A Predictive Model To Describe the Effects of Temperature, Sodium Lactate, and Sodium Diacetate on the Inactivation of a Serotype 4b Strain of Listeria monocytogenes in a Frankfurter Slurry

Abstract

A modified Gompertz equation was used to model the effects of temperature (55, 60, and 65ЊC), sodium lactate (0, 2.4, and 4.8%), and sodium diacetate (0, 0.125, and 0.25%) on inactivation of Listeria monocytogenes strain MFS 102 (serotype 4b) in frankfurter slurry. The effects of these factors were determined on the shouldering region (parameter A), maximum death rate (parameter B), and tailing region (parameter C) of microbial inactivation curves. Increased temperature or sodium diacetate concentrations increased the death rate, whereas increased sodium lactate concentrations decreased heat resistance. Complex two-way interactive effects were also observed. As both temperature and sodium lactate increased, the death rate decreased; however, as temperature and sodium diacetate increased, the death rate increased. The effect of the interaction between sodium lactate and sodium diacetate on the maximum death rate varied with temperature. Increases in both acidulants at temperatures above 56.7ЊC decreased the death rate, whereas at temperatures below 56.7ЊC, increases in both acidulants increased the death rate. To test for significant differences between treatments, D-values were calculated and compared. This comparison revealed that, in general, sodium lactate increased heat resistance and sodium diacetate decreased heat resistance of L. monocytogenes. This information is important for reducing and minimizing contamination during postprocessing thermal treatments.Listeria monocytogenes (LM) is responsible for approximately 2,500 cases of listeriosis and 500 deaths in the United States each year (5, 13). LM is a foodborne pathogen of concern because of the high death rate (20%) associated with LM infection and the ability of LM to target particular subsets of the population and to grow under refrigerated food storage conditions (6). In 2003, an LM risk assessment for ready-to-eat (RTE) foods was published by the U.S. Food and Drug Administration (FDA), U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS), and the Centers for Disease Control and Prevention (CDC) (17). According to the assessment, consumption of deli meats and frankfurters (not reheated) is associated with the highest risk of contracting listeriosis on a per serving and per annum basis (17). The presence of LM in RTE foods often is associated with environmental contamination in the postlethality processing and/or packaging area. In RTE food products, postprocessing heat pasteurization can be used to reduce or eliminate LM from product surfaces and/or acidulants can be added to the product formulations to prevent growth of any LM survivors over the shelf life of the product (16).The addition of lactate and diacetate salts to product formulations has been successful in controlling the growth of LM during product shelf life (7, 11); however, the effects of these two food grade chemicals, which are generally recognized as safe and can be used together, on the heat resistance of LM have not been well studied, especially a...

Survival and Growth of Listeria monocytogenes in Broth as a Function of Temperature, pH, and Potassium Lactate and Sodium Diacetate Concentrations

“…Blom et al (3) already showed the advantage of using a combination of lactate and diacetate in sausage and cooked ham to inhibit the growth of L. monocytogenes. Recently, a predictive model to describe the effect of temperature, sodium lactate, and sodium diacetate on the inactivation of L. monocytogenes in frankfurter slurry has been introduced (22). Legan et al (10) developed the model, which describes the growth boundary of L. monocytogenes in ready-to-eat cooked meat products at 4ЊC as a function of the product salt, moisture, potassium lactate, and sodium diacetate concentration, and validated the conditions to prevent the growth of L. monocytogenes, using various cured and uncured products.…”

Effect of partial replacement of potassium lactate and sodium diacetate by natural green tea and grape seed extracts and postpackaging thermal treatment on the growth of Listeria monocytogenes in hotdog model system

“…Schultze et al . () reported that incorporating sodium lactate and SD in the frankfurter slurries had a significant ( P < 0.05) effect on increasing the heat tolerance. In this study, partial replacement of PL and SD with GTE and GSE increased heat sensitivity of L. monocytogenes in low‐ and high‐fat chicken hotdogs (Fig.…”

Effect of preinoculation growth media and fat levels on thermal inactivation of a serotype 4b strain of Listeria monocytogenes in frankfurter slurries

“…Another consideration in this study was that the frankfurter surface study did not include the acidulant salts that were used in the frankfurter slurries. From previous research in this laboratory (Schultze et al, 2006), it was determined that sodium lactate and sodium diacetate a Average values and standard deviations over three replicates for the negative inverse of the slope of the microbial survivor curve; different uppercase subscript letters represent significant differences (Po0.05) for each row.…”