P2-172 Validation of Muffin Baking Process to Control Salmonella and Determination of Thermal Inactivation Parameters of Salmonella in Muffin Batter

Tuesday, August 2, 2016
America's Center - St. Louis
Jennifer Acuff, Kansas State University, Manhattan, KS
Minto Michael, Kansas State University, Manhattan, KS
Randall Phebus, Kansas State University, Manhattan, KS
Harshavardhan Thippareddi, University of Georgia, Athens, GA
Lakshmikantha Channaiah, AIB International, Manhattan, KS
Amanda Wilder, Kansas State University, Manhattan, KS
Matthew Krug, Kansas State University, Manhattan, KS
Nicholas Sevart, Kansas State University, Manhattan, KS
Sarah Jones, Kansas State University, Manhattan, KS
Sarah Schuetze, Kansas State University, Manhattan, KS
George Milliken, Kansas State University, Manhattan, KS
Introduction: The potential presence and stability of salmonellae in low moisture ingredients, such as flour and milk powders, provide a level of risk in further-processed foods. With new FSMA-related regulatory standards for human food, the validation of baking processes to eliminate salmonellae contamination of ready-to-eat bakery products is required.

Purpose: This study validated a typical commercial muffin baking process as an effective kill-step using a Salmonella cocktail of Newport (ATCC 6962), Senftenberg 775W (ATCC 43845) and Typhimurium (ATCC 14028). D- and z-values in muffin batter were also determined to address variances of baking process parameters.

Methods: Muffins were prepared using inoculated flour (~7 log CFU/g), baked at 190.6°C (oven temperature) for 21 min (mimicking industrial processes), and analyzed by plating samples on selective and injury-recovery media at regular time intervals to determine Salmonella reductions. “Breakpoint” time (when no salmonellae were recovered after enrichment) was determined using an extended baking process. D-values of the salmonellae cocktail in muffin batter were determined using thermal-death-time disks. Randomized complete block designs were used for baking and D-value studies, with three replications as blocks using a = 0.05.

Results: After 21 min of baking, salmonellae counts in the muffins decreased by 6.1 log CFU/g; however, a 5-log reduction was achieved by 17 min. The breakpoint of salmonellae in muffins was 27 min. D-values of the Salmonella cocktail in muffin batter were 62.2, 40.1 and 16.5 min at 55, 58 and 61°C, respectively; the z-value was 10.4°C.

Significance: Baking standard muffins at an oven temperature of 190.6°C for 21 min ensures a >5-log reduction of salmonellae that might be present from contaminated raw ingredients. Presence of inclusions such as fruits, nuts and/or chocolate might impact lethality determinations, prompting additional research. The D- and z-values determined in this study will help processors design appropriate baking parameters to control salmonellae if pre-baking contamination occurs.