Expiring the memcache cache for a purticular node

Dear geeks

I am in a situation that, drupal minimum cache lifetime affects my content updates periodically. if any changes made to a node content, it would only get reflected to anonymous users after reaching the minimum cache lifetime(Thats how it should work).
What i am looking for is, need to clear the cached version of the node which  is being updated. I use memcache for caching.

I had gone through the following code, but it won’t expire the cached item.
 

function mymodule_node_update($node) { if ($node->type == 'emergency_update') {  cache_clear_all('content:' . $node->nid, 'cache_content', TRUE);
 }}
Drupal version: 


Source: https://www.drupal.org/taxonomy/term/4/feed