SharePoint change browser title

$(document).attr('title', "New Title");

If you have a List to populate title, then read list data and use like this
var bTitle=data from list......
$(document).attr('title', bTitle);

If your browser title is part of search data, then use content search web part.
read data in Item Template.
Ex:
var bTitle= $getItemValue(ctx, "MyTitleColumn").value;
if (!ctx['bTitle'])ctx.bTitle=bTitle;
Bind in Control Template inside AddPostRenderCallback
AddPostRenderCallback(ctx, function()
{
$(document).attr('title', ctx.bTitle);
});