Monday, February 26, 2018

Introduction to Flavor


Earlier in this blog series I suggested that good texture was easier for industrial ice cream manufacturers, but that good flavor was easier for the home or pastry cook. This is because some of the tools that promote the finest texture—high-pressure homogenizers, high-end ice cream and gelato machines that can freeze the mix in mere minutes, blast freezers / hardening cabinets—are out of reach for many small shops. 

Meanwhile, good flavor depends, in part, on generous amounts of good flavor ingredients, which are almost always expensive. Premium vanilla beans (around $400 a pound in 2018) are a minor splurge for a pastry chef in a michelin-starred restaurant, or a home cook who doesn’t need to turn a profit. Might as well use the good stuff, and throw in an extra bean if it suits your whims. But for a manufacturer making ice cream by the boxcar, such price premiums are a killer—especially in the context of retail markups and price fluctuations, either seasonal or unpredictable (caused by draught, blight, politics, war, etc.).

But Not Easy

While it's not so challenging to get better flavor than Haagen Dazs or Ben & Jerry, that's not a particularly high standard. Good flavor is easy. Great flavor is hard.

This blog has been silent for many months, in part, because I’ve been researching and experimenting with flavor, and discovering along the way that every answer spawns several new questions. Surprisingly, there’s very little high-quality published science on getting the best flavors into ice cream. The breadth of the topic doesn’t help. A spice like vanilla behaves very differently from an herb like thyme, which behaves differently still from an herb like peppermint. None of these are at all like coffee, and none create the problems you’ll find with ingredients that add water, like fruits, or ones that add fat, like chocolate or nuts. Every flavor is a new adventure, demanding different science, presenting different complications.

When I worked at an ice cream shop way back in the 20th century, our approach to flavors was mostly formulaic. We'd usually use the most concentrated flavor ingredient possible, in the form of commercial extracts, dry spice powders, and cocoa powder. With problem ingredients (fruit, or our house-made, water-based coffee extract) we’d compensate for the extra water by throwing in extra cream. Mix it together, spin it, call it done. This is how most ice cream shops do it. The approach makes decent commercial ice cream, and it lets you use the same base for all your flavors, and gives you a process you can teach someone in a couple of days. But it’s not the path to the best ice cream, and it’s not what we're going to be discussing in the next few posts. 


There are a few basic ways to get flavors into ice cream. I've divided them into the following categories:

Simple recipes (Blend the flavor ingredient into the base)
-Extracts or essences
-Low-bulk spices (cardamom, star anise, peppercorn

Modified recipes (Blend in the flavor ingredient. Compensate by adjusting total fats, sugars, milk solids, etc.)
-alternative sweeteners (honey, molasses, etc.)

Infusions Brew flavor into liquid ingredients at specific temperature and time, strain out)
-high-bulk spices (vanilla)
-aromatic vegetables (ginger)

Recipies with additional processes
-caramelizing sugar
-reducing wine or spirits
-toasting nuts
-browning butter

Compound recipes (Combining two or more of the above)
-dark sugars ice cream (caramelizing sugar, modifying base recipe)
-brown butter cognac ice cream (browning milk solids, reducing spirits, modifying base recipe)
-bourbon smash ice cream (infusion, modifying base recipe)
-coffee (infusion, modifying base recipe)

What is Flavor?

Flavor describes a complex set of physiological-psychological perceptions, based on taste sensations from the tongue, olafactory sensations from the nose, and a whole range of expectations and biases created by what we see, hear, believe, and remember. The science of flavor is young and rapidly expanding. The lore goes back about as far as recorded history.

In this series we're mostly going to be talking about the tongue and nose. The psychological / perceptual sciences are a bit above my pay grade (I happen to get paid nothing for this ... thank you for asking). 

You may have been tought that the tongue perceives just four tastes: sweet, salty, sour, bitter. This is pretty close, but we now believe that in addtion to these four, there is also at least one type of savoriness (umami), which describes our response to glutamic or aspartic acids in meat, seaweed, and aged cheeses; there is a taste for alkalinity (think of soap); there are possibly many distinct types of bitterness; and there may be other distinct tastes associated with fat, metals, and calcium.

There are also sensations that are similar to tastes but that are actually physical sensations unrelated to the tongue's taste receptors: pungency (the chemical burn from hot chilis); astringency (the grainy and puckery sensation from tannins in red wine, black tea, and rhubarb); coolness (triggered by mints, ethanol, camphor, and some sugar alcohols); numbness (triggered by some Sichuan chilis and by cloves). 

This describes around a dozen sensations in the mouth. The nose, however, knows no such humble limits. We can detect thousands—possibly tens of thousands—distinct aromatic compounds. And we're discovering new ones all the time. Here's a simplified chart breaking down organic aromatic compounds by family and molecule size. This includes a range of them from herbs to jet fuel, but is far, far from exhaustive:

Table of Aromatic Compounds

Some of this is academic; some may be useful when we have to solve problems. For example, you may find that an herb contains aromatic compounds that you like and ones that you don't. If they are soluble at different temperatures, this will help you decide the temperature of your infusion. Some compounds may be much more soluble in fat than in water. If you want those compounds, then infuse into the cream. If you don't, then infuse into the milk. And so on.

But let's start with something simple. Here's a recipe from the first group, aptly titled Simple Recipes, because you don't have to make any adjustments to the base recipe, and you don't have to use any specieal technique (besides turning the blender on):

Simple Recipe Example: Green Tea Ice Cream  

-12g matcha powder 

-Combine matcha with the other dry ingredients and make as usual. Easy peasy.


Matcha is powder ground from whole green tea leaves. In Japan it's whisked into hot water and enjoyed as a full-bodied tea. Since the powder is expensive, matcha is considered a more special drink than ordinary brewed green tea. Matcha comes in several grades, from "ceremonial" to "premium" to "café" to "culinary" to "classic." The highest grades are distinguished by their delicacy and subtlety, and so are almost always consumed straight without any milk or sweetener. The delicacy does not hold up to the dairy and sugar in ice cream, so it makes the most sense to use a good quality, fresh, culinary grade in this or other green tea ice creams.

For a very intense matcha flavor, increase the quantity to 18g powder. If using 18g and you find you need to decrease bitterness, add  0.4g citric acid and 1.3g additional salt (increase salt in recipe to 2g total)

This is a standard flavor balancing tactic, not just in ice cream but in all cooking, sweet and savory. Some universal guidelines:

-To counteract bitterness, increase salt or acid
-To counteract acid, increase fat or bitterness
-To counteract sweetness, increase acid or bitterness
-Salt will bring forward mid-range, warm, savory flavors
-Metalic flavors are often the product of imbalanced acids

Next post: Coffee Ice Cream (aka Simple Cooking Made Complicated)

For further reading:

How Does Our Sense of Taste Work? [Informed Health Online, via PubMed]

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


  1. Hi

    Your blog has helped me create fantastic homemade ice cream and I'm so glad that you're still updating it!

    Just wondering though, what role does the citric acid play in combating the bitterness of the matcha? Likewise for the salt - could it be used to reduce the bitterness of other intense flavors like dark chocolate?

    1. Thanks for writing, Basmoth. I updated the matcha ice cream recipe with notes on the salt and acid. Short answer: yes, salt and acid always counterbalance bitterness. This is a useful principle with any kind of recipe,

    2. Awesome, thanks for the reply! You've just given me a new ingredient to experiment around with.

      Anyway, do you think a concentration of ~0.04% citric acid work similarly well for an intense coffee or dark chocolate flavor?

  2. I've never had a problem with bitterness in a chocolate ice cream, so it's hard to say (and I use about as much dark chocolate as you can get away with before people will mistake it for pudding).

    For coffee, check out the coffee ice cream recipe I just posted.

  3. Wow! New posts about flavor.

    A simple chocolate ice cream would be great, although with the previous posts I had very good results I am very interested in seeing your methods.

    Keep up the good work and a huge thanks.

  4. Hi Paul Raphael !
    I´ve one question because of the flavour when making nut-ice cream:
    When is the best time to add the nut-paste into the base or ice cream to get the best flavour outcame ?
    (when cocking the base; or in the cooled base before ripening; or just before creaming; or into the ice machine some minutes before taking out the ice cream - when the base is already soft frozen ?)

    Thank you for your great blog about ice cream !


    1. Hi Christian,
      I haven't tested this specifically, but I always add the paste / nut butter before cooking the mix. I want to give the emulsifying ingredients a chance to interact with the nut oils. This may give a smoother texture. The nuts I've worked with have all been toasted at high temperature already, so I'm not concerned about harming the flavor with a little bit of heat. Possibly if you were working with something like a raw, homemade pistachio butter you'd notice a flavor difference pre- and post-cooking, but I'm not even sure about that.