Sugars in Ice Cream

 
 
 
[This article was substantially revised in April 2019 and June 2019. Thanks to experience and advances in our software analytics, we’ve updated our approaches to sugars since this first went live in 2016.]

 

Sugars: they’re sweet, and they keep the ice cream soft. If you’ve had homemade ice cream with the consistency of concrete, it’s because the level of solids—especially sugars—was too low. 

Some bloggers and cookbook authors tell you to soften the ice cream by adding alcohol. This works, but you can do better. While alcohol depresses the freezing point, it does so at the expense of smoothness. By increasing the unfrozen portion of water in the ice cream, while doing nothing to help control that water, it will encourage ice crystals to grow larger. You’ll end up with a softer but grainier texture. 

 
 
Personal narrative and manifesto:
 
The quick fix would be to add more sugar, but most ice creams are too sweet already. A typical home recipe is 17% or more table sugar by weight: candy. You can’t taste any subtlety through cloying sweetness—you can’t taste the dairy, and you can’t taste any of the more delicate, aromatic flavors we’re going to work so hard to put in there. 
 
It’s not just home recipes. Haagen Dazs is too sweet. Ben and Jerry’s is too sweet. Talenti is too sweet. Cold Stone is too sweet. Every small town “homemade” ice cream shop I’ve ever wandered into: too fricking sweet. 
 
I once managed an ice cream shop in Colorado, making ice cream that the owners and I were proud of. It was way too sweet, of course, but I had no reasonable frame of reference, until after I’d quit and taken a trip to Paris, where I was lucky enough to be invited to dinner at Taillevent—a restaurant which at the time had three Michelin stars and which had once been considered the finest in the city. After uncountable savory courses, we were put in the hands of pastry chef Gilles Bajolle, who would soon become the first chef that I’d shamelessly steal or reverse-engineer recipes from. He was most famous for his marquise au chocolat with pistachio crème anglaise (which indeed I stole and worked on for many years) but the dish that opened up the heavens for me was the single unadorned quenelle of thyme ice cream.
 
There’s nothing surprising today about an herb flavored ice cream. But back in the 20th Century, for someone who’d been making flavors like “rocky mountain road,” an herb flavor besides mint was a sucker-punch to the imagination. And the flavor itself: let’s just say that I took a bite and sat there, very quietly, rethinking everything. The sensations kept developing, unfolding, surprising, telling stories. It was obvious that this was the first truly good ice cream I’d ever had. 
 
Only later did I realize that one of its secrets would be easy to duplicate, at least in theory: make the ice cream less sweet. Let the herbs and the dairy do what they do.
 
End Rant.
 
 

The Problem

 
Conventional ice cream is too sweet, but reducing the sugar content makes it too hard at serving temperatures.
 

The Solution

 
Use different sugars.
 
Michael Laiskonis, former executive pastry chef at Le Bernardin and current Creative Director at the Institute of Culinary Education, taught me how to think about using sugars. 
 
Freezing point depression is dependent on the molecular weight of a dissolved ingredient. The lower the molecular weight, the smaller the molecule, and so the more molecules per gram—and the greater the reduction of the freezing point.  Please see the article on solids, water, and ice.
 
Consider the following table [updated 8-29-2020]:
 
 
Sugars property chart
We want to look at three factors independently: Sweetness, Freezing Point Depression, and Solids 
 
The chart, in keeping with industry conventions, shows all values in relation to sucrose. Sweetness is expressed either as Relative Sweetness, Sucrose Equivalence, or POD (“Potere Dolcificante”). For our purposes we can use these terms interchangeably. The important point is that sucrose has a value of 100. A higher value is proportionally sweeter; a lower value is proportionally less sweet.
 
Freezing point depression is expressed either as FPDF (freezing point depression factor) or PAC (“Potere Anticongelante”). These terms can likewise be used interchangeably—but when given the chance, why not use an Italian acronym? Sucrose again has a value of 100. 
 
Solids are just solids, expressed in percent. Everything in the mix besides water, air, and alcohol. We prefer high-solids sugars (solids >90%) because we want to avoid adding water whenever possible. Liquid sugars (glucose syrups, corn syrups, invert syrups) also tend to be less consistent products. The proportion of water can vary from sample to sample. 
 
I find it useful to not just look at the individual POD, PAC, and solids values, but to consider the ratios. This tells us how to use different proportions of sugars to solve problems. 
 
The most important ratio is PAC : POD. This helps us control freezing point depression independently of sweetness. With a value of 1, sucrose has the lowest ratio among the most useful sugars. If you prefer your ice creams less sweet, higher-ratio sugars like fructose and dextrose will allow you to control sweetness while still hitting your targets for freezing point depression. For example, with a value of 2.5, Dextrose has the highest ratio among our most-used sugars  (Lactose and Atomized glucose are higher still but their usefulness is limited. See below).
 
The other important ratio is Solids : POD. This helps us control sweetness and total solids independently. Among the most useful sugars, dextrose has the highest ratio; fructose the lowest. If your formula needs more solids as well as more sweetness, increasing the proportion of dextrose or sucrose will help. If it needs more sweetness, but is already pushing the limits of solids, increasing the proportion of fructose will help. Atomized glucose, maltodextrin, and lactose have very high ratios, but their usefulness is limited (see below).  
 
The sugars we care most about are sucrose, dextrose, and fructose. 
 
Sucrose is table sugar. Since it’s the most familiar, and has the flavor we most expect, we use it as our foundation. It also provides a frame of reference for understanding the other sugars. Sucrose is a disaccharide, meaning that it’s a molecule made up of two smaller sugar molecules—in this case the monosaccharides glucose (dextrose) and fructose. 


Dextrose (another name for the monosaccharide d-glucose) is about 3/4 as sweet as sucrose, but has nearly double the effect on freezing point suppression. Simply by decreasing sucrose and increasing dextrose, you can lower the sweetness while simultaneously softening the texture. Magic! Dextrose is also hygroscopic, meaning that it holds onto water, reducing the formation of both ice crystals and sugar crystals. It’s effectively a stabilizer, although it’s much less powerful than dedicated stabilizers.

Fructose is a monosaccharide, which, along with glucose (dextrose) makes up both table sugar and invert syrup. It has the same high freezing point suppression of dextrose, but is much sweeter—about 25% sweeter than table sugar, 80% sweeter than dextrose. We use fructose to increase both sweetness and freezing point depression while minimally increasing solids. Like dextrose, fructose is hygroscopic, helping to control water and reduce crystallization.
 
Invert syrup is a liquid sugar. It’s made by heating sucrose syrup with a weak acid until it the glucose and fructose molecules detach from each other. It’s sweeter than sucrose, and offers stronger freezing point suppression. It’s in the pantry of every pastry chef, thanks to its powerful hygroscopic qualities. As with dextrose and fructose powders, foods made with invert syrup stay moist longer and are resistant to crystallization. Invert syrup is not as good a choice as powdered fructose, because it adds water, it’s harder to handle, and its precise composition (water content, residual sucrose content) are variable. But we include it because it’s a pantry staple for every pastry chef; fructose is not. 
 

Dextrose, fructose, and  invert syrup can be especially helpful with flavors that require adding non-dairy fats, like cocoa butter (chocolate) and nut oils (nut butters). These fats tend to freeze harder milk fat, and give ice cream a dry, stiff, crumbly texture. Increasing the proportion of these monosaccharides can help preserve a smooth texture.

Other Important Structural Sugars

Atomized Glucose is useful in odd cases when you need maximum solids, high freezing point depression and minimum sweetness. It contains dextrose, and a whole stew of other mono-, di-, and polysaccharides, including dextrins. This gives it bulk without much sweetness. The trouble with atomized glucose is that it’s not a consistently defined product; you don’t know for sure what you’re getting or what its properties will be. Atomized glucose is a pantry staple for some pastry chefs, especially in Europe. It leads to some confusion, since some chefs don’t know the difference between it and dextrose, and some recipes don’t specify which to use.  

Maltodexrin adds solids and bulk with minimal effect on sweetness or freezing point. It’s a bit of an anti-sugar in this sense. It’s useful in particular sorbet flavors which by their nature are low on solids, and so need something to combat their innate wateriness—ones like lemon and watermelon. These flavors are built from fruit juices that are mostly water. Maltodextrin is a bit like atomized glucose minus the glucose. We’ll address sorbets generally in another post.

In ice cream, skim milk powder works better than maltodextrin. And the latter does all the bad things to your body that sugar does, without the benefit of tasting like anything. But milk solids are generally not an option in sorbets, which everyone expects to be dairy-free.

Inulin is technically a starch (derived from plants like chicory and Jerusalem artichokes), but we’re including it here because it offers some sugar-like behavior (some sweetness, some freezing point depression). It’s mostly used as a non-caloric fat replacer, since it has textural qualities similar to fats (this use is outside our purview; if you’re on some kind of diet, you’ve walked into the wrong room). It is, however, pure magic in sorbets, used at around 3.5% the water weight of the formula. It’s slightly exothermic, so it produces a mild warming effect when it melts in your mouth. This can counter the (usually undesirable) cooling effect of ingredients like erythritol. Inulin is interesting to us for cases where we need high solids without a lot of sweetness or freezing point depression. Nominally it doesn’t look as good as maltodextrin for this purpose, but inulin’s textural properties allow it to behave like a much larger dose of solids. You can think of it almost as a specialty stabilizer that also adds POD and PAC. As a bonus, it doesn’t have the lousy health impact of maltodextrin, and is non-dairy—which makes it an ideal choice for adding bulk and creaminess to sorbets. 

Trehalose is a naturally occurring disaccharide composed of two glucose molecules stuck together. It’s much less sweet than sucrose, but has the same freezing point depression factor. Its properties are very close to those of lactose. But since the source of lactose is milk solids, it’s not useful in sorbets. Sorbets are the ideal application for trehalose, where it’s often a battle for getting the solids and freezing point correct without creating a cloying sugar-bomb. Trehalose does have a some disadvantages compared with lactose. It’s much less soluble, so we usually limit quantities to a few percent. Relatedly, it does not offer the incredible water control of lactose. It’s also an uncommon ingredient, in many cases leading us to special orders and jacked-up prices, so it’s good that we don’t need piles of it.

Erythritol is a naturally occurring sugar alcohol that provides sweetness with virtually no caloric value. We mammals don’t have the enzymes needed to break it down. Many sugar alcohols are, however, highly digestible to our gut bacteria, which can lead to gas and bloating. Erythritol is much less problematic in this regard. It’s primary drawback is its high price. It’s also endothermic, meaning that it that pulls in heat as it dissolves, creating a cooling effect in the mouth. This is refreshing in breath mints, but not so pleasing in an already-cold dessert. This can be combated with an exothermic ingredient (like inulin) or by just limiting the amount you use. The key benefit of erythritol is its very high PAC:POD ratio, making useful for controlling freezing point and sweetness in sorbets. 

Lactose is the sugar that’s already in your milk and cream. Skim milk powder is about 50% lactose by weight—so you might as well just get your lactose from the SMP, which belongs in every recipe anyway. Lactose has the same freezing point depression factor as sucrose, but with sweetness that’s so low it’s barely detectable: highly useful for increasing solids and  freezing point depression independently of sweetness. Lactose is also a champion in terms of water control. Lactose can absorb roughly six times its weight in water, which gives some stabilization power, and makes it more effective than most other sources of solids. 

In Practice

 
I want my ice creams to have a POD (relative sweetness) of 110–120 (equal to this many grams of sucrose per 1000g).
And I want them to have a PAC (freezing point depression factor of 220–230 (also equal to this many grams of sucrose per 1000g).
 
In a formula that doesn’t include flavor ingredients that contribute sugars, water, or anything else that messes with texture, I can achieve these values with a standard blend.
 
Standard Sugar Blend
 
(per 1000g)
80g sucrose
45g dextrose
 
Here’s the math:
 
                                      POD       PAC
80g sucrose                   80          80
40g dextrose                  29          76
70g skim milk powder    6            38
Other ingredients            0           26
Total                              115        219
 
This is right on target, in the middle of my ideal range.
[These guidelines differ somewhat from the formulas you’ll see elswhere in the blog series. We will eventually update those formulas to reflect this more refined approach]
 
 

How to Tweak:

 
Is the sweetness ok but the consistency too hard? Less sucrose, more dextrose. Maintain POD and increase PAC.
 
Is the sweetness ok but the consistency too soft? Less dextrose, more sucrose. Maintain POD and decrease PAC

Is the consistency ok but the sweetness too high? Less sucrose, more dextrose. Maintain PAC and decrease POD
 
Is the consistency ok but the sweetness too low? Less dextrose, more sucrose. Maintain PAC and increase POD
 
Are the sweetness and consistency ok but the solids too low (lacking density and creaminess)? Increase milk solids and slightly decrease dextrose. Maintain PAC/POD, increases solids.  
 
Are the sweetness and consistency ok but the solids too high (too dense / chewy / gummy)? decrease milk solids and slightly increase dextrose.

Maintain PAC/POD, decrease solids.  
 
Are there ingredients that add fats which could harden the ice cream—like chocolates or nut butters? Decrease cream, increase milk. Decrease sucrose, increase dextrose and fructose. 

Are you adding flavor ingredients that have their own sugars? Like fruit, chocolate, gianduja, or liqueur? Calculate (or estimate) the amount of added sugar and reduce the sucrose by the same amount. 

With fruit, look up the actual composition of the fruit (it usually contains sucrose, fructose, glucose, and other sugars). You can compensate by reducing the glucose as well. We’ll discuss this in detail in a future post on fruit flavors. Or, as a shortcut, use calculated POD and PAC values for each fruit, and adjust the sugars to compensate. 
 
Finally, are there flavoring ingredients that will directly effect the freezing point—namely alcohol? If there’s a lot, the ice cream may need all the help it can get to harden enough. Eliminate the glucose. Reduce the sucrose, too, if there’s any room to lower the sweetness. Add a bit of nonfat dry milk to get th solids up, and increase the stabilizers. We’ll discuss this in detail in a future post on booze flavors.

 
 
 
      
 
 

More Sugars


Honey is a useful sugar in some ice cream flavors. It behaves mostly like invert syrup (because it IS mostly invert syrup—around 75% by weight), and tastes rather strongly  … of honey. Because it adds about 20% water to the recipe, and increases body, it’s generally not a good idea to substitute honey for all the sucrose. But up to 50% works fine. It can be interesting to experiment with some of the more exotic and intense honey varieties, like buckwheat, heather, and chestnut. You’ll probably want to use these honeys in moderation. Mild honeys like clover and alfalfa are most traditional.

There are other varieties of glucose, including atomized glucose powder, corn syrups (typically around 1/3 glucose by weight) and various glucose syrups, identified by their DE number for dextrose equivalence. The DE number technically refers to the percentage of reducing sugars—in this case meaning either glucose or fructose. The higher the DE number of a glucose syrup, the more glucose it likely contains, and the greater the freezing point suppression. Atomized glucose is just spray-dried glucose syrup. It contains more water than anhydrous dextrose. Here’s all you need to know: Don’t use any of this stuff unless it’s all you can get your hands on. Pure Dextrose powder and invert syrup are more useful, and make it a lot easier to know what you’re getting.

Caramel is useful as a flavor ingredient. A little goes a long way, which is convenient—because it’s hard to know how caramel will effect the ice cream’s texture and freezing point. Caramelizing sugar is a gradual process by which some portion of the sucrose molecules break down into smaller molecules, and combine into larger, more complex, more flavorful ones. I like to use a small quantity of caramel, but to cook it to a fairly dark and flavorful degree. This way it will behave less like sugar in the recipe, and will have maximum effect on flavor.

You might also experiment with using caramels browned to different degrees—like a medium caramel, for more traditional toasted flavors, and a dark caramel, for the more complex and bitter burnt sugar flavors.

Caramel is challenging to calculate for. Its sweetness diminishes gradually as cooks darker, and at a certain point gets overtaken by bitterness. Its freezing point depression factor increases in the early stages of cooking, as the sucrose breaks down into monosaccharides. But as cooking progresses, larger molecules form, reducing the freezing point depression. Light-to-medium caramels can probably be treated like invert syrup. 

Molasses is unrefined syrup centrifuged off from sugar cane syrup after it crystalizes. It contains all kinds of stuff, including water, so it’s best to use in small quantities just for flavor. The primary sugar component is sucrose.

Maple syrup is also useful as a flavoring. Like molasses, its primary sugar is sucrose (typically 52%), and it contains water (typically 45%) plus around 3% invert syrup.. It’s not easy to know precisely how much water is in there, since syrup is boiled down to whatever level the maker desires. Fortunately, a little goes a long way. Grade B is the most flavorful. The grade signifies darkness and not quality; annoyingly, many grocers don’t know their trade and stock only the inferior Grade A. It’s worth it to find a reliable local source of the good stuff. Maple syrup is so expensive these days, you should get all the flavor you can from every ounce.

Non-Caloric Sweeteners

It’s not easy, but it’s possible, to make decent sugar-free ice creams. The trick is finding ingredients that taste like sugar, adequately suppress the freezing point, and won’t give you a bellyache. 
 
By these standards, the perfect ingredients do not exist—although some of the sugar alcohols, like erythriol, come pretty close. We’ll discuss these in a later post (although I’m no expert on the topic).
 

In the next post we’ll explore the dark arts of stabilizers.

 

 

Appendix 1: Invert Syrup

How to make Invert Syrup

 

250g sucrose
120g water (approx)
0.25 – 0.5g citric acid or cream of tartar (tartaric acid)
 
 
Mix ingredients in a saucepan and bring to a boil.
 
Once the mixture boils wash away any sugar crystals stuck to the side of the pan with pastry brush dipped in water. Water from the brush won’t affect the outcome.
 
On medium heat without stirring boil the mixture to 235°F / 113°C. Remove from heat and cover the pan. Let cool at room temperature until it’s reasonably safe to handle. transfer to plastic container. Store in a refrigerator. Invert sugar will last at least a few months. 
 
You can melt and re-cook it if starts to crystalize. Toss it if you see mold.
 

Most professional kitchens just buy the stuff.

 

So—What is Invert Syrup?

Sucrose is a disaccharide, meaning a sugar molecule made up of two smaller monosaccharides: glucose and fructose. When we make invert syrup, we split these two monosaccharides apart, with the addition of water—a reaction called hydrolysis. Hydrolysis can occur with just the addition of water and heat, but an acid catalyst improves the efficiency of the reaction.

Typically, we can split (invert) about 85% of the sucrose. Manufacturers may be able to invert more of the sugar, by using other chemical or enzymatic catalysts.

When you cook your own, you control the final water content with the cooking temperature. Cooked to 113°C–114°C the final syrup will contain a bit under 20% water. This is dry enough to work in ice cream without adding too much water, and gives a long life in the fridge. But it’s not unreasonably gluey. 

 
The stuff is great to have around. In addition to magic it works on ice cream, substituting about 10% invert syrup for sucrose in most desserts will improve moistness and add shelf life.
 
 
Why is it “Inverted?” 
 
This may be the most useless piece of knowledge in the entire blog series. But you asked. 
 
Chemists measure the composition of optically-active solutions with a polarimeter, which passes plane-polarized light through the solution being measured. When the solution contains sucrose, the light rotates to the right. When the solution breaks down to glucose and fructose, the light rotates the other way, hence the inversion: 
 
C12H22O11 (sucrose, Specific rotation = +66.5°) + H2O (water, no rotation) → C6H12O6 (glucose, Specific rotation = +52.7°) + C6H12O6 (fructose, Specific rotation = −92°) net: +66.5° converts to −19.65° (half of the sum of the specific rotation of fructose and glucose). 
 

This inversion of polarized light has no known application in the kitchen. Not even Nathan Myhrvold has suggested that we run out and buy a polarimeter. Just try to remember that inverting sugar does not mean turning the bag upside-down. 

 
 

Appendix 2: Sample Recipe

 

Quartet of Dark Sugars Ice Cream

I wanted to create a recipe that gets all its flavor from the sweeteners, and that explores the possible depth and range of those ingredients. It uses caramel, molasses (from the dark muscovado sugar), maple syrup, and chestnut honey. It’s about layers of flavor. Background hints of vanilla and salt take it an extra step. It’s not kid stuff—it isn’t even especially sweet.
 
Muscovado sugar is a semi-refined brown sugar that’s heavy on molasses and has a deep, complex flavor. Chestnut honey is dark, bitter, and challenging. For the maple syrup, look for one marked “Grade B”, which is darker and more flavorful than grade A. The grade has nothing to do with quality.

I’ve written this for cooking in an immersion circulator, but it adapts fine to the stovetop or other heating methods.
 
Makes 1 to 1.3 liters
 
55g dark muscovado sugar
50g nonfat dry milk
 
3g salt 
0.8g locust bean gum (TIC or Willpowder)
0.4g guar gum
0.2g lambda carrageenan
 
35g (approx) water
35g granulated sugar
30g (approx) water
 
460g  whole milk
2 egg yolks (36g)
27g chestnut honey 

25g maple syrup

270g  heavy cream

10g (2 tsp) alcohol-based vanilla extract

 
-thoroughly stir together muscovado sugar, dry milk, gums, and salt.
-set immersion circulator to 75°C
 
-heat 1st portion of water and granulated sugar in a saucepan. Cook to medium-dark caramel.
-turn heat low. Deglaze with second portion of water. Water will boil off and caramel will clump.
-when water is mostly gone, add milk and stir to disolve caramel. Stir in the honey and maple syrup.
 
-pour milk mixture into blender.
-set blender speed to create a vortex; add powdered ingredients. cover and blend on high for 30 seconds to disperse the stabilizers.

-add yolks, cream and vanilla extract.

-briefly blend again on high speed.
 
-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 set custard, hydrate stabilizers, denature milk proteins.
-gently agitate bag after 5 and 15 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 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 4 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.
 
-harden in a blast freezer for several hours, or overnight in a cold standard 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.
 
Analysis:
Total Fat: 12.1%
Milk Fat: 11.3%
Total Solids: 37.4% (a little lower than ideal)
Solids Nonfat: 25.3%
Milk Solids Nonfat: 10.6%
Acidity: 0.17%
Alcohol: 0.3%
Stabilizer/Emulsifier: 0.14%
Egg Lecithin: 0.29%
POD: 114 / 1000g
PAC: 263 / 1000g (a little higher than ideal)
 
 

Appendix 3: FPDF, PAC, Absolute PAC

Problems in Quantification 

 

There are some confusing conventions in the ice cream world, concerning how these values are calculated for an entire formula. In the US, it’s common to quantify a formula’s freezing point depression factor withf FPDF, or freezing point depression factor. This is calculated only with the sweeteners, but ignores the significant effects of milk solids (which are about 50% lactose, plus salts). In most of Europe, they use the PAC value, which by convention takes the milk solids into account, along with the various sugars and salts (and possibly alcohol) in the flavor ingredients. PAC is an improvement.
 
Even PAC is imperfect, however, because it doesn’t account for the total amount of water. The values are based on a given quantity of total ingredients, which, depending on total solids, may have a little or a lot of water that needs to be controlled. PAC divided by total water gives a value I call “Absolute PAC” which corresponds more closely to the actual observed freezing point depression. Calculate water by subtracting total solids, and any alcohol, from the formula weight.
 
Just don’t expect anyone to know what you’re talking about when you use this term; it’s not an industry convention.
 
Absolute PAC, plus some fairly daunting math, can be used to estimate the final ice fraction of the ice cream at any given temperature. And ice fraction, along with the concentration of saturated fats (cocoa butter, nut butters, etc.) and the final overrun (volume increase from air) can be used to model the ice cream’s final hardness. You need a lot of data and many equations to create even a rough estimation. We’re constantly refining our own software tools to do a better job at this; unfortunately, any kind of useful hardness modeling is too arcane to dive into in a blog article.
 
 

Shameless Plug:

 
Keep an eye out for my photography book on the Brooklyn Domino Sugar Refinery.
 
Cover of Brooklyn's Sweet Ruin: Relics and Stories of the Domino Sugar Refinery
 
 
 
 

38 Comments


  1. Thanks for looking further into this.

    Anecdotally, glucose has been working well in my home experiments.Reply

    • I’m curious to know the answer to this as well. I can’t imagine how invert sugar wold impart any benefit aside from the freezing point depression of the inverted sugar components. Maybe the viscosity plays a role? Though I would think this would be lost when it’s heated and dissolved with the mix.Reply

  2. Hi Paul,

    Sorry to take so long with a response. Your question has occurred to me before, and I've never been able to find an answer. There's no shortage of sources that go on endlessly about the benefits of invert syrup. None that I've found say why (or if) it's any different from a glucose and sucrose dissolved together.

    I'm waiting for answers from a couple of real chemists and will let you know what i find out.Reply

  3. First of all, thank you for sharing your knowledge on ice cream! Your articles are a pleasure to read and have taught me a lot.

    I have a quick question regarding invert sugar:
    Are the stabilizing & textural benefits of invert syrup attributable to its monosaccharide constituents, or is there some other underlying cause?

    Would I get the same effect by using a proportional amount of anhydrous glucose / fructose in place of invert syrup?Reply

  4. I think Lebowitz is just trying to keep things simple for people. Alcohol works. But unlike sugars, it doesn't do anything to improve the ice cream's texture. By lower the freezing point without adding anything to improve body or stability, alcohol actually results in an icier ice cream, not a smoother one.

    In a later post I'll get into alcohol flavors—for these we add more nonfat milk solids, and change the sugar blend so we don't get too much softening.Reply

  5. David Lebowitz says use alcohol to soften ice cream. What's wrong with this?Reply

  7. Hi Jerome, thanks for writing.

    Dextrose and glucose are interchangeable names for the same sugar. The only likely difference in practice is that products labelled Dextrose are (usually) the anhydrous or monohydrated powdered forms of the sugar. These versions contain little or no water.

    Sugar labelled Glucose, when sold in baking supply stores, is often either a syrup or "atomised glucose"—which is a powder made by spray-drying glucose syrup. Both of these products contain a lot more water than the Dextrose powder products.

    It's also possible that some products sold as Glucose are identical to Dextrose powder, but it can be hard to tell.

    The bakery glucose products typically add more water than we want to add to an ice cream formula, but the worse problem is that we often don't know how much.

    So it makes life much simpler to just use Destrose powder.

    As far as overrun, there's no difference between any of these, at least if you compensate for any added water. The sugar molecules are identical.Reply

  8. Thank you for sharing all these informations. However I'm wondering about the use of glucose, which is almost always used by professionnals, here in France.
    In contrary, dextrose is not recommended by french ice cream makers because it might significantly limit overrun. What do you think about this ?
    Reply

  10. "Quartet" recipe came out GREAT! My wife said it would probably pair with a nice stout!

    Boy, to think of all the failed batches I could have prevented eating if only I found this site first. So...many...calories...

    Not only is this the best technique around it is all explained in ways that make sense. Excellent job, I just wish you were able to post more often! (but grateful to get it when you're able)

    THANKS!!!Reply

  11. I asked chef Laiskonis your question. He doesn't see why it wouldn't work, and suggests trying it. The substitution isn't interesting to him, because as a pastry chef, he always has invert syrup on hand, but doesn't use fructose powder.

    I find the idea compelling, though—because it's easier to work with powdered ingredients than with a heavy syrup in ice cream. I haven't tried it yet, because to to set up a controlled experiment is difficult, and I don't have facilities for making identical, simultaneous batches of ice cream.

    I'm looking for a food scientist to ask.Reply

  12. I've substituted fructose for invert syrup in several batches of ice cream now, and it works fine. I don't have the means to do side-by-side blind tastings, so don't take my word as gospel. But based on casual experience, and my understanding of the science, it doesn't make a difference—except that fructose allows you to add a bit less water to the recipe. Which would be a positive difference, if noticeable at all.

    I find fructose easier to work with, and so will switch to it for my own use. But I'll keep posting recipes with invert syrup, since this is standard pastry kitchen ingredient.

    The substitute blend I'm using in my standard ice cream base:
    70g granulated sugar
    30g dextrose
    5g fructose
    Reply

  13. Hi Jonas,
    to keep things simple I don't account for the water weight of the invert syrup. The stuff is usually around 20% water, we're talking about a few grams of water at most.

    So with invert, honey, glucose syrup, I'm talking about the whole weight of the thing.

    If you want your spreadsheet to be extremely precise, you could have it parse those values internally—so it would assume, for example, that 15g invert syrup means 6g glucose, 6g fructose, and 3g water). When I'm working things out by hand, this degree of precision gets unruly, but if a spreadsheet is doing the heavy lifting, why not?

    It makes perfect sense that your alcohol experiment yielded an icy texture. Alcohol doesn't help control the unfrozen water, so you get softness at the expense of iciness. If you want to get really nitpicky, alcohol's will have a sweetness level that's somewhat higher than zero ... although my guess is that you can ignore this. At the alcohol and sugar levels likely to be present in ice cream it's probably imperceptible.

    Good luck with the spreadsheet. I'd love to see it.Reply

  14. Two Quick Questions:

    "My starting point is 13% sugar by weight (not counting the lactose in the milk).

    The blend consists of:
    60% sucrose
    26% dextrose
    13% invert syrup"

    Is the 13% inverted Syrup defined as "the weight of the contributing sugars (not including water)" or "the total weight of the inverted syrup (including water)"?

    In addition, in your table, defining freezing points and sweetness factors, does this already account for the water content in inverted syrup or honey or is it just considering the sugar components of the ingredients?

    I'm working on a spreadsheet that you can create ice cream recipes on and have it automatically generate it's ingredient breakdown (i.e water percentage, milk fat percentage, etc.). With that spreadsheet, I am working to account for different sugars. At the end of the spreadsheet, I have a sugar sweetness rating (Based on sweetness of the total sugars per total volume) and The sugar equivalent of freezing potential (total percentage of sugar at relative freezing suppression of 1.00). I have also accounted for alchohol (0 sweetness, 7 freezing suppression) but found that the mixture was icy . I just want to make sure I understand the information in this section so I am calculating the correct sugar amountsReply

    • Hi Jonas, Another reply mostly for the benefit future readers. I've significantly updated the information on this page to reflect some new approaches. The ratios you're asking about have been replaced by new ones.Reply

    • Hi, is it possible to find thos excel file somewhere? Thank youReply

  15. Dave Arnold, former technology director at the International Culinary Center in NYC, has confirmed that powdered glucose and fructose should work the same as invert syrup.Reply

  16. Hi,
    Compliments for the very informative blog.
    My egg-less white mix recipe (about 6.5% fat) includes the following combination of sugars:
    6% 43 BE GLUCOSE, 5% SUCROSE and 8% INVERTED SUGAR.
    I’d love to substitute the annoying glue 43 BE glucose for a dry sugar equivalent.
    Would anhydrous glucose powder be the best option? If so, what would be, let’s say, the equivalent for 1 kg of the 43 BE glucose.
    Many thanks for your kind attention and sharing your knowledge.
    Reply

  17. Hi Anon,
    yes, I've been playing with the spreadsheet a bit. I don't know my way around it well enough yet for it to be primary tool, but it's nicely done and I can see it becoming a big time saver. I may have to learn some more about Excel ... there are some things I'd like to customize on it. Thanks again for sharing.Reply

  18. Did you ever get the spreadsheet working?Reply

  19. Hi,
    I have question about Trimoline AFP.
    What is correct AFP number in trimoline? I learn from Italian gelato chef he told me 190 AFP..
    Its there has different trimoline?
    Reply

  20. I'm not familiar with the AFP scale, so I'm not completely sure what the numbers mean. The scientific way to look at freezing point depression is simply to look at the molecular mass of the ingredient. The lower the mass, the greater the freezing point depression. And the relationship is linear.

    Take a look at the table above. Invert syrup is listed as having a molecular mass of 204, which gives it 1.67 times the freezing point depression of sucrose (67% greater).

    If AFP is based on sucrose, and if sucrose is 100, then it sounds like your gelato chef friend is giving you the numbers for either glucose or fructose; an understandable assumption, since invert syrup should just be a mix of these two. But because not all the sucrose gets inverted the math works out a bit differently.

    Also keep in mind that any numbers given for invert syrup are estimates, because the actual water content and the actual efficiency of the hydrolysis can vary. Commercially available invert syrups will probably contain a lower percentage of residual sucrose than homemade versions, so their freezing point depression (and sweetness) may be a bit greater.

    [Thanks to your question, I re-calculated the numbers for invert syrup in the chart. Previously I reported the total molecular mass, rather than giving a weighted average of the glucose, fructose, and residual sucrose. The new value is shown as the effective molecular mass.]Reply

  21. Hi Bruno,

    yes, anhydrous glucose would be an excellent ingredient. I'm pretty sure that culinary dextrose is glucose monohydrate, which is equally good, and possibly cheaper. I like both of these much better than any glucose syrup.

    I don't have data for 43DE glucose, but assuming it's similar to 42DE, it has about 60% the sweetness of dextrose, and 40% the freezing point depression. So I'd start by using dextrose / glucose powder at 50% the quantity of the syrup, by weight.Reply

  22. Hey, just found this blog, and spent most of the night pouring over it. Great job!
    I found you because I'm on a search to better understand ice cream, specifically for the purpose of perfecting a sugar free version to fit into a ketogenic diet. There's nothing at all worthwhile to purchase commercially, nor can I find anything outside of mommy blogs and their "mason jar no churn ice cream"
    I'm a chef myself, and have a professional kitchen and a lot of proper tools, so I want so be able to produce a professional grade product. Unfortunately I don't have the knowledge base to understand how to make a truly palatable texture without any sugar (including naturally occurring from dairy). I'm talking absolute minimal carbs, the lower the better, so I'd love to hear your thoughts.Reply

    • Thanks for writing, chef. I'm gradually learning a bit about sugar-free ice creams, largely because so many questions about them are coming in. Right I now I just have a few thoughts for you: 1. Some of the sugar alcohols, especially erythritol, make excellent substitutes because because they taste pretty close to sugar and have good freezing point depression. But you want to go easy, because too much can cause digestive distress (you don't metabolize these ingredients, but your gut bacteria go to town on them). 2. Low-sugar ice creams (with much of the sugar replaced by sugar alcohols) are much easier to make well than no-sugar ice creams. 3. Make sure to get the total solids up to the right levels. Nonfat dry milk is your best friend. 4. Do a deep search on Pub-Med or Google Scholar, and let the scientists convince you to get off the ketogenic diet before you do yourself any harm!Reply

      • Thanks for the quick reply! Just a few follow-ups directly related to your answers:

        1): erythritol is my go to sweetener, so that's good news. I find I tolerate it quite well, so I'll stick with it as a first choice. It's not quite as sweet as sugar though, so how will the fact that I'm adding more volume to match sugar content affect the end product from a total solids point of view? 2) understandable, I'll play around with minimum ratios. Dairy is already a big source of sugars, so if I'm going to try to make some sorbets or other non dairy options it may allow me to add back some sugar to adjust freezing points. Can you advise on which fats have the best (lowest) freezing temperatures so that I could increase the richness without dairy? 3)if I'm sticking with a dairy based ice cream, but don't want to add milk powder because of the high sugar content, is there any other option that would work well to get total solids up without adding carbs in the form of either sugars or starches? 4) thanks for your concern on this. I've honestly spent the last 6 months trying to find a concrete, evidence based argument against the keto diet, as I was very skeptical at first. Typically people argue that it's not a magic pill, and that you can't live on bacon and cheese. This is unfortunately what most people (including many that adhere to the diet) believe the diet consists of. In reality,if you're doing it correctly, you're eating a wheelbarrow full of vegetables ever day, some lean, organic protein, and a good amount of healthy fats (not a bag of pork rinds). It's definitely not a diet for everyone, as it requires planning, some minor micronutrient supplementation, and at the end of the day is still bound to the calories in, calories out equation. I just find it easier to stick within my caloric needs by eating this way, and I'm eating far more whole foods that I was before I started. All this being said (sorry for the rant) I'm very interested in any sources you can point me towards that would show me reasons that I should reconsider the diet as a long term lifestyle. As I simply haven't been able to find anything I've been satisfied with.Reply

        • Hi Matt, sorry for the slow reply … your comment caught us right in the middle of transition from the old blog site, so it got delayed and also the formatting is little messed up. We’re trying to fix. In the mean time … 1. erythritol’s challenge is that that it has relatively low sweetness (POD 0.65) and high freezing point depression (PAC 2.8). So at normal sweetness levels, you’ll tend to have very soft ice cream. This is one reason it’s often used with other sweetners. 2. and 3. You might consider inulin (technically a starch). It has fairly low sweetness, fairly low freezing point depression, but excellent fat-like textural properties. It behaves like a much larger quantity of solids. And is essentially non-caloric. Try it at 4-7%. 4. Concerns with the keto diet are that 1) it has poor long-term effectiveness, largely because the near-term gains are mostly from water loss and lean muscle mass loss. And 2) ketosis is an unhealthy metabolic state. Doctors and nutritionists prescribe it as a short-term, emergency intervention. It seems likely that most people on the keto diet aren’t really pushing themselves into ketosis, which makes that less of a concern. but it also raises questions about why they’re doing what they do. I haven’t dug through the peer-reviewed research. Here’s a healthline article with a few citations: https://www.healthline.com/health-news/keto-diet-is-gaining-popularity-but-is-it-safe-121914#8 The final word on this topic is a long way off. Just be careful!Reply

  23. Hello there, and thank you for these incredible articles. Your description of the thyme ice cream by Bajolle has caught my imagination. Do you happen to know, or have an educated guess about the formula for it?Reply

  24. Thanks, T.M. That was a long time ago, and I'm sure I've romanticized it. My best guess is that it was a fairly rich, custard-based ice cream, with the thyme steeped into the mix on the stovetop ... something I might not find especially impressive today, but that was a revelation at the time.Reply

  25. Hi, I have a question about the sugar content of fruits. Do you have a good resource for finding the fructose, glucose, and sucrose break down of each fruit? I find that assuming all the sugar is from sucrose gives too much variation in results. Some of my fruit ice creams and sorbets come out rock hard, while others come out perfect even though they have very similar sugar and total solids percentages.Reply

    • Hi Meg, you're in luck. I just started the series on fruit flavors. Next post is going to include data tables. Stay tuned! It's never going to be an exact science, because every batch of fruit will be different. Even if you test with a brix hydrometer, you'll be working with approximations. But with a little effort you can be sure the results will always be good, even if not perfectly consistent.Reply

  26. Hello again, I am wondering if you know of a good source where I can find the relevant ice cream chemical values for a range of ingredients. Most specifically I am interested in POD, PAC, PAC (sa), MSNF, SNF, Milk Fat, Fat. I am relatively new to the analysis of my ice cream along these lines. I generally operate off the "add more this" or "less that" in a very haphazard way. This is really helping me to quantify this learned experience and a strong resource (book, website, etc) would allow me to forecast results and waste less time when experimenting with new flavors. Thank you for your response and commitment to your blog.Reply

  27. Thanks for all the work that you do to present the science of ice cream making in a clear concise way. that being said what is a good sugar blend using erythritol that makes it somewhat healthier that sucrose and dextrose blend. I am a novice just follow recipes without much deviation but would like to understand the science to pursue my true passion granita. thanksReply

  28. Invert sugar question. Whatever I do I can't get the calculations to fit your PAC and POD values. I checked a commercial brand on amazon. It had 18% water and 95% of the sugar was converted. So I assume Water 18% Sucrose 4.1% Fructose 38.95% Glucose 38.95% Then the PAC and POD for this by weight is PAC=152.1 and POD=97.6 Even when testing other scenarios with more residual sucrose etc I can't get the POD up to 130. When testing the values you have in your table using 15% sucrose and 42.5% fructose and 42.5% glucose and zero water I get PAC=176.5 and POD=117. What am I missing?Reply

  29. 15x100/100 + 42.5x74/100 + 42.5x173/100 = 120 for the POD . I think the '130' value is some sort of mistake brought forward from book to book but never really checked. I only recently realised this myself... Also, it is formally incorrect to give a 'total' molecular mass for a mixture of ingredients, like invert sugar is.Reply

    • You may be correct on this, although it's important to note that the POD of a sugar can only be estimated mathematically. It's an attempt to capture a rather complex sensory phenomenon in a single number. Variables include how quickly the sensation of sweetness builds (and dissipates), and how the sweetness tracks with temperature. It's all determined by giving test subjects different concentrations of sugar water and comparing to some standard. I usually avoid invert syrup, because you also never know how much water is in there, so it's always a guessing game. And it's a pain in the ass to work with. Pastry chefs like it because they always have it.Reply

  30. Also, I think the line on inulin is not completely correct, if I may add my two cents.

    Firstly, inulin is not a starch (a digestible - by humans - glucose polymer) but a soluble fibre (digestible by our gut bacteria) and it's a polymer of fructose molecules. This is the reason why some people cannot tolerate it - it may cause bloating and even diarrhoea.

    Secondly, as there are various types of inulin, their Degree of Polymerisation clearly has relevance both on freezing point depression and on sweetness. In general, for chicory inulin, the Sucrose Equivalence is considered to be about 25, at least the one we get to buy in Italy to make our gelato, so the average molecular weight of the chains is higher.

    Having said that, I agree that inulin works wonders in sorbets and if you can tolerate it is a good addition in any case where you may lack solids, especially if you are not using MSNFReply

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