentagana, and Porcelana.

Forestero

Much more robust than Criollo, Forastero cocoa comprises over 80% of the world’s production. It has strong bitter notes, basic chocolate flavor, and fewer of the fruity and acidic top notes than the other varieties. It tends to come on strong and have a short finish.

Forastero cocoa is native to the Amazon basin, and today is grown in Ecuador, Brazil, and much of equatorial Africa. Subspecies include Amelonado, Arriba, Cundeamor, and Calabacillo. While Forestero’s reputation is as a commodity chocolate, some subspecies and some farms present exquisite examples. Michel Cluizel’s Vila Gracinda, one of my favorite culinary chocolates, is 100% Amenolado.

Trinitario

Trinitario is a hybrid of Criollo and Forastero varieties, attempting to merge delicacy of the former with the robustness of the latter. 

Trinitario is believed to have origninated in Trinidad, and is now grown in Mexico, the Caribbean, Colombia, Venezuela, and Southeast Asia. It’s a dominant componant in many fine chocolates. 

In Conclusion

Rather than a conclusion, this appendix gets a refutation: almost everything I’ve written about these cocoa varieties is bullshit. I had to include it, because it’s the conventional industry knowledge, and without it information you won’t know what anyone's talking about.

But nevertheless, it's mostly nonsense. Modern genetic testing tells us that there aren’t three cocoa varieties; there are at least eleven. They get grouped as three based on superficial resemblance, geographical accident, and lore. Most growers are dealing in hybrids, and genetically speaking, have no idea what the provenance of their trees might be.

Which is ok, if your not a botanist or agricultural anthropologist. Don’t worry about the labels. Worry about flavor. There are some fine chocolate review sites for the unfortunate instances when you can’t manage to taste everything yourself (see below). 

For further reading:



Appendix 2. Chocolate Review Sites





Appendix 3. Where to buy Chocolate



Worldwied Chocolate
(Their shipping prices for small quantities have become insulting.)




Appendix 4. The Future: Single Origin Cocoa Powders

Bensdorp / Callebaut Natural Process São Tomé

Bensdorp / Callebaut 



(Tanzania)


(Ecuador)


(Ghana)


(Honduras)


(Several origins)



And some halfway-there althernatives: Low Cocoa Butter Couvertures:





Part 1 of this series: Introduction
Part 2 of this series: Components
Part 3 of this series: How to Build a Recipe
Part 4 of this series: Basic Recipe Examples
Part 5 of this series: Techniques
Part 6 of this series: Sugars
Part 7 of this series: Stabilizers
Part 8 of this series: Emulsifiers
Part 9 of this series: Booze
Part 10 of this series: Solids, Water, Ice
Part 11 of this series: Introduction to Flavor
Part 12 of this series: Ice Cream Flavor: Coffee
Part 14 of this series: Chocolate Ice Cream
Part 15 of this series: Chocolate Ice Cream Addendum




Thursday, April 26, 2018

Coffee Ice Cream Addendum: Origin Notes and Minutiae

Farmland in Banga, Burundi. Photo by Christine Vaufrey. From dailycoffeenews.com


The coffee ice cream method described in the previous post has been so successful at preserving the origin character of coffee that it's turned into a minor fetish. I can't stop making batches with different coffees, and eating them, which is getting me into some trouble with my girlfriend, who turns lycanthropic from caffeine past noon.

A couple of Tuesdays ago, mid-fetish, when she kicked me out of the house suggested that I work remotely, I stopped by our local espresso bar, Coffee Mob. This place just happens to be my favorite roaster in the city, even inching out some of the heavy hitters from the West Coast. The barista pulled me a shot of the Burundian natural process they had on tap that day. Holy god was it good—syrupy, sweet, caramely, floral, and then ... an explosion of blackberries. I'd never tasted anything quite like it. I was just picking myself off the floor when the owner, Buck, walked in.

I told him it was the best shot I'd had in the last 6 months—and I'd been to Stumptown and Toby's Estate just in the last week.

"Why don't you come back at 6:30 tonight," He said. "The producer's giving a talk."

So I came back, and listened to Ben from Long Miles Coffee tell the story of his journey into coffee production in Burundi, in the middle of a rising dictatorship, impoverished farmers, and some of the best coffee in the world. His family built a washing station for the farmers on three neighboring hills, and made a commitment to paying the farmers fairly and on-time ... a departure from the status quo in the region.

I brought something for the afterparty—a half-pint of ice cream, made with Stumptown's Ethiopia Duromina, a perennial favorite. This coffee sings through the dairy with notes of cocoa, caramel, and blood oranges. Buck said he tasted the coffee through the ice cream in a way he never had before. Ben just ate the rest of it.

I had a chance to try an espresso made with Long Miles' latest batch of honey-process beans (a hybrid of washed and natural-process), which was delicious in an unusual way (a dark fruit flavor that was almost familiar), but I couldn't stop thinking about that natural-process blackberry bomb. Buck gave me 100 grams of it try in the next batch of ice cream.

Long Miles Burundi Gishubi Natural Process, roasted to perfection by Coffee Mob.

I was a little concerned that this coffee might be too distinctive—too weird—for ice cream.  Some experienced coffee tasters are wary of dry-process coffees with too strong a fruit flavor. Such coffees can come off as one-note, or even a bit like artificial fruit candy.* And even if the flavor's balanced, sometimes the more distinctive ones aren't appropriate for everything. The first time I tasted Michel Cluizel's Los Ancones single-origin chocolate, I thought: 1. this is one of the best things I've ever had, and 2. I have no idea what to do with it—besides just eat it as it is. Because it tastes like liquorice and olives. It's surprising and wonderful as a self-contained experience, but may make people wince in an ice cream or cake.

This time my worries were unfounded. The ice cream was unique and addictive. Chocolate blackberry, caramel blackberry, blackberry jam. I almost borrowed a Blackberry to write this post. I'm now tempted—and almost dorky enough—to serve multiple regions of coffee ice cream together, maybe each in its own demitasse. I'm thinking Ethiopia, Burundi, and possibly an Indonesian or Sumatran. Like the tired convention of serving something "three ways," but in this case three wheres.


Straight out of the machine. Earth tones belie the blackberry bomb within.
Residence time 7.5 minutes, drawing temperature -6°C. Smoooooth.

Miscellaneous Process Notes

I've never monitored the temperature / time curve of the ice cream mix in the sous-vide bath, because I don't have the kinds of lab equipment that make this easy. I have software for predicting the rate of temperature increase for a steak or fish fillet in a water bath, but doing so for an amorphous bag of viscous fluid is beyond my art.

My wild educated guess was that with a bit of agitation, and with help from convection currents in the ice cream mix, it would take 15 to 20 minutes for the mix to get to 75°C, where it would then remain for a half hour. This last week I decided to test this hypothesis manually, by interrupting the process a few times up until the end and taking a temperature reading.

The hypothesis was way off. The temperature rose much more slowly than I'd expected, was not impressively sped along by my early agitations, and never reached 75°C. This means that at least some portion of the locust bean gum has not been getting hydrated. It also means that the conditions for partial milk protein denaturing have not been what I'd assumed—although the exact expected effects of this are too complex and poorly understood to make any guesses about.

I came up with a quick fix, based on an armchair-understanding of thermodynamics. Knowing that the biggest factor in speed of heating is the temperature difference between the cooking environment and the current food temperature (Delta-T), it made sense to start in a hotter water bath. The trick is to try to heat the mix quickly, but not overshoot by too much. Ideally, you'd let a PID controller take over, like the one that so efficiently gets the water bath to a precise temperature and holds it there. For better or worse, you're not supposed to circulate ice cream mix directly with an immersion circulator. Until someone makes an affordable circulator that works with a probe stuck directly in the food, we're stuck with more primitive methods.**

My first experiment has been to split the cook into two stages. 30 minutes at 85°C, then 30 minutes at 75°C, with the water bath uncovered, so it will cool at a reasonable rate. I haven't charted the temperature / time curve, but the result was clearly different. The ice cream has more body when frozen, and has resisted developing ice crystals in the freezer for two weeks ... several days longer than what I'm used to.

I'd like to do a few more experiments with cooking time and temperatures. This may lead me to updating the sous-vide instructions, and possibly even the stabilizer blends, for all the recipes in this series.

There are all kinds of variables at play here, which will make absolute precision and predictability impossible. This raises the question of why to use an immersion circulator at all. I believe it makes sense, because 1. it's hands-off, and once the temperature stabilizes at or near your target, it will stay there precisely, and 2. cooking in sealed environment is great for preserving aromatic flavors.


Anatomy of a coffee cherry. From mishasmundi.com.




*when you taste odd fruits in coffee or wine—something besides coffee or grapes— you're generally tasting an aromatic compound that also exists in that fruit. But you're not tasting ALL the aromatic compounds from that fruit. If the compound is in the coffee/wine in small quantities, you get a nice hint of blackberries (or whatever) that blends intriguingly with other flavors. But if  there's a ton of that compound, you may be reminded of other foods foods that include a ton of that single flavor compound, isolated from all the fruit's background flavor compounds—think of a Jolly Rancher, or Fruit Roll-Up, or Instant Jell-O. Maybe not what you want in your coffee.

How do these compounds end up in coffee or wine? Usually they're either products of fermentation, maillard reactions from cooking (coffee), or barrel aging (wine). All three of these processes convert simple chemicals into a symphony of complex compounds, with more variables than science has yet been able to wrap its big head around.

**A laboratory hot plate with a magnetic stirrer may be useful for this. I'm waiting for someone to make one specifically for culinary use. The Breville/PolyScience Control Freak is a nod in the right direction, but it doesn't stir, and it costs $1800. The much-ballyhooed Instant Pot may be a decent low-budget solution for moderate volumes and home use, but it likewise doesn't stir. The much-loved Thermomix is finally available in the US. This may be an ideal solution for small quantities. Not cheap at $1400+ but people use them for everything. For commercial quantities, a pasteurizer and a connected chiller are the way to go.


Part 1 of this series: Introduction
Part 2 of this series: Components
Part 3 of this series: How to Build a Recipe
Part 4 of this series: Basic Recipe Examples
Part 5 of this series: Techniques
Part 6 of this series: Sugars
Part 7 of this series: Stabilizers
Part 8 of this series: Emulsifiers
Part 9 of this series: Booze
Part 10 of this series: Solids, Water, Ice
Part 11 of this series: Introduction to Flavor
Part 12 of this series: Ice Cream Flavor: Coffee
Part 14 of this series: Chocolate Ice Cream
Part 15 of this series: Chocolate Ice Cream Addendum







Tuesday, February 27, 2018

Ice Cream Flavor: Coffee



Welcome to the first post that focusses on a single flavor. We’re starting with coffee, not because it’s simple—it’s maybe the most complex flavor we’ll have the pleasure of disecting. We’re going to take on this complexity because coffee flavor illustrates so many principles, and because there’s a mountain of high quality research already available, at least with regards to making a cup of joe. 

To make good coffee ice cream you do have to learn to make good coffee. If this were a simple task, everyone would be doing it. Everyone is not doing it. I lived in New York City for about 15 years before having my first truly good cup. Coffee’s 3rd wave took a couple of decades to make it all the way East from Portland and Seattle, and is only just now gaining traction in a culture that’s been long-steeped in the bitter seas of Starbucks, and before that, street-cart swill and Café Bustello.

Good coffee starts with sourcing high-quality beans that are roasted with precision and that have whatever characteristics you most enjoy. Differences in regional varieties and processing methods are beyond our scope here. See the links at the bottom for suggested reading. 

Roasting, however, is of primary importance and needs to be considered. Roasting coffee well is hard. I’ve bought coffee beans from many local, supposedly artisanal roasters, and have usually been disappointed. Sometimes the roasters just have terrible ideas about coffee. Many of these ideas were propagated by Starbucks and other 2nd wave roasters—like the idea that dark-roasted coffee is somehow “bolder” or more serious than light and medium roasts. Dark-roasted coffee is, more often than not, ruined coffee. Once you inch past a full-city (medium-darkish) roast, the aromatic flavors that distinguish good beans from bad ones, and one region from another, are muted, replaced by generic roasted flavors. Roast  darker still and those origin flavors are demolished entirely, replaced by burnt flavors and bitter non-volatile chemicals. 

Selling us on dark roasts was a cynical ploy by companies like Starbucks, who figured out that 1) if you roast the coffee dark, your customers won’t be able to tell the difference between good beans and bad, from this region or that one, from beans harvested this season or last. So quality and consistency become non-issues. And 2) if you roast the coffee dark, it will be bitter, and people will want to tame it with sugar and milk. Which means that instead of selling $1 coffees or $3 espressos, you can sell $5 lattés and skim-mocha frapuccinos and other coffee-flavored sundaes that can survive bad ingredients and poor technique, and, (bonus!) will let you to mark up milk for a 1000% profit. 

Even roasters who attempt proper degrees of roasting often mess up. Because the process is much more complex and sensitive to precise timing and energy-input modulation than, say, baking bread or popping popcorn. And it's easy to let portions of some of the beans roast more than others. This may lead to coffee that has the overall color and aroma of a proper roast, but upon closer examination will have spots that glisten with oils brought to the surface. The resulting coffee will typically have the basic character of a light or medium roast, but will have burnt / bitter background notes that will always be out of balance. Every attempt at a light or medium-roast coffee I’ve bought from Whole Foods’ in-house roaster has suffered from this. Same with coffee bought from most small shops that roast their own. In the end, looking at the beans only gets you so far. To know for sure you have to taste the coffee.

Not living in the Pacific Northwest, I’ve been limited to a handful 3rd wave companies who have built outposts here, and to a very small number of local roasters who know what they’re doing. 





Some of the nationally-distributed roasters that I like:
-Stumptown (Portland / NYC)
-Intelligentsia (Chicago)
-Toby’s Estate (Australia)

Some NYC roasters that get it right:
-9th St. Espresso
-Joe the Art of Coffee
-Coffee Mob (in my neighborhood. The only mom ’n pop shop I’ve been to that roasts like a boss).

I like to buy single-origin beans, because they're usually the most interesting. Even with espresso (a glorious topic that lies well beyond our scope, because the espresso process doesn’t lend itself to ice cream) baristas have figured out how to work with single origin beans, which were previously believed to be too full of character and fruity acidity to make a balanced shot. Nowadays there’s less reason than in the past to fall back on blends.

I also like to look for direct trade arrangements between the roaster and the plantation. Coffee has historically been rife with colonial exploitation, so it’s gratifying to see roasters working with individual farmers and cooperatives, ocassionally even investing in their operations and helping the farmers achieve prosperity and independence.

My dream coffee is generally from East Africa, especially Ethiopia, where coffees often offer a magical balance of syrupy body, earthy undertones, fruity acidity, and floral or herbal aromas. I like a lot of flavor in my cup. 

People who don’t want so much flavor generally tame their coffee with milk and sugar. I do not, unless the coffee is bad, or I’m enjoying a morning capuccino (which is a whole ‘nuther topic). This introduces the basic problem of coffee ice cream—there’s going to be a lot of milk and sugar. Because it’s ice cream. So if you want those coffee flavors to stand up, you’re going to have to put a lot of them in there to begin with, especially the acidic and aromatic flavors that will be most muted. We’ll get to this.

But first—how to make a good cup of Joe?


Brewing coffee is an extraction process. We’re extracting literally hundreds of compounds from the coffee beans, including the basic sugars, acids, and alkaloids that constitute the heavy molecules detected by our taste buds, and also the myriad volatile organic compounds that we detect with our nose. There are other compounds that we either don’t want, or that we want in minute quantities. And among the ones that we do want, we want them in proportions that taste balanced and satisfying. And we want the overall flavor to be strong enough. But not too strong. 

How do you do all that? Happily, there’s science on the topic. Which means that some very patient men and women with PhDs have done much of the work for us. Here’s a chart from the Specialty Coffee Association of America:



There’s a lot of information here for a 2-dimensional chart. Allow me to summarize. The two axes represent strength (vertical axis) and solubles yield, or extraction (horizontal axis). 

Strength is simply the amount of coffee solids disolved in the brewing water, represented as a percentage of the water weight. More = stronger. 

Solubles yield is what percentage of the available soluble stuff you've drawn out of the beans. Brewing for a longer time, or with a finer grind (which exposes more surface area) gives more extraction.

If you extract too little, you have an “undeveloped” cup, which is typically sour and thin. If you extract too much, the coffee becomes bitter.

The diagonal red lines are each for a brewing ratio, which is the actual ratio of coffee beans to water. The lines are diagonal because as you brew longer, or hotter, both strength and extraction of the coffee increase. You control these variables independently by choosing different brewing ratios.

For both strength and extraction, there’s a sweet spot, represented by the orange square in the middle. According to the chart, you can get into that zone with any brewing ratio between 3.25 and 4.25 oz / half gallon. Or, if you prefer units that aren't preposterous, between 4.8% and 6.3% relative to the weight of the water.

Without a refractometer or hydrometer, it will difficult to follow this chart precisely. And there’s no need to. Use the chart as a model, to help you understand what you’re tasting, and which variables you need to change when trying to adjust the flavors. If your ideal cup doesn't land precisely in that square, who cares.

The chart does not address the specific factors that determine extraction, which are time, temperature, and grind size. Time and grind size are bound together; the coarser the grind, the more time you need to get to a particular level of extraction. Many coffee making methods determine the general grind size. Press pots require a coarse grind (and so a long brew time) otherwise you'll clog the filter. Espresso requires a very fine and consistent grind. Drip and pourover coffees cede the control of time to gravity and physics, so you have to find a grind size that works with the time you're given. See notes on grinding, below.

Temperature is also critical. It affects extraction rate, but does not affect all flavor compounds equally. So brewing temperature is an important variable for adjusting the flavor balance. The generally accepted range of brewing temperatures is  90°C–96°C / 195–205°F. 

Within this range, higher temperatures will give more extraction, more body, more sweetness, more bitterness, and less acidity. Lower temperatures, or course, will give thinner body, more acidity, less bitterness, and less sweetness. Based on my personal experiments, I brew French press coffee at 93°C / 199°F. I use a higher temperature for coffee ice cream. More on that later.

What about cold brew? I've now had some good-tasting examples, but more often than not find that it's pretty dull. I believe it’s popular because people are accustomed to bad coffee that tastes burnt and bitter. Cold brew extracts fewer bitter alkaloids from the bean, so without any special skill or even decent quality beans, you can entirely avoid bitterness. But cold brew also results in reduced acidity and aromatics—there’s less there there. More bass notes and roasted flavors. Coffee shops have turned “low acidity” into a feature, not a bug, because consumers don’t know what acidity is. It sounds scary, and is easy to conflate with bitterness, even though it’s essential to a balanced and lively cup. Acidity and bitterness, in fact, have a reciprocal relationship in hot-brewed coffee. More of one leads to less of the other. 

When making coffee ice cream, we’re interested in increasing acidity and aromatics, not decreasing them. We need to try to punch through the heavy muting tendencies of the dairy and sugar. 



Notes on grinding: If you want good coffee, you need a good burr grinder. This means a grinder with a hopper on top for beans, a set of conical or flat burs to grind the coffee, and a receptacle for grounds on the bottom. A whirly-blade grinder gives no consistency, so you are you are guaranteed some mix of coffee dust in with your grounds, which will over-extract and cause bitterness. If you’re just making brewed coffee and ice cream, any decent burr grinder will do. Entry-level grinders from Baratza will make as good a cup of brewed coffee as anything (if you’re making espresso—again, beyond our scope—you don’t need a good grinder; you need an awesome grinder. You will spend over $700 or you’re wasting your time. More reason to just go to the café). 

Your coffee needs to be fresh, meaning roasted between 4 and 10 days ago, stored in an airtight container at room temperature, and ground right before use. If you’re buying pre-ground coffee and letting it sit around for days, you’re sabotaging the process before you even begin.

A Coffee Recipe


For reference, here’s my idea of good coffee, scaled for a large French press pot:


-1400g filtered water
-80g–90g coffee. A good, fresh, light-to-medium roast. Medium-coarse ground, right before brewing (I don’t know how to measure grind precisely. I go a few clicks finer than the coarsest press pot setting. You’ll have to experiement) Concentration: 5.7%–6.4% by weight.

-preheat the press pot. pour in a few ounces of water just off the boil, swirl around and dump it out.
-put coffee grounds in prewarmed pot
-heat water to  93°C / 199°F (for some natural process coffees, I go as low as 90°C / 195°F)
-fill press pot about 3/4 full. start 4-minute timer.
-after 45 seconds, stir vigorously to break up the foam and raft of grounds on top. chopsticks or a palette knife work well.
-fill the rest of the way. cover.
-brew 4 minutes total. stirr again briefly. press the plunger.
-immediately drink or decant to cups / a prewarmed thermos.

Note on brewing methods: I use a press pot, because I like a lot of body, and because I like the control it gives over every variable. Many other brewing methods are capable of equally good, but different results. Some methods, like percolation, are not capable of good results. 

French press most closely resembles the process I’ll recommend for coffee ice cream, so it offers a good frame of reference.




Finally, Coffee Ice Cream


It took 21 versions to get this right. The goal was to preserve the full spectrum of flavors and aromas I get from a great cup of brewed coffee (like from the above method) or from a great cup of espresso, and to somehow have it complemented by, not demolshed by, the sugar and dairy of the ice cream. 


Some of the challenges:

  • The taste and aroma compounds in coffee have different levels of solubility in fats than in water. So the time / temperature / concentration guidelines that make the best coffee are not identical for ice cream
  • All brewing times / temperatures capable of extracting aromatics, fruity acids, and midrange roasted flavors into milk and cream also extract too much bitterness, possibly because of high carbon dioxide solubility
  • The aromatics in coffee are both muted by dairy and prone to evaporation during brewing and cooking


My solutions:

  • A lowfat base recipe, with milkfat around 10–11%
  • Less than the usual amount of sugar. Also 10–11%
  • A low proportion of eggs (2 yolks per liter), typical of most of my recipes
  • Additional nonfat milk solids, to preserve the full body of the ice cream
  • A high proportion of fresh-ground, high-quality, light-to-medium roast coffee (double the concentration used for brewed coffee in the method above)
  • A higher brew temperature, to increase extraction and help balance flavors
  • A modified brew method, in which the coffee and hot dairy are bloomed, then sealed in a ziploc bag while brewing, and chilled in ice water before straining, in order to preserve the aromatics
  • Added salt, to temper bitterness
  • Added acid, in the form of Pedro Ximenez sherry vinegar, to restore the balance of fruity acidity
  • Additional milk and cream, to compensate for what will be thrown out with the coffee grounds



Recipe: Underbelly Coffee Ice Cream


The recipe is written for cooking in an immersion circulator. It can be adapted to work with other methods, but a circulator is prefered for its ability to cook the mix in a fully sealed container that will preserve the aromatics. This makes about 1L of mix. About 180ml of milk and cream will be lost with the coffee grounds. [instructions edited 5-11-2018 for clarity.]

100g coffee beans (ideally light to medium-light roast, with full body and lots of fruit and acid. East African varieties are often ideal)

580g whole milk* (3.3% fat) divided 320g / 260g
320g  heavy cream* (36% fat) 

65g granulated sugar 
25g dextrose
15g trimoline**
90g nonfat dry milk*

2g salt 
1.4g preblended stabilizers, or: 
0.8g locust bean gum (tested with TIC Gums POR/A, soluble at 74°C)
0.4g guar gum
0.2g lambda carrageenan
        
2 large egg yolks (36g)
7g sherry vinegar*** (1.5tsp)


*Use the best quality milk and cream you can get. Nothing ultrapasteurized. Low-temperature pasteurized is ideal. Homogenized products will give best texture. Avoid cream with added stabilizer (unknown variables). Dry milk must be 100% skim milk solids, processed without high heat. There should be no off odors either when it's dry or when it's mixed. Store sealed in freezer.

**Or substitute 5g fructose powder, and add an additional 5g dextrose.

***Ideally use a Pedro Ximenez sherry vinegar, which has aged and savory notes that complement the midrange flavors of coffee. The darker the roast, or the lower the acidity of the coffee, the more vinegar will be useful to balance the flavors. adding (or partially substituting) citric acid  can help shift flavor to a brighter / sharper acidity. This may be helfpul if your coffee is lacking in high notes.


-set immersion circulator to 75°C / 167°F

start mixing base
-thoroughly mix powdered ingredients. use a 0.01g scale to measure salt and stabilizers.
-separate eggs and set yolks aside. freeze whites for other use.
-measure smaller portion of milk and trimoline into blender.
-set blender speed to create a vortex; add powdered ingredients. cover and blend on high for 30 seconds to disperse the stabilizers. 

prepare coffee infusion
-measure coffee beans and load burr grinder. set very coarse (like commercial breadcrumbs)
-prepare ice water bath
-prepare 1-gallon ziploc bag, set in a container that can hold it upright
-heat larger portion of milk and all cream on stovetop to 95°C / 203°F.
 (ideally use a relatively narrow vessel that’s easy to pour from and that minimizes evaporation. 
  you can use a metal pitcher set in a pot of boiling water)
-when cream/milk is nearly done heating, grind beans. pour grounds into the ziploc bag
-when milk/cream reaches temperature, pour just enough into bag to saturate the grounds. start timer set for 3 minutes 30 seconds.
-agitatate briefly and let the grounds sit with the bag unsealed.

-after 30 seconds add the remaing hot milk/ cream. push out as much air as possible and seal the bag.

strain coffee infusion and complete base
-set a fine chinois or strainer over the blender jar. cut the zip end off of the ziploc bag of coffee slurry and pour / squeeze it into the chinois
-let it strain for 10 minutes, periodically stirring / pushing on grounds with a rubber spatula to squeeze out as much infused liquid as possible
-add yolks and briefly blend
-add sherry vinegar and briefly blend again

-pour mixture into 1gal ziplock bag.
-add weight (recommended, to keep bag from floating) and evacuate the air.
-cook in water bath for 30 minutes to quickly raise temperature to 75°C / 167°F
-gently agitate bag after 15 minutes and 30 minutes. if you see air accumulated in the bag, release it, and carefully reseal bag.
-Drop circulator temperature to 75°C / 167°F. Uncover the container if was covered.
-cook in water bath an additional 30 minutes to set custard, hydrate stabilizers, denature milk proteins.
-mix will be pasteurized (pasteurization time after reaching this temperature is under 2 minutes).

-remove bag from water bath. open and pour hot mix into clean blender container (or a square container if using a homogenizer or stick blender). remove weight (with tongs). use bag to squeegee off any mix. temporarily seal bag and keep handy. 
-blend on highest speed for 30 seconds to homogenize.
-pour mix back into ziplock bag.

-chill bag in ice water bath (use ice bath to evacuate the air when sealing bag). carefully agitate to cool. Try to cool to refrigerator temperature. 

-refrigerate at least 8 hours, below 38°F / 3°C to age mix / pre-crystalize fat.

******
-pour into ice cream machine: snip off bottom corner of bag, and squeeze out mix as if using a pastry bag. or squeeze out into an intermediate container that’s easy to pour from.
-spin in the ice cream maker. With a mulitispeed machine, use a slow setting (this recipe works best with a low overrun). Ideal drawing temperature is 23°F / -5°C. Go lower if machine can do so without excessive extra time.
-evaluate when surface texture of ice cream first looks dry. if it needs more overrun, continue on higher speed. if it needs to cool more, continue on lower speed.

-harden for several hours (preferably overnight) in a cold freezer. freezer should be set to -5°F / -20°C or lower. Ice cream will have to warm up several degrees before serving. 20 to 30 minutes in the fridge works well. Ideal serving temperature is 6 to 10° F / -14 to -12°C.


Composition:

total mass before straining: 1141g
total mass after straining: 983g (assuming 22g / 22% coffee solubles yield)
milk after straining: 490g / 16g fat  / 43g solids nonfat
cream after straining: 230g / 83g fat / 13g soldis nonfat
total milk fat: 99g / 10% 
total fat: 117g / 12%
nonfat milk solids: 146g / 14.8%
total nonfat solids: 291g / 29.6%
total solids (fat + nonfat): 408g / 42%
egg fats: 9g / 1%
egg proteins: 6g / 0.6%
egg lecithin: 2.9g / 0.3%
total egg solids: 18g / 1.8%
sugars (non-lactose): 105g / 10.7%

stabilizers (non-egg): 1.4g / 0.14%


Experiment notes on coffee extraction methods:

-Commercial or homemade coffee extract, made with alcohol: basic coffee, roast, and bitter flavors. Flat. Little fruit or liveliness or lighter aromatics.

-"Instant" infusion into alcohol, made with whipping siphon and nitrous oxide: similar to conventional extract, but more mid-rangey and less bitter.

-Coffee infused into water, brewed as very strong coffee (typically press-pot style) and strained. Extra water compensated for by balancing recipe and adding milk solids: typical ice cream shop coffee ice cream flavors, emphasizing roast and base coffee notes. Brighter flavors and aromas muted.

-Coffee mixed into simmered milk or cream, brewed as it cools, for 10 to 30 minutes: standard coffee ice cream flavor. Fairly flat. Slighty bitter and overextracted tasting when brewed strong. Little fruit or aroma.

-Coffee brewed into ice cream mix in sous-vide bag as mix cooks, at 75°C for 45 minutes: Prominent fruit and aromatic flavors, but a strong, metalic bitter imballance.

-Coffee cold brewed into dairy overnight in fridge: Very weak relative to amount of coffee used. No bitterness, and likewise no acidity or aromatics. All midrange. Similar to instant coffee.

-Coffee brewed with dairy in sealed bag, then chilled in bag before straining (similar to Japanese iced coffee method). 75°C, 4 to 7 minutes: Good aromatics and acidity. Midrange flavors undeveloped. Metalic bitterness present and out of balance.

-Coffee brewed with dairy in sealed bag, then chilled in bag before straining. 93°C to 95°C, 4 to 7 minutes: Fairly well developed coffee flavors, including aromatics and acidity. Metalic bitterness still somewhat present and out of balance.

-Coffee brewed with dairy in sealed bag, then chilled in bag before straining. 96°C, 4 to 5 minutes: Fuller range, 3-dimensional, better balanced flavor. Still too much metalic bitterness.

-Coffee brewed with dairy in sealed bag, then chilled in bag before straining. 96°C, 3 minutes: Full range, 3-dimensional, well balanced. Only slight remaining metalic / bitter notes. Brought mostly into balance by adjusting salt and acidity.



-Coffee brewed with dairy in bag, allowed to bloom before sealing, then chilled in bag before straining. 96°C, 30 second bloom, 3 minutes sealed brew: Full range, 3-dimensional, well balanced. Very slight remaining metalic / bitter notes. Easily brought into balance by adjusting salt and acidity.


Note for making commercial quantities: 
consider preparing the coffee infusion separately, up to a day in advance. Store refrigerated in sealed bags after straining.


For further Reading:








Part 1 of this series: Introduction
Part 2 of this series: Components
Part 3 of this series: How to Build a Recipe
Part 4 of this series: Basic Recipe Examples
Part 5 of this series: Techniques
Part 6 of this series: Sugars
Part 7 of this series: Stabilizers
Part 8 of this series: Emulsifiers
Part 9 of this series: Booze
Part 10 of this series: Solids, Water, Ice
Part 11 of this series: Introduction to Flavor
Part 12 of this series: Ice Cream Flavor: Coffee
Part 13 of this series: Coffee Ice Cream Addendum: Origin Notes and Minutiae
Part 14 of this series: Chocolate Ice Cream