diff --git a/airflow/dags/EOSC_entity_trasform.py b/airflow/dags/EOSC_entity_trasform.py
index 1bc4c9b..f4a0cb2 100644
--- a/airflow/dags/EOSC_entity_trasform.py
+++ b/airflow/dags/EOSC_entity_trasform.py
@@ -52,8 +52,11 @@ def trasform_product(p: dict) -> dict:
                                   filter(lambda topic: topic.get('topic').get('scheme') == 'FOS', p.get('topics')))))
 
     p['firstPublishDate'] = next(
-        iter(sorted(filter(lambda date: date.get('type') == 'publishing',
-                           [date for m in p.get('manifestations') for date in m.get('dates')]))),
+        iter(
+            sorted(
+                map(lambda date: date.get('value'),
+                    filter(lambda date: date.get('type') == 'publishing',
+                           [date for m in p.get('manifestations') for date in m.get('dates')])))),
         None)
 
     return p