Identifying Bacteria that Cause Spoilage of Fermented Red Hot Pepper Mash

Introduction: Production of hot pepper sauce requires the fermentation of red hot pepper mash in barrels for 2 to 3 years. Some barrels will develop undesired changes in color, texture, and odor. We have isolated the following microbes from spoiled pepper mash Bacillus firmus, Bacillus pumilus, Brevibacillus laterosporus, Enterococcus avium, and Aerococcus viridans.

Purpose: The main goal of this project was to determine which of these strains causes mash spoilage.

Methods: The fresh mash was separated into 7 different subgroups. Subgroups 1 through 5 were inoculated with 10⁷/g of the isolated bacteria individually, the 6^th was inoculated with 10⁷/g of a mixed culture of each isolated bacteria, and the 7^thwas used as negative control.  All containers were incubated at 35°C ± 2°C. All groups were observed daily for changes in odor, color and gas production. Total plate counts were carried out on day 1 and every 15 days for each subgroup.

Results: The counts in the inoculated mash increased during the first two weeks from 1.96 x 10⁶ CFU/g to 1.96 x 10⁹ CFU/g, and then they declined to 2.35 x 10⁷CFU/g on day 60. The non-inoculated mash counts declined from 6.16 x 10⁶ CFU/g to 9.61 x 10³ CFU/g in the first two weeks then increased to 1.51 x 10⁵CFU/g at 60 days. By 30 days the Bacillus species produced a slimy white layer on top of the mash.  On day 60 the odor and a color of the inoculated mash samples were different from the control, especially for Enterococcus avium and Brevibacillus laterosporus.

Significance: E. avium and B. laterosporus were found to be the main cause for the spoilage of the red hot pepper mash. Our results can be used in the development of Good Management Practices to control spoilage of the red hot pepper mash.