■ When you buy frozen vegetables, choose bags whose contents feel as if they are in individual pieces instead of a solid mass. The latter can indicate that the product defrosted at some point and then was refrozen.
■The key to maintaining the quality of frozen goods is keeping them as cold as possible so ice crystals don’t form. Gather frozen items last as you shop, and place them in an insulated carrier as soon as possible.
■Make sure your freezer maintains a temperature of 0 degrees (Farenheit). Even minor fluctuations in freezer temperature can diminish product quality over time.
■ Once a bag of frozen vegetables has been opened, take out what you need and return the rest to the freezer as quickly as possible, pressing out as much air as you can and sealing the bag well, or preferably transferring the contents to a freezer-safe resealable plastic food storage bag and then pressing out excess air before sealing.
Source: The Frozen Food Foundation