Kroger Co., waging a customer-by-customer fight in a competitive marketplace, on Tuesday reported a 30 percent jump in profit for the third quarter and its best results at stores opened at least a year since 1999.

Cincinnati-based Kroger earned $185.4 million, or 25 cents per share, in the quarter ended Nov. 5, compared with earnings of $142.7 million, or 19 cents, a year ago.

Revenue rose 9.1 percent to $14 billion. Sales at stores opened a year were up 6.6 percent with fuel sales, and 3.7 percent without fuel.

Kroger has stepped up surveys of its customers and the company’s competitors, said David B. Dillon, chairman and chief executive and a Kansas University graduate.

Kroger owns Dillion Stores, which has four stores in Lawrence.