Learn French: Le café sent bon pendant que nous finissons le mixage. - The coffee smells good while we finish the mixing.

Normally, you use adverbs like bien to describe verbs. However, certain verbs take an adjective that acts as an adverb, and sentir is one of them. When used this way, the adjective is invariable, meaning it stays masculine singular regardless of the noun. So it is always sent bon, never sent bien.

Could I use pendant here instead of pendant que?

No, because pendant must be followed by a noun or a pronoun, like pendant la pause (during the break). Since the second part of the sentence introduces a full clause with a subject and a verb (nous finissons), you must use the conjunction pendant que (while).

Why doesn't pendant que trigger the subjunctive mood here?

Pendant que simply states a factual event happening simultaneously, so it takes the regular indicative mood (nous finissons). Learners often confuse it with avant que (before) or jusqu'à ce que (until), which do require the subjunctive because they express an anticipated or uncompleted event.

Would I use le mixage to talk about mixing ingredients in the kitchen?