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Impact of Milk Preacidification with CO₂ on the Aging and Proteolysis of Cheddar Cheese^*

Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853

Corresponding author: D. M. Barbano; e-mail: dmb37{at}cornell.edu.

To determine the influence of milk preacidification with CO₂ on Cheddar cheese aging and proteolysis, cheese was manufactured from milk with and without added CO₂. The experiment was replicated 3 times. Carbon dioxide (approximately 1600 ppm) was added to the cold milk, resulting in a milk pH of 5.9 at 31°C in the cheese vat. The starter and coagulant usage rates were equal for the control and CO₂ treatment cheeses. The calcium content of the CO₂ treatment cheese was lower, but no difference in moisture content was detected. The higher CO₂ content of the treatment cheeses (337 vs. 124 ppm) was maintained throughout 6 mo of aging. In spite of having almost one and a half times the salt-in-moisture, proteolysis as measured by pH 4.6 and 12% trichloroacetic acid soluble nitrogen expressed as percentages of total nitrogen, was higher in the CO₂ treatment cheeses throughout aging. The ratio of _s-casein (CN) to para--CN decreased faster in the CO₂ treatment cheeses than in the control cheeses, especially before refrigerated storage. No difference was detected in the ratio of ß-CN to para--CN between the control and CO₂ treatment cheeses. Intact _s- and ß-CN were found in the expressible serum (ES) from the CO₂ treatment cheese as well as _s1-I-CN, but they were not detected in the ES from the control cheese. No CN was detected in the ES from the curd before the salting of either the control or CO₂ treatment cheese. Higher proteolysis in the cheese made from milk preacidified with CO₂ may have been due to increased substrate availability in the water phase or increased chymosin activity or retention in the cheese.

Key Words: Cheddar cheese • carbon dioxide • proteolysis

Abbreviation key: ES = expressible serum, MOSA = method of standard additions, SNPTN = soluble nitrogen as a percentage of total nitrogen, TA = titratable acidity, TN = total nitrogen, USMC = unsalted milled curd

This article has been cited by other articles:

				B. K. Nelson and D. M. Barbano Yield and Aging of Cheddar Cheeses Manufactured from Milks with Different Milk Serum Protein Contents J Dairy Sci, December 1, 2005; 88(12): 4183 - 4194. [Abstract] [Full Text] [PDF]