A useful 2011 post from our friend Jill Perry Balzano, who now runs Little Lake Orchard in Wells, VT.
Blueberries are on. You'll likely receive some if you have a Workplace Delivery share, but even if you don't, pick-your-own is really the best way to fill your freezer. Check out RAFFL's Locally Grown Guide for a you-pick location near you, grab some large tupperware containers, pile the entire family into the car, and head off into the midst of Vermont's summer abundance. When you return, check out these pointers for preserving your bounty.
You could make syrup or jam, but freezing blueberries is equally delightful because it is simple and extremely rewarding come mid-winter. Though this is one of the more straightforward methods of preservation, there are still a couple of interesting considerations: 1. Should we wash the berries before freezing or afterwards? 2. Should we add anything to the frozen mixture to avoid degeneration of taste and texture?
The US Highbush Blueberry Council recommends freezing blueberries unwashed and washing them once removed from the freezer before use; however, other sources suggest rinsing blueberries first, and patting them dry before putting them in the freezer. To resolve this conundrum, I consulted with RAFFL's Grow-a-Row Coordinator, Garland Mason. Garland, along with some partners in Addison County, is about to freeze ten thousand pounds of blueberries using the Vermont Agency of Agriculture's flash freeze unit. (When you're about to freeze that many blueberries, it's important to have done your homework!) Garland said that they are planning on freezing the blueberries unwashed, and recommended that home cooks rinse and pat dry immediately before use.
Blueberries picked fresh and frozen without any processing or washing usually have decent taste and mediocre, but potentially mushy texture. This is usually fine for muffins, pancakes, and even smoothies, but for pies or anything remotely fresh, you can sometimes detect an off flavor that is the result of oxidation. Impressively, Cooks Illustrated has come up with a solution for overly mushy, off-flavored berries: freeze them with sugar. Sound unusual? According to their extensive taste tests and research, sugar helps to improve firmness by slowing solubility of the berry, and can limit oxidation by coating the berry.
In lieu of all this wonderful information, Everyday Chef is going to offer two options for freezing blueberries: a super-simple method, and a slightly less-simple method that may yield better results.
Super simple method: 1. Spread unwashed blueberries over a (or several) cookie sheet(s), and place in the freezer until frozen (several hours or overnight is recommended). 2. Pour frozen berries into a labeled freezer bag. Remove excess air and seal. Store for up to one year. 3. Rinse berries before use.
Slightly less-simple method: 1. Rinse four pints of blueberries thoroughly, and quickly pat dry--do not dry fully. 2. Toss blueberries with two cups of sugar. 3. Fill plastic bags and, after removing excess air, seal and lay flat onto a cookie sheet in the freezer. 4. After several hours, bags can be removed from cookie sheet and stacked in the freezer. 5. Sugar can be removed by rinsing berries before use.