(July 16, 10:53 a.m.) Michigan’s Plum Market stores display the NSF Shop Fresh mark, a sign of the Orchard Lake, Mich.-based company’s recent certification from NSF International, Ann Arbor, Mich.

Plum Markets Corp. operates two supermarkets, one in Ann Arbor, Mich., and one in Bloomfield, Mich. The company plans to open another store in Bloomfield in March 2009, and has plans for a fourth store in Royal Oak, Mich.

To qualify for the Shop Fresh certification and to use the mark, Plum Markets undergo unannounced audits and microbial testing monthly. The stores also use FastCheck, a consumer response program designed to provide immediate response to consumer complaints that could be related to food.

“Myself and the owners, when the company started, felt we needed to have an extra layer in place with all of the food safety scares and to help get the best product to the customer,” said Phil Cassie, director of produce, floral and food safety for Plum Markets.

NSF International is a nonprofit organization that provides certifications and writes standards for food, water and consumer goods.