This post is part of The Raptor Lab’s Food Week. Read #jurassickitchen for more!
I started reading scientific studies about ice cream and was initially baffled that quite a few of them used samples with <10% butterfat content. By the U.S. Department of Agriculture’s standards, ice cream isn’t ice cream unless it contains a minimum of 10% fat.
But despite the legality of whether or not they were actually testing ice cream or “ice milk,” as <10% ice cream used to be called, the decision did make sense because they’re mainly looking to replace butterfat.
Let’s look at why this is (supposedly) necessary and a complex problem.
Butter Me Up
First of all, butterfat is a desirable ingredient. Fancy-pants ice creams shoot far past the minimum and toe the max of 20%. Toscanini’s of Cambridge, MA, doesn’t advertise their mix, but brother company (and by that, I mean the owners are brothers) Rancatore’s owns up to their 14% butterfat base. The notorious creameries at the University of Maryland and Penn State are also proud of their 14%. And widely available Ben & Jerry’s and Haagen-Dazs supposedly have higher percentages (speculations put them at 18%, but I found nothing official).
You don’t have to understand ice cream’s chemical composition to feel the difference between a premium ice cream at 14% butterfat and the pocket-friendly 10% variety. Butterfat forms the tasty framework for ice cream’s smooth texture.
During mixing, solid and liquid fat droplets are ideally dispersed throughout the mix. To keep droplets from stabilizing into separate entities, ice cream makers may add an emulsifier (like egg yolk) that will sabotage the surface structure of a fat droplet. Emulsifiers will make each droplet prone to reattaching and bonding to each other and forming a network.
The fatty network traps and stabilizes water content and air bubbles – and there’s a lot of the latter, since air usually composes about 50% of ice cream’s total structure (to keep it from being a heavy impenetrable block of flavor).
So basically, butterfat is the big kahuna in determining how creamy, smooth, and light your scoop turns out.
Now, butterfat is the fat naturally present in milk and is a mouthwatering blend of controversial saturated fat acid chains (triglycerides) and unsaturated fats — and it does pack a hefty calorie count, so even premium ice creams that don’t add sugar to the mix will make weight-watchers nervous.
This leads to the problem of creating a less fatty ice cream while retaining a silky smooth texture and, of course, that delightful taste of high cholesterol.
But the Details Always Get You Right in the Kisser
Most “fat replacers” being investigated include plant-derived oils or the more popular whey protein, which has a similar surface structure to emulsified fat.
Researchers at Uludag University in Turkey and the University of Missouri found that a 6% substitution of total fat with whey protein did not have a huge impact on flavor (though the whey ice cream had less milk flavor and more whey flavor, which ranks high on the “NO SHIT” scale in my book).
Both studies reported relatively unsatisfactory texture, however, and attributed this to over-stabilization — meaning whey did not create as strong a network for all the other ingredients.
Researchers at the University of Guelph in Canada (because apparently that’s where primo ice cream research occurs) believe that the key to finding a good fat replacer is understanding the exact forces that occur when that ever-important fat network is formed. Yes, that’s not quite understood.
The reason that it’s not quite understood is that there are three different types of forces that could be occurring when a fat drop’s surface is destabilized.
First, there’s coalescence, when fat drops grow together and completely lose their identity. Then there’s flocculation, which is when fat drops attach together without losing their identities, which means they can easily break apart into their individual globs again.
But Guelph researchers point to partial coalescence as the main force, which is basically flocculation, but permanent, thanks to solid fat crystals acting as shish kabobs between drops or excess liquid fat cementing them together.
In one of the studies they performed to come to this conclusion, researchers compared samples containing various degrees of saturated and unsaturated oils.
They found that saturated oil created fat droplets that would stick together but could not form larger networks. Unsaturated oil did create large networks. The plant oil droplets in the unsaturated samples were needle-shaped rather than round, which could interact in partial coalescence rather easily.
And because the unsaturated samples seemed to have a fairly high potential to hold and maintain air pockets, there’s a chance that maybe – weirdly, surprisingly — the smooth creaminess of fat-free or reduced-fat ice cream just may lie in a network of pointy, stabby needles.