Purpose: The purpose of this study was to provide scientific justification that the labelled cooking instructions for dry pasta are adequate to achieve an acceptable reduction in Salmonella spp.
Methods: Fresh pasta dough samples were inoculated with a cocktail of Salmonella spp. to achieve a target level of 8-log CFU/g. Inoculated dough samples were formed into farfalle or fettuccini pasta shapes and dried in a controlled environment chamber, meeting internally established dry pasta specifications. Following drying, samples were cooked at 160, 170 or 180°F and evaluated at several time points between 0 and 25 minutes. Pasta samples were enumerated for Salmonella spp. survival using Tryptic Soy Agar (TSA) with an over lay of Xylose Lysine Deoxycholate (XLD) via pour plate method. Log-transformed data were fitted to a simple regression model using least squares regression to estimate D- and z-values. The validity of the model was verified using R-square values and residual analysis.
Results: The D-values were 3.95, 2.10, and 1.62 min for farfalle pasta, and 3.87, 2.66, and 2.11 min for fettuccini at 160, 170 and 180°F, respectively. At 180°F a >5-log reduction was observed after only 7 min of cooking in both farfalle and fettuccini pasta, far below the recommended labelled cooking instructions.
Significance: The results of this study demonstrate that compliance with labelled cooking instructions will result in an acceptable thermal inactivation of Salmonella spp. on dry pasta. The techniques and methodologies used in this study can provide a scientific basis for food safety plans in the dry pasta industry.