Complex sentence: The herrings are ripened for a couple of days in oak barrels in a salty solution, or brine the pancreatic enzymes which support the ripening make this version of salt herring especially mild and soft.
Split into simpler sentences: The herrings are ripened for a couple of days in oak barrels in a salty solution, or brine. The pancreatic enzymes which support the ripening make this version of salt herring especially mild and soft.