how can i convert a date format from PST to UTC

Hello I am trying to convert time object from PST to UTC

time = "2016-08-15 11:51:27 America/Los_Angeles"

What I am trying is:

utc = Time.parse(time).utc

but it doesn't returns the correct time it returns.

# 2016-08-15 11:51:27 UTC

what's wrong here?