changed sentence foundry, foundry selector and textClass serialization
diff --git a/lib/KorAP/Document.pm b/lib/KorAP/Document.pm
index 200258a..6153463 100644
--- a/lib/KorAP/Document.pm
+++ b/lib/KorAP/Document.pm
@@ -181,10 +181,14 @@
     };
   };
 
-  foreach ('author', 'text_class') {
+  for ('author') {
       $hash{_k($_)} = join(',', @{ $self->$_ });
   };
 
+  for ('text_class') {
+      $hash{_k($_)} = join(' ', @{ $self->$_ });
+  };
+
   return \%hash;
 };