Microbial Successions Are Associated with Changes in Chemical Profiles of a Model Refrigerated Fresh Pork Sausage during an 80-Day Shelf Life Study

Authors

Andrew K. Benson, University of Nebraska-LincolnFollow
Jalrus R.D. David, ConAgra Foods, Inc.
Stefanie Evans Gilbreth, ConAgra Foods, Inc.
Gordon Smith, ConAgra Foods, Inc.Follow
Joseph Nietfeldt, University of Nebraska-LincolnFollow
Ryan Legge, University of Nebraska-LincolnFollow
Jaehyoung Kim, University of Nebraska-LincolnFollow
Rohita Sinha, University of Nebraska-LincolnFollow
Christopher E. Duncan, ConAgra Foods, Inc
Junjie Ma, University of Nebraska-Lincoln
Indarpal Singh, ConAgra Foods, Inc.

Document Type

Article

Date of this Version

2014

Citation

Applied and Environmental Microbiology p. 5178–5194 September 2014 Volume 80 Number 17

Comments

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Abstract

Fresh pork sausage is produced without a microbial kill step and therefore chilled or frozen to control microbial growth. In this report, the microbiota in a chilled fresh pork sausage model produced with or without an antimicrobial combination of sodium lactate and sodium diacetate was studied using a combination of traditional microbiological methods and deep pyrosequencing of 16S rRNA gene amplicons. In the untreated system, microbial populations rose from 10² to 10⁶ CFU/g within 15 days of storage at 4°C, peaking at nearly 10⁸ CFU/g by day 30. Pyrosequencing revealed a complex community at day 0, with taxa belonging to the Bacilli, Gammaproteobacteria, Betaproteobacteria, Actinobacteria, Bacteroidetes, and Clostridia. During storage at 4°C, the untreated system displayed a complex succession, with species of Weissella and Leuconostoc that dominate the product at day 0 being displaced by species of Pseudomonas (P. lini and P. psychrophila) within 15 days. By day 30, a second wave of taxa (Lactobacillus graminis, Carnobacterium divergens, Buttiauxella brennerae, Yersinia mollaretti, and a taxon of Serratia) dominated the population, and this succession coincided with significant chemical changes in the matrix. Treatment with lactate-diacetate altered the dynamics dramatically, yielding a monophasic growth curve of a single species of Lactobacillus (L. graminis), followed by a uniform selective die-off of the majority of species in the population. Of the six species of Lactobacillus that were routinely detected, L. graminis became the dominant member in all samples, and its origins were traced to the spice blend used in the formulation.