Canned baked beans are used as a convenience food. They may be eaten hot or cold straight from the can as they are fully cooked.
What does as mean here? Does it simply means because? ,to rephrase it;
They may be eaten hot or cold straight from the can because they are already fully cooked.
Basically, if you replace "as" with "because", the global meaning remains the same.
However, in my opinion "because" would be more relevant for a cause-effect relation.
Here, the fact that your beans are fully cooked is not a direct cause of the fact you can eat them hot or cold, it's rather a condition among other possible ones. It's fully cooked, therefore you can eat them the way you want, but it could be for any other reason.
The OP is right; "as" is also used for giving the reason for something (in the sense of "because").
It depends on the context. AS could be used as an adverb, conjunction, and preposition. It more preferable.
Your context, we could use words like
Because is more common than as and since, both in writing and speaking. When we use because we are focusing on the reason.
We can use when to introduce a single completed event that takes place in the middle of a longer activity or event. In these cases, we usually use a continuous verb in the main clause to describe the background event.
We can use as to introduce two events happening at the same time. After as, we can use a simple or continuous form of the verb. The continuous form emphasises an action that interrupts or occurs during the progress of another action.
