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Measurement of pH and Water Activity Values during Ripening of Camembert Cheese

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  036108,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14139) @2003
Authors:   Shaowei Liu, Virendra M. Puri
Keywords:   Camembert cheese, pH, water activity, soft cheese

Listeria monocytogenes is a foodborne pathogen that can survive and grow during ripening of Camembert cheese, a soft cheese. During the ripening phase, the pH and water activity values continually change, which impacts the growth and survival of L. monocytogenes. Toward this end, distributions and changes of pH and water activity during ripening of Camembert cheese (Diameter=108 mm Height=32 mm) were measured at sixteen locations and three vertical crosssections 120 apart. The diameters of probe for pH and water activity measurements were 1.5 and 5 mm, respectively. The pH values increased continually during ripening of Camembert cheese. The top and bottom regions have higher pH values than the intermediate regions. Also, the surface pH values are higher than the center, center middle, and surface middle regions. The range of pH during ripening of Camembert cheese is 4.2-7.5. The water activity values decrease continually during ripening of Camembert cheese. In the top and bottom surfaces of cheese, the water activity value is lower than the inside regions. The range of water activity for the Camembert cheese is 25-80%. The pH and water activity values changed gradually with the ripening time. The pH and water activity values measured in this research will be used to predict the distributions of pH and water activity during ripening of Camembert cheese. These formulations are being used to develop a predictive computational model for L. monocytogenes during ripening of Camembert cheese.

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