U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Dairy and Functional Foods Research: Wyndmoor, PA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    About ERRC
                        Greetings from the Director
                                    Directions/Lodging
                                    History and Accomplishments
                    Our Work
                        Biomass Pyrolysis Research
                                    IPMP 2013
                                    IPMP Dynamic Prediction
                                    IPMP Global Fit
                                    Pathogen Modeling Program (PMP)
                                    Predictive Microbiology Information Portal (PMIP)
                                    PoultryFARMSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Northeast Area Wyndmoor, Pennsylvania Eastern Regional Research Center Dairy and Functional Foods Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Leggett, Latashaitem
                                            Tomasula, Peggyitem
                                            Van Hekken, Dianeitem
                                            Porto-Fett, Annaitem
                                            Shoyer, Braditem
                                            Luchansky, Johnitem
                                            Renye, Johnitem
                                            FARKYE, N - California Polytechnic State University
  Submitted to: Journal of Food Safety
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 3/13/2012
                                    Publication  Date: 4/1/2012
                                    Citation: Leggett, L.N., Tomasula, P.M., Van Hekken, D.L., Porto  Fett, A.C., Shoyer, B.A., Luchansky, J.B., Renye Jr, J.A., Farkye, N. 2012. Effect of storage at 4 and 10 C on growth of listeria monocytogenes in Queso Fresco. Journal of Food Safety. 32:236-245.Interpretive Summary: Queso Fresco (QF) is a popular, rennet-set, Hispanic-style fresh cheese made from pasteurized milk known for its crumbly texture and non melting properties. However, its high moisture content, near neutral pH and moderate salt content provide the ideal conditions for growth of various bacterial species and pathogens such as L. monocytogenes. Past studies have examined the growth of L. monocytogenes on QF but were typically conducted using retail cheeses of unknown make and handling procedures. In this study, the growth of L. monocytogenes on QF made using a popular make procedure in the U.S. was examined. Spoilage bacteria and other potential pathogens were also identified. This data and a primary model that was created from the data can be used as the basis for food safety assessments, process and formulation improvements, or to monitor the effectiveness of antimicrobials and process interventions in preventing growth of L. monocytogenes on QF.
                                Technical Abstract: A five-strain rifampicin - resistant Listeria monocytogenes cocktail (ca. 3.0 loglOCFU/g) was introduced as a post-pasteurization contaminant in Queso Fresco (QF) that was manufactured using a commercial make procedure.  L. monocytogenes was either inoculated into (IN) the curds before slicing or on (ON) the slices (52 to 66 g), individually vacuum - packaged and stored at 4C and IOC. Growth was monitored for up to 35 days.  Gompertz analyses showed no differences in lag time (LT) because of temperature but growth rate (GR) and generation time (GT) were faster at IOC than 4C.  After 20 days for both the IN and ON treatments, the maximum population density was 7.80 + 0.17 regardless of storage temperature. These results indicate that QF manufacture must be conducted using Good Manufacturing Practices and under hygienic conditions and that the use of antimicrobials and/or or post-processing interventions are necessary to prevent L. monocytogenes growth.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov