Food Science and Technology Department


Date of this Version

Fall 9-19-2011


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Food Science and Technology, Under the supervision of Professor Harshavardhan Thippareddi. Lincoln, Nebraska: September, 2011

Copyright (c) 2011 Mauricio Redondo-Solano


The effect of sodium nitrite (NaNO2), sodium erythorbate, sodium chloride (NaCl) and organic acid salts (potassium lactate and sodium diacetate) on C. perfringens spore germination and outgrowth in ham was evaluated. The research was divided in two parts. The first experiment consisted of potential C. perfringens spore germination and outgrowth in ham containing combinations of NaNO2 (0, 50, 100, 150 or 200 ppm) and sodium erythorbate (0 or 557 ppm) during cooling. This experiment included the evaluation of residual nitrite levels as affected by temperature (heat shock at 75°C for 20 min and subsequent cooling from 54.4°C to 4.4°C within 15 h), storage time (3 and 24 h at 5°C) and sodium erythorbate concentration. Inhibition of C. perfringens spore germination and outgrowth was observed after 3 h of ham preparation in all the treatments evaluated. Greater inhibition of C. perfringens was observed with higher concentrations of NaNO2. Addition of sodium erythorbate resulted in greater C. perfringens populations subsequent to 15 h of abusive cooling. Residual nitrite concentrations were similar under the experimental conditions used in this study. Residual oxygen in the ham could explain the inhibition observed during cooling of the ham within 3 h of preparation. During the second experiment, the effect of NaNO2 (0 or 100 ppm), NaCl (1 or 2%) and organic acid salts (Opti.Form PD4®; 0, 1.5 or 2.5%) on C. perfringens spore germination and outgrowth during abusive cooling was evaluated. Incorporation of Opti.Form PD4® (1.5%) inhibited C. perfringens spore germination and outgrowth regardless of the cooling rate (9, 15 or 21 h). Addition of NaNO2 enhanced the antimicrobial activity of organic acid salts. Shorter time period between ham preparation and heat treatment/cooling resulted in greater inhibition of C. perfringens spore germination and outgrowth. Antimicrobial agents should be incorporated into ham formulations in case reductions in NaCl and NaNO2 concentrations are considered in view of the recommendation to reduce sodium content in the diet.

Advisor: Harshavardhan Thippareddi