API'S REST Results: Sabe in Cassandra/MongoSB or cache un Redis?

I need to consume many API's (Twitter, Reddit ...) and show the result on the front of my website.

For example: Get all tweets with #reddit hashtag and show them on the web.

Two ideas in my mind: Save these results in NoSQL and update on every API call or temporarily cache the results of the calls

Possible problems if I use DB: Many accesses to the database

Possible problems if I use Redis: Not enough memory to store all the results of the API calls.

How do you guys/girls see it?