UVM Theses and Dissertations
Format:
Print
Author:
Druart, Marc
Dept./Program:
Nutritional and Food Sciences
Year:
2010
Degree:
MS
Abstract:
Current Food and Drug Administration (FDA) regulations require all cheeses to be manufactured from pasteurized milk unless such cheese has been aged for not less than 60 days at temperatures not less than 35°F. However, milk used to manufacture certain cheese varieties is subjected to a heat treatment equivalent to or higher than' pasteurization during cheesemaking. The manufacture of heat acid coagulated cheese involves heating milk to a high temperature between 80-90°C and the addition of an acid to obtain precipitation of the milk proteins. The 2002 Farm Bill Provision section 10808 (U.S. Department of Agriculture, 2002) has redefined pasteurization as "any process, treatment, or combination of thereof, that is applied to food to reduce the most resistant microorganism(s) of public health significance to a level that is not likely to present a public health risk under normal conditions of distribution and storage." Queso Blanco is a Latin-American fresh soft cheese which is extremely popular in South America and the United States.
The production of Hispanic cheeses in the United States is constantly growing. The aim of this study was to conduct a process evaluation to examine the fate of L. monocytogenes and E. coli 0157:H7 during manufacture of heat-acid coagulated fresh Hispanic Queso Blanco cheese. Results indicate that processing temperatures to which milk was subjected during cheese manufacture resulted in a complete inactivation of L. monocytogenes and E. coli 0157:H7 at initial populations of 10⁷ GFU/ml when subjected to temperatures of 68.1 and 63.9°G respectively. Furthermore, residual alkaline phosphatase fell below the legal limit required by the Pasteurized Milk Ordinance when the milk reached 58.5°C. Overall, the study contains data for process validation of heat acid-coagulated Queso Blanco cheese manufacture to demonstrate a level of safety equivalent to the use of pasteurized milk. These data will provide information which will help to revise the Standards of Identity (21 GFR 133) to include a category for heat acid coagulated cheeses taking into consideration validated process lethality from the manufacturing method.
The production of Hispanic cheeses in the United States is constantly growing. The aim of this study was to conduct a process evaluation to examine the fate of L. monocytogenes and E. coli 0157:H7 during manufacture of heat-acid coagulated fresh Hispanic Queso Blanco cheese. Results indicate that processing temperatures to which milk was subjected during cheese manufacture resulted in a complete inactivation of L. monocytogenes and E. coli 0157:H7 at initial populations of 10⁷ GFU/ml when subjected to temperatures of 68.1 and 63.9°G respectively. Furthermore, residual alkaline phosphatase fell below the legal limit required by the Pasteurized Milk Ordinance when the milk reached 58.5°C. Overall, the study contains data for process validation of heat acid-coagulated Queso Blanco cheese manufacture to demonstrate a level of safety equivalent to the use of pasteurized milk. These data will provide information which will help to revise the Standards of Identity (21 GFR 133) to include a category for heat acid coagulated cheeses taking into consideration validated process lethality from the manufacturing method.