THE BLAST FREEZER IN GELATO SHOPS

17/07/2024

How can I organize the work in my gelato shop more effectively, and how can I get the most out of my equipment? This question is answered once again by Andrea Bandiera, an instructor at Carpigiani Gelato University, who explains how to optimize production processes, focusing on a key component of gelato production: the blast freezer. 

The blast chiller is an essential machine for "linking" the work of batch freezer and storage cabinet. The blast freezer is essential for lowering the temperature of the gelato to that of the display case. So if the display case is set to -11°C/ -12°C, the blast chiller should bring the core of the product to -11°C/ -12°C (about 1 h of blast chilling for every 3 kg of gelato). Unfortunately, however, this step creates a very hard surface on the gelato that makes it unsuitable for serving and consumption (and thus for immediate sale). In fact the product needs at least 6 hours of acclimatization in the storage cabinet. The ideal time for this acclimatization process is therefore at night, and it’s during this time that the gelato is brought back up to serving temperature by keeping it in the storage cabinet (which has the same temperature as the display case). 

Once again we can see that this production method, where we work in advance and get organized before the product is made available for sale, is more efficient. Andrea has been working with this method for years and assures us that it doesn’t create any problems from a quality point of view. Indeed, another advantage, though not strictly related to production costs but that is clear to the customer, is that the gelato doesn’t change color due to oxidation in the display case. In fact, the product made a day in advance, frozen in the blast freezer, and then placed in the storage cabinet will oxidize at this stage, not in the display case, where it will instead remain stable from morning to night, without changing color.

Another key to product quality is the overrun. As Andrea is keen to point out, a freshly frozen gelato is placed in the display case at -12°C. Even after a brief chilling in the blast freezer, it takes about five hours (in normal conditions) for the display case to cool the entire mass of gelato in the tray to that temperature. However, during these five hours the product tends to lose overrun, and thus volume. "Thus the single scoop of gelato I put on the cone has a reduced volume, and I have to add more to make up for the loss. So let's assume that about 1 scoop per tray is lost in a day. At the end of the day the gelato artisan has to compensate with 24 extra scoops, which adds up to a big loss over the course of a year."

To remedy this problem, Andrea's suggestion is to properly chill the gelato to -12°C once it’s taken out of the batch freezer. By doing so, the mass of the gelato is "set" due to microcrystallization. If the tray is placed in the storage cabinet overnight, the next morning when it’s put in the display case it won’t undergo any temperature change. “Never forget that to make gelato you need four components: liquids, solids, air, and cold. Cold is an ingredient that must be treated with the same attention that we dedicate to the other three components.”