Silhouette uses named loggers for logging. So in your application you have a more fine-grained control over the log entries logged by Silhouette.

As an example, in your logging.xml you can set the logging level for the complete com.mohiva namespace to ERROR and then define a more detailed level for some components.

<configuration debug="false">
    <logger name="com.mohiva" level="ERROR" />
    <logger name="com.mohiva.play.silhouette.core.AccessDeniedException" level="INFO" />