I also have Aloe Vera that I received from a neighbor. They were in a pot and I don't like container gardening, so I transplanted them into the ground with full sun. Mine started turning brown and I read somewhere that Aloe Vera turns brown when in FULL SUN -- are your plants in full sun?
When it turns brown they say it has a sunburn, but it's a desert plant, so I don't understand....
I started growing plants around them, to give them some shade (dappled shade) and that seemed to work. However, this year they've been in full sun, because I didn't plant anything near it to shade the Aloe Vera. So I'm not sure what happened, other than maybe it was it's because my soil has been improving every year, since I chop-and-drop year-round -- I never add soil amendments/fertilizers.
I also never water the plant, since it's a succulent; however, it does, at times, get tons of water from very heavy rains, which we just had over the last two weeks, but that has NOT had any effect, most of the stems have a very healthy green color. There are a couple stems with a little brown, but they're all the old ones and when you look at the plant the green definitely jumps out. However, I've also read that over/under watering can turn them brown, which is probably a bigger issue in containers.
If it is receiving full sun, I would give it a little shade, especially when the sun in directly above. If that's not the issue, than it may have something to do with the containers. Maybe it needs a larger or maybe it's a nutrient/water issue, but I don't know, since I don't container garden.