Microbiological Profile of Dough Systems during Pita Chips, Pretzels and Pretzel Products Production

Introduction: Products with A_w > 0.91 and a pH > 4.5 and < 9.6 may permit growth of Staphylococcus aureus and/or Bacillus cereus and, therefore, potential heat stable enterotoxin formation. Dough systems (A_w > 0.91) used for pita chips, pretzels and pretzel products may have the potential to support the growth of S. aureus and/or B. cereus during routine production. Few dough formulations contain yeast; however, other formulations do not contain yeast. As a result, it is important to understand the effect of dough formulations on the proliferation of S. aureus and B. cereus during routine production conditions.

Purpose: The purpose of this study was to evaluate the microbiological profile of pita chips and pretzel dough systems during routine production conditions from a food safety standpoint.

Methods: Dough samples were collected from commercial pita chips and pretzel facilities. Dough samples were individually inoculated with strains of S. aureus and B. cereus to achieve a target level of 10³ CFU/g. Following inoculation, samples were stored at 25°C and 30°C for pita chips dough samples and 25°C for pretzel dough samples. Samples were analyzed following storage at 0, 1, 2, 3, 4, and 8 days for pita chips and 0, 1, 2, 3, 4, 7, 14, 21, 28 and 35 days for pretzels. Baird-Parker agar, Bacara^® agar, Potato Dextrose agar and Tryptic Soy agar were used as plating media for S. aureus, B. cereus, Yeasts and Total Plate counts, respectively. The experiment was performed in triplicate. Limit of food safety was defined as 10 bacterial multiplications.

Results: The number of bacterial multiplications did not exceed (P < 0.05) the limit of food safety for both S. aureus/ B. cereus in all the evaluated dough types. This was attributed to ‘competitive inhibition’ due to the presence of yeast populations or native flour microflora.

Significance: These findings indicate no significant food safety risk associated with the current production practices. The data generated in this study also provide scientific basis for the facility’s HACCP plan in compliance with anticipated FSMA guidelines.