Translation of rennet in Spanish

I'm looking to move to Spain in the summer and hoping to visit my friend in Barcelona before then so I was hoping to have the basics done by then. I've always wanted to learn another language, but we are not pushed enough in the US.
The books had cost only two or three dollars, cheap even for second hand books and after buying them I discovered that these were actually copied books and not used books. It was too late.
At the third or fourth guesthouse we finally took a room. Of course the hot water would not work, and luckily we were upgraded to a terrific, huge room with balcony and garden. It was a very charming place.