I don't know if MREs even contain these type of foods anymore, but back in the day...
We used to take the dehydrated fruit. Peaches, pears, mixed fruit, and/or strawberries. Sugar, fruit drink mix, and mre bread.
Then get yourself a large waterbottle.
Place crushed fruit powder in bottle, add several sugar packets, add fruit drink powder, and one MRE bread fill 3/4 or a little better with water and shake.
Then get a rubber glove from your medic and tightly rubberband the glove to the top of the bottle. Store in cool dark place.
The yeast in the bread will reactive with the sugar and start to ferment. The glove is needed to allow the gases to expand, without allowing them to escape.
Let sit for 2-4 weeks, strain and mix with something that tastes better, such as sprite.
So there ya go... mre field booze. I can vouch that it tastes pretty crappy, but it does work.
If you want to take it a step further, you could probably distill it, if you can manage to swipe enough stuff from the motor pool to make a still.
Enjoy.