When it comes to gelato, it’s all about the crystals

Staying in Italy spoils you. Farm fresh tomatoes, Pugliese stracciatella and the irresistible summer treat – gelato. In my neighborhood, there is a fifteen year old mom-and-pop gelateria called Pianeta Gelato. The owner, Massimilano, makes fresh gelato every day.

In the afternoon, children finishing school rush to the gelateria and in the evenings, adults assemble at the benches parked outside to enjoy a cone of creamy freshness. In the quiet suburbs, this shop is the epicenter of joy. For the last two years, I have been fascinated with the process of gelato making.

Typically, milk, cream or eggs and sugar are heated up in a vat and pasteurized. According to Massimilano, this step is critical and maximum temperature control is crucial. This base is then cooled, mixed with the flavoring, and transferred to a churning device. The churning allows for incorporation of air while the machine also serves to freeze the gelato rapidly so that the water in the milk freezes.

Ice is crystalline in nature, so the mouth-feel of the gelato strongly depends on the size of the ice crystals. Since gelato is churned at a slower rate than conventional ice cream, the volume of air trapped is lower, thereby making it denser. Hence, we cannot count on the churning to inhibit the formation of large crystals. The rate at which the gelato is cooled down will, therefore, govern formation of larger crystals. That is why ice cream made in liquid nitrogen has a small ice crystal size because of the superfast cooling rate.

A few years back, I was struggling in the lab trying to make nanocrystals out of an amorphous material, so I understand the struggle of trying to control spontaneous crystallization. Of course, the system was very different from milk and water but the two factors I tried controlling were the homogenizing speed and the temperature.

I eventually did not succeed in controlling the crystal morphology but what I find interesting today is that the same logic applies to gelato making. Perhaps that is why the churning-freezing step is automated because it can strongly affect the outcome.
Massimilano also stressed the importance of the quality of the ingredients. He said, “apart from pasteurization, the only thing I am concerned with is the ingredients”.

When asked for some recipe details, Massimilano seemed hesitant discussing the flavors and his vendors. It could have a lot to do with my horrible Italian diction.

What I love about gelato is that in contrast to ice cream, it has a short residence time on your palette. It has a sharp burst of flavor and sometimes two scoops just doesn’t cut it. Moreover, gelato is not served in sweetened cones which makes it completely guilt-free.

Post the coronavirus lockdown, the only treat that was worth the risk was some decadent chocolate with a contrast of strawberry sorbet. Those five minutes were my happiest!

WORDS: Purnima Manghnani

IMAGE SOURCE: Spencer Davis (@spencerdavisphoto)

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