Title of Research:
Critical Limits (Water Activity, pH, and Salt Concentration) for
Fermentation and Cooking/Drying of Summer Sausage Products to Ensure
No Growth of Listeria monocytogenes
University of Wisconsin: Madison, WI
Drs. Dennis Buege and Steve Ingham
To study the water activity, pH, and salt concentration
needed to ensure no growth of Listeria monocytogenes during
refrigerated storage of product.
Processing summer sausage and related products to water
activity of less than (<) 0.96, a pH of < 5.3, and at least 4.5%
water-phase salt appeared to effectively allow the processor to
operate under the Alternative 2 with the combination of fermentation
and cooking/drying as the antimicrobial process.
Levels of L. monocytogenes fell rapidly on summer sausage and
related products with water activity of < 0.96, with pH of < 5.3,
and with 4.5% water-phase salt during refrigerated storage with
decreases of 0.6-2.4 logs CFU in the first week of storage. No
growth occurred during the next 3 or 8 weeks. During one week of
room temperature storage, populations fell by 1.6-3.2 logs CFU, and
no surviving cells were detected four weeks later.
The results of this study provide information on process, water
activity, pH and salt concentration that processors can use to
control Listeria monocytogenes in summer sausage and
related products. These parameters are easy to achieve and cost
effective and thus should be of particular value to small and very
small plants that make summer sausage. Plants will, however, need to
validate that their methodology achieves these parameters. This
research should decrease their operating cost while helping them to
ensure food safety and public health protection.
The full report on this research can be found on the Fiscal Year 2003 table under the column Food Safety Technologies - Additional Information.