Use auto filters. If you have value like this:

<meta property="og:title" content="WordPress Trunk" />

Then auto filter is created like this:

og_ + (word before “:”) + _ + (word after “:”) + _value

In this case:

og_og_title_value

add_filter('og_og_title_value', 'my_og_og_title_value');
function my_og_og_title_value($title)
{
    if ( is_home() ) {
        return __('This is extra home title!', 'translate-domain');
    }
    return $title;
}