By Chef Joe LaVilla

One of my favorite childhood memories of summer is a Lemon Italian ice. It was syrupy, sweet, tangy and refreshing all at the same time. As I grew up and relocated, I found that it was difficult to find that particular treat. So, putting my knowledge of chemistry and the culinary arts to good use, I found that all it took to emulate my it was the perfect proportion of three common ingredients: sugar, fruit, and water. Oh… and a freezer comes in handy too.

If you’re not a fan of Lemon Italian Ice but find sorbets, Granitas, or fruit bars irresistible, you can apply the same chemistry and ingredients to create these confections.  While these icy treats differ in form and texture, you will find that they are basically the same. The distinguishing characteristics are mainly dictated by the proportions of the ingredients used in their creation and the containers in which they are stored.

The basic science behind making an ice treat is the concept of freezing point. The freezing point of a liquid is the temperature at which the free-flowing molecules begin to organize and form a solid.  While it is not possible to make a liquid freeze at a temperature higher than 32 °F (the standard freezing point of water), it is possible to make it freeze at a lower temperature.

One way to drop the freezing point of water is to dissolve something into it.  This is the theory behind salting the roads in winter. The salt reduces the freezing point of the water (precipitation) turning what would be slippery, icy streets into significantly less-hazardous, wet asphalt. The addition of sugar does the same thing in the preparation of an ice-based dessert. Sugar molecules disrupt the organized structure of the ice crystals effectively lowering the point at which the liquid becomes solid.

Why would you want the freezing point of a sugar-water solution to be low? So that it will stay soft in the freezer. It’s certainly easier to scoop sorbet than an ice cube!

Now that the physics of the matter are out of the way, let’s focus on making some ice-treats. 

First you must decide what kind of dessert you’re craving. Do you want a rich, fruity dessert? Something that resembles scoopable fruit juice? Or, a crunchier fruit-ice? Any of these are possible depending on the liquid, fruit, and sugar ratio you use.

The classic recipe for sorbet combines water, sugar and fruit juice. To determine if the correct amount of sugar has been added, a chef will often float an egg in the solution. If a dime sized portion of the egg floats above the liquid, he has added enough sugar. This is the poor man’s hydrometer, a tool for measuring specific gravity or density. A sorbet made with this method tends to have a good texture, but often lacks a vibrant, fruity flavor.

This is where science helps kick the recipe up a notch; that is, enhance the flavor and “scoopability” of the sorbet using more exact measurements and ratios. For a sorbet to attain the correct texture, it has to have a specific concentration of sugar. That concentration needs to be 15-30% sugar. If the solution is closer to 20-25%, the sorbet will be smooth and manageable upon production, but will need to be tempered if it is left in the freezer.  If the mix is between 30 and 35% sugar, the treat is spoon-ready right out of the freezer. Anything that has a higher concentration of sugar will weep syrup in the freezer and in the bowl.

If you’re looking for a dessert with more “bite”, a Granita may satisfy your palate. It is an Italian-style ice with large, dry, flavorful crystals that is made from a mixture of water and/or juice that has a 15% concentration of sugar. The lower sugar concentration means that the sugar has less of an impact on the formation of ice crystals. During the freezing process, the water and juice are allowed to form larger, sturdier crystals that yield more of a “crunch” when devoured.  The mix is frequently stirred to keep it loose and servable.

So, what’s the guideline? 

Well, for two cups of liquid or liquid and puree, add between 5 to 8 tablespoons of sugar. The variation is determined by the sweetness of the fruit. For a very sweet fruit like a peach, 5-6 tablespoons should do the trick, but a lemon would require about 8 tablespoons. If you are using a fruit puree, it is possible to reduce the amount of sugar because the pectin and solids of the puree will help keep the sorbet soft.  

Also, it is important to note the importance of balancing the sugar with acidity. Typically very ripe fruit is low in acidity and high in sugar. For every two cups of a low-acid fruit puree/juice, it is necessary to add a tablespoon of lemon juice. For high-acid fruits, it may not be necessary to add anything. As for my summer memory, Italian ice is about 35% sugar. That concentration explains the slightly syrupy flavor and consistency.

Mimicking a sorbet from the grocery store would involve taking a cup of fruit puree, adding a bit of sugar and lemon, diluting the mixture to yield 2 cups, and freezing. If you only had juice (or coffee, tea, cocoa), taking a cup of liquid, adding about 11 or 12 tablespoons of sugar and a couple of tablespoons of lemon would result in an ice with a more delicate flavor and texture. 

So if the Ice Cream man doesn’t come around anymore, your favorite childhood treat is only as far away as some fruit, sugar and a freezer.

Read more Food Science secrets here

About Joe LaVilla

Chef LaVilla is the Academic Director for the Culinary Arts programs at the International Culinary School at the Art Institute of Phoenix. Besides being a Certified Executive Chef, Chef LaVilla also holds a certification from the International Sommelier Guild (ISG) as a Certified Sommelier. In addition, Chef LaVilla is experienced in food styling, food and wine pairing, the hospitality industry, culinary arts management, and more.

Before joining The Art Institute of Phoenix, LaVilla had been Executive Chef for Tucchetti restaurant in Phoenix. He has worked for Mark Tarbell as well as Wolfgang Puck. His credits include, “Faculty of the Year” award at The Art Institute of Phoenix; finalist in the Arizona Pork Council Taste of Elegance Competition; and author of the textbook “The Handbook of Wine, Beer and Spirits: A Guide to Styles and Service”.

Chef LaVilla received his Ph.D. in Organic Chemistry from the University of Rochester and his Bachelor of Arts degree, Cum Laude, in Chemistry from Cornell University. He also received an associate’s degree in Culinary Arts from the Culinary Institute of America, where he graduated with honors.