A 55-year-old man presents with pale, oily stools and generalized pruritus after recovering from an episode of obstructive jaundice due to a gallstone in the common bile duct. Laboratory studies show elevated alkaline phosphatase and direct bilirubin consistent with cholestasis. Despite removal of the obstruction, he continues to experience steatorrhea. Which of the following processes is most directly impaired, leading to his persistent fat malabsorption?