Breakdown of Espero que la leche cuaje rápido.
rápido
fast
la leche
the milk
esperar
to wait / to hope / to expect
que
that / than
Questions & Answers about Espero que la leche cuaje rápido.
Why is cuaje in the subjunctive here?
The phrase espero que (I hope that) expresses a hope or wish about a different subject (the milk). In Spanish, expressing hopes, desires, or expectations about someone or something else requires the subjunctive mood in the dependent clause, which is why we use cuaje instead of the indicative cuaja.
I haven't seen the verb cuajar much. Is it only used for food like milk?
While cuajar literally means to curdle, coagulate, or set (used for milk, cheese, or gelatin), it is also widely used figuratively in everyday Spanish. You will often hear it used to mean that a plan, idea, or project comes together, takes root, or catches on (for example, el plan no cuajó means the plan didn't materialize).
Why does the sentence use rápido instead of the adverb rápidamente?
In everyday spoken Spanish, it is very common to use the masculine singular form of certain adjectives as adverbs. Rápido is frequently used this way to mean fast or quickly. You could perfectly well say rápidamente, but rápido is shorter and sounds much more natural in casual conversation.
Since cuajar ends in -jar, are there any spelling changes to worry about in the subjunctive?