Fermentation (pH) & Drying (aw)
Fermentation and drying are traditional processing procedures that must be done within certain limits to ensure product safety. Hazards that must be addressed in making fermented and/or dried products include the toxin production by Staphylococcus aureus during fermentation, and survival of raw-meat pathogens such as Salmonella during fermentation and/or drying. Decreasing the pH through fermentation and water activity through drying can also make a produce shelf-statble. For some products, the guidance on this page must be followed in conjunction with a heating process. (See Heat Treatment)
Fermented Semi-Dry Sausage Products
The following are articles and reports useful for supporting documentation using drying, dry-curing, or fermentation:
Porto-Fett, A.C.S., C.A. Hwang, J.E. Call, V.K. Juneja, S.C. Ingham, B.H. Ingham, and J.B. Luchansky. 2008. Viability of Multi-Strain Mixtures of Listeria monocytogenes, Salmonella Typhimurium, or Escherichia coli O157:H7 Inoculated into the Batter or onto the Surface of a Soudjouk-Style Fermented Semi-Dry Sausage. Food Microbiology 25(6): 793-801. Click HERE for a copy of this paper.
Hwang, C.A., A.C.S. Porto-Fett, V.K. Juneja, S.C. Ingham, B.H. Ingham, and J.B. Luchansky. 2009. Modeling the Survival of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium during Fermentation, Drying, and Storage of Soudjouk-Style Fermented Sausage. International Journal of Food Microbiology. 129(3): 244-252. Click HERE for a copy of this paper. NOTE: several corrections must be made in this paper (Click HERE for copy of corrections).
Burnham, G.M., D.J. Hanson, C.M. Koshick, and S.C. Ingham. 2008. Death of Salmonella Serovars, Escherichia coli O157:H7, Staphylococcus aureus and Listeria monocytogenes During the Drying of Meat: A Case Study Using Biltong and Droewors. Journal of Food Safety. 28(2): 198-209. Click HERE for a copy of this paper.
Ingham, S.C., G. Searls, and D.R. Buege. 2006. Inhibition of Salmonella serovars, Escherichia coli O157:H7, and Listeria monocytogenes During Dry-Curing and Drying of Meat: a Case Study with Basturma. Journal of Food Safety. 26(2): 160-172. Click HERE for a copy of this paper.
Calicioglu, M., N.G. Faith, D.R. Buege, and J.B. Luchansky. 1997. Viability of Escherichia coli O157:H7 in fermented semidry low-temperature-cooked beef summer sausage. Journal of Food Protection 60(10): 1158-1162. Click HERE for a copy of this paper.
Supporting Documentation for Fermentation at Temperatures of 115 F or Warmer
No time limit is necessary for fermentation done at temperatures of 115 F or higher. Click HERE for supporting documentation
Validating Beef Jerky Shelf-Stability Based on Water Activity (aw)
This study evaluated the use of water activity (aw) as a critical limit for beef jerky in oxygen-free packaging. The critical limit summary includes SOPs for vacuum packaging and relating product yield to water activity and moisture:protein ratio.
Ingham, S.C., G. Searls, S. Mohanan, and D.R. Buege. 2006. Survival of Staphylococcus aureus and Listeria monocytogenes on vacuum-packaged beef jerky and related products stored at 21°C. Journal of Food Protection. 69: 2263-2267. Click HERE for a copy of this paper.
Critical Limit Summary:
Controlling Listeria monocytogenes in Ready-to-Eat Products
Under the USDA’s rule on controlling Listeria monocytogenes (Lm) on ready-to-eat (RTE) meat and poultry products, processors of RTE products must take one or more specific steps to ensure the absence of Lm from their products. In particular, the rule requires processors of RTE meat and poultry products to adopt one of three designated “Alternatives” to control Lm on their products. The Alternatives involve varying levels of control and microbiological testing of food-contact surfaces. In some situations the product composition may be used by processors to use Lm Alternative 2 for their products. Specific product compositions that prevent Lm growth can be found in the paper references below. To see if Lm is likely to grow on your specific product, use the Shelf-Stability Predictor.
Room-temperature storage of some products may cause Lm to die and allow processors to use Alternative 1. For specific products and their compositions, check the second paper reference below.
For more information from USDA about controlling Listeria monocytogenes in Ready-to-Eat products, click HERE for the USDA Compliance Guidelines to control Listeria monocytogenes in post-lethality exposed ready-to-eat meat and poultry products.
Ingham, S.C., D.L.Borneman, C. Ane, and B.H.Ingham. 2010. Predicting growth-no-growth of Listeria monocytogenes on vacuum-packaged ready-to-eat meats. J. Food Protection 73: 708-714. Click HERE for a copy of this paper.
Ingham, S.C., D.R. Buege, B.K. Dropp, and J.A. Losinski. 2004. Survival of Listeria monocytogenes during storage of ready-to-eat meat products processed by drying, fermentation, and/or smoking. Journal of Food Protection. 67: 2698-2702. Click HERE for a copy of this paper.
Critical Limit Summary:
Controlling Staphylococcus aureus in Ready-to-Eat Products
Under vacuum-packaging conditions, Staphylococcus aureus is the pathogen best able to tolerate reduced water activity and increased salt level. Therefore, if S. aureus does not grow on a vacuum-packaged product during room-temperature storage, that product can be considered shelf-stable under those conditions. This research gives critical limits to control S. aureus growth in ready-to-eat products.
Borneman, D.L., S.C.Ingham, and C.Ane. 2009. Predicting growth - no growth of Staphylococcus aureus on vacuum-packaged ready-to-eat meats. Journal of Food Protection 72: 539-548. Click HERE for a copy of this paper.
Critical Limit Summary:
Our Shelf Stability Predictor provides a set of models for predicting the growth of Listeria monocytogenes (LM) and Staphylococcus aureus (SA) on Ready-To-Eat meat products as a function of pH and water activity. Use these tools to help you decide if your product is shelf stable.