We’ve been working on fruit flavors for several months now. It’s been a purée of trial and error, scientific research, computer analysis, discovery of new ingredients, and trips to the farmers’ market. Now that good fruit is finally showing up here in the northern hemisphere, we’re ready to share what we’ve learned. 

Why so much wonkyness? Isn’t it supposed to be as easy as buying good fruit from a friendly farmer and throwing it into your trusty all-purpose ice cream base?

Yes it is! If you want it to suck.

But if you want truly great ice cream—perfectly smooth textures and a vibrant, three-dimensional explosion of flavor—it’s going to take some work. Sorry to ruin the party.

What’s Tricky about Fruit

• Fruit adds water. It’s often over 90% water. Extra water causes textural problems in ice cream. Every gram of added water needs to be controlled, one way or another.
• Fruit adds sugars. The amount of sugar and the composition (sucrose, glucose, fructose, galactose, maltose) vary with species, breed, maturity, ripeness, season, and overall quality. These factors impact both sweetness and freezing point depression.
• Some fruit adds pectin. Pectin is a hydrocolloid, much like the gums we use as stabilizers. We need to be able to account for this in order to balance our formulas.
• Some fruit adds acid (citric, malic, tartaric, acetic) that can impact the way milk proteins or stabilizers behave.
• Fruit flavor is subtle. Fruits taste best undiluted. 
• Fruit flavor is muted by fats. Even though many of the aromatic compounds that define a fruit’s flavor are fat-soluble, the full vibrance of fruit is better delivered to our senses by water, with as little fat in the way as possible. 

Our Solutions

• We use piles of fruit. This is expensive, and it exacerbates the first four points listed above. But there’s no way around it. Our ice cream formulas are 40% fruit by weight for most fruits. Less for very acidic fruits (lemon, etc.). Our sorbets are 75% fruit. For comparison, typical professional ice creams are in the 10% to 25% range; sorbets are in the 30% to 50% range. 
• We use only excellent fruit. There’s no place for flavor flaws to hide, so there’s just no point in compromising. If the peaches aren’t awesome, try the nectarines. If the nectarines disappoint, you can always just drink yourself to sleep. 
• Our fruit formulas are very low in fat. Lately we’ve been liking the results with 4.5% milk fat, and no egg yolks. This takes us well into Southern Italian gelato territory. More fat than this, the vibrance of the flavor starts to suffer.
• We add about 2% inulin by weight. This vegetable fiber has properties that can stand in for both sugars and fats. It improves the mouthfeel of low-fat ice creams, and allows the fruit flavors to linger a bit longer on the tongue, but it doesn’t mute the onset of flavor. 
• We use an effective stabilizer blend. For fruit ice creams, which tend to be lower in total solids than other flavors, we aim for around 0.28% of the formula’s water weight. In sorbets, we aim for 0.5% the water weight, and we use a new stabilizer blend that hydrates without any heat.
• We aim for a sweetness level a little higher than what’s normal for our other formulas. But lower than what’s typical. (See Sugars in Ice Cream.) For example (in terms of sucrose equivalence):
    Typical fruit ice creams: 18-22%
    Typical non-fruit ice creams: 14-16%
    Our fruit ice creams: 14%
    Our non-fruit ice creams: 12%
• In order to achieve this low level of sweetness, without sacrificing body or freezing point depression (we aim for 70–75% frozen water at -14°C … more on this in a later article) we have to aggressively use sugars that add bulk, have relatively low sweetness, and high freezing point depression. Our choices include:
    -Dextrose (75% the sweetness of sucrose, 190% the freezing point depression)
    -Atomized Glucose Powder DE 40 (34% the sweetness of sucrose, 78% the freezing point depression)
    -Trehalose (20% the sweetness of sucrose, 100% the freezing point depression)
    -Erythritol (65% the sweetness of sucrose, 280% the freezing point depression)
    -Skim Milk Powder (yes, it’s 54% lactose—a sugar)  (8% the sweetness of sucrose, 53% the freezing point depression)
    -Inulin (mentioning again because it has both sweetness and FPD (10% the sweetness of sucrose, 65% the freezing point depression)
• We use a good blender. A Vita Mix / Vita Prep or the equivalent spins 5 to 10 times as fast as a conventional blender. It makes perfectly smooth fruit purées that don’t need to be strained. These blenders are also useful for dispersing the solid ingredients, and for homogenizing the mix after it’s cooked.

Take this advice, and we promise you’ll make the best fruit ice creams you’ve ever had. Or double your money back.

What’s Next

• More totally un-fun, scientific homework about fruit, including data tables, pectin, acids, the Brix scale (along with how to use a hydrometer to measure your fruit and annoy your grocer)
• Sample fruit ice cream recipes, why they work, and how to construct your own
• Sample sorbet recipes, why they work, and how to construct your own