It's good that you failed replacing +05:30 with blank spaces and too bad you tried.
This is the time zone. Without the time zone, you have the local time but loose the ability to order different events in time if they happen in different places of the globe. As you noticed +5:30 is not a constant, this is the case in your application.
You did not specify your platform, languages and the libraries you use, but in a nutshell, you need to transform all times into
Coordinated Universal Time (UTC)
http://en.wikipedia.org/wiki/Coordinated_Universal_Time[
^] using the time zone information. Depending on your application, you may need need to store time zone information separately in your database, if you need to generate local time for your users. All modern calendar libraries have the features to accomplish it.
—SA