The Fourth of July is a great time to enjoy fireworks, friends, and food. For me, the Fourth is also a signal to prepare for the impending harvest of blueberries. While I eat as many fresh-off the bush berries I can, freezing is required keep this fruit available year-round. However, it is not as simple as just throwing a bag of berries in the freezer.

The Problem

If a berry takes too long to freeze, then the unfrozen water inside the berry will have time to find existing ice crystals to join rather than creating a new ice crystal. The ultimate result of the longer freezing time is fewer, larger ice crystals that can pierce the cell walls of the berry (this means a soggy, unappetizing blueberry when thawed).

Freezing Blueberries Properly 

The conventional wisdom for proper freezing is to place the berries on a pre-frozen baking sheet in a single layer and freeze down to 0° F before transferring to a plastic bag for long-term storage. But how long before the berries’ centers reach 0°? For good measure, it is advised to freeze a batch overnight (or 12 hours) before moving the berries and starting a new batch. I simply do not have enough baking sheets, space or time to process all my berries using the conventional wisdom. But what to do? Unfortunately, blueberries are not in season yet so I can’t create a series of experiments. And even if they were, have you ever tried sticking a thermometer into a frozen blueberry?

Using SOLIDWORKS Flow Simulation

Instead, I turned to SOLIDWORKS Flow Simulation. Watch the video to see how I not only solved for the proper freezing time based on the size of the blueberry but also came up with a modification to the conventional process to even further improve throughput! I finished by using my results to create a blueberry freezing calculator.

Now all that is left is to have a great Fourth and get out and pick some berries!