Behavior of Listeria monocytogenes in the Presence of Gluconic Acid and During Preparation of Cottage Cheese Curd Using Gluconic Acid

¹ Department of Food Science and the Food Research Institute, University of Wisconsin-Madison, Madison 53706

Unrestricted or minimally restricted growth of Listeria monocytogenes strain V7 occurred 1) at 13°C in tryptose broth with .125 or .25% gluconic acid or .1 to .3% glucono-delta-lactone, 2) at 13°C in milk with .125 to 1.0% gluconic acid or .5 or 1.0% glucono-delta-lactone, 3) at 35°C in tryptose broth with .125 to .5% gluconic acid or .1 to 5% glucono-delta-lactone, and 4) at 35°C in milk with .125 to 1.0% gluconic acid or .5 to 1.5% glucono-delta-lactone. Limited growth of L. monocytogenes occurred 1) at 13°C with .375 or .5% gluconic acid or .3 or .4% glucono-delta-lactone, 2) at 13°C in milk with 1.5% glucono-delta-lactone, 3) at 35°C in tryptose broth with .75% glucono-deha-lactone, and 4) at 35°C in milk with 2.0% glucono-delta-lactone. Partial to complete inactivation of L. monocytogenes occurred 1) at 13°C in tryptose broth with .75 to 1.5% gluconic acid or .75 or 1.0% glucono-delta-lactone, 2) at 13°C in milk with 1.5% gluconic acid or 2.0 to 3.0% glucono-delta-lactone, 3) at 35°C in tryptose broth with .75 to 1.5% gluconic acid or 1.0% glucono-delta-lactone, and 4) at 35°C in milk with 1.5% gluconic acid or 2.5 or 3.0% glucono-delta-lactone. Milk containing L. monocytogenes was coagulated with gluconic acid, HCl, or rennet, and cottage cheese curd was prepared. After cooking, numbers of the pathogen in curd or whey from rennet-coagulated milk were reduced by ca. 1.5 and 2.5 orders, respectively. Small numbers of survivors appeared in curd but not in whey of HCl-coagulated milk. No survivors were detected in curd or whey of gluconic acid-coagulated milk.

Key Words: gluconic acid • Listeria monocytogenes • cottage cheese

Submitted on July 24, 1989
Accepted on January 19, 1990