Blueberries. A wonderful little berry – durable enough for easy handling, full of antioxidents and other tasty goodness. Also easy to grow in the Pacific Northwest and one of Sophia’s current favorite foods.
While we have 2 blueberry bushes, they aren’t very old yet, so they only produced a pint or two of berries this year. Fortunately, Laurie’s parents have 4, 14 year old bushes that produce a lot of berries. Fortunately for us, they are happy to share the berries with us. We freeze them and use them through the year. Of course, as our friend Alten Brown points out, the sharp ice crystals created in the normal freezing process rips up cell membranes and leave the fruit "juiced" when defrosted. So he recommends freezing them using dry ice to greatly accelerate the freezing process and thereby reducing the size (and dangerousness) of the crystals.
So, we tried it. After picking and washing about 10 pounds of berries we got just under 10 pounds of dry ice from the Wilsonville Thriftway. Using a small-medium cooler, we crushed the dry ice and mixed it with the majority of the blueberries, filling the cooler completely. It did freeze the blueberries, but there are a few lessons to be learned from the experience to make it go a little better.
# Use a slightly higher ratio of dry ice to blueberries.
# Use a larger cooler to facilitate stirring. In our situation, we needed to better distribute the dry ice to get all the berries equally frozen. Stirring was difficult in the small cooler as the berries quickly got very deep, so we did not stir very much or very deeply.
# Break up the dry ice a little more. After 2 hours there were still some chunks that hadn’t sublimated, and that made bagging a little tricky.
# Make sure to get the dry ice into the corners of the cooler. That was where the majority of the unfrozen berries were.
For results, the berries seem to take less damage by being frozen in this manner. They also seem less likely to be stuck to each other in clumps, and without going through a significant drying process, which can be a little time consuming. Finally, we got to play with dry ice, which is fun anyway.