Default value for Picker

I would like to show a default value in the text field of the Picker. So far I know the "Title" is automatically used but I would like to show one of the options, the Picker shows, e.g. the first one.
When creating a custom Picker I could set the "Text" attribute under Android but I would like to have a xaml solution.
Is there a way to specify the default value in a Picker?