Here's a neat tip from Biggie of Lunch in a Box blog on how to make individual portions in freezer bags:
I operate from more of the spur-of-the-moment approach to cooking, so it’s essential to have a well stocked freezer and pantry. One drawback, though, is that if I’ve frozen food in big blocks, I can’t use just a bit quickly without defrosting the whole thing.
Enter my Japanese-language freezing books. A standard tip for freezing ground foods or thick sauces in small portions is to first put the food into a large freezer bag and press it out as flat as possible, eliminating air pockets. (Making it thin speeds up defrost time due to the increased surface area, and pressing out excess air guards against freezer burn.) Use a long chopstick or ruler to create divisions within the food, forming individual portions. This way when you freeze the entire bag, you’ll be able to quickly break off just as much as you want to use, no more.
Read the entire tip here: Link - Thanks Deborah Hamilton!
Opening / closing the bag brings ice cristals though.