I like the idea of the name being quite abstract or not necessarily self explanatory. Because the product will be visible through the packaging I don't think it is necessary to have the branding saying 'rice' for example.
Portion translated into French. French is quite a recognisable language to all and easily translatable so the word wouldn't be completely obscure, however would add a twist to it.
one: relating to the idea that every tube has one portion in it.
Just right, meaning that the amount of rice you will use will be just the right amount.
One by one, meaning that you can decide yourself how many people you want to cook for.
I think 'un a un' is my favourite so far. It makes sense and is easy to work out for the audience. The logo could work well being symmetrical as well.
Even the name 'one' or '1' or '1by1'.
After seeing the type on a page I have decided that I will be having 'one' as my brand name.
I think it is very self explanatory, relating to one portion of rice in each tube.