Keeping the taste consistent in hummus after initial cooking
Fresh-made hummus, without any preservatives added, will usually start to spoil after a couple of hours. This is actually perfectly normal behaviour, as the warm protein and fat rich environment is perfect for some microscopic friends to breed in.

This is actually why restaurant hummus is always so much better than supermarket hummus, which needs to be preserved to last.

The best thing you can do is to refrigerate the hummus immediately, to slow down the activity of the bacteria. 
It may also help to add a bit more lemon juice to make the environment more acid. 

Note that the maximum this will get you is 24-36 hours more. Don't expect it to last longer than that without serious preservatives.