Spoilage potential of Bacillus isolated from cooked sausage: Bidirectional verification from in vitro to in situ

Abstract

Understanding the role of common microorganisms in the spoilage of cooked sausages is essential for developing effective preservation strategies. In the framework of this study, six potential spoilage microorganisms were isolated from spoiled cooked sausages, identified through morphological, physiological, and genetic analyses as Bacillus cereus (two strains), Bacillus safensis, Bacillus altitudinis, Bacillus megaterium, and Bacillus infantis. All isolates exhibited significant protein or lipid degradation activities, except for B. infantis. The spoilage potential of Bacillus was systematically evaluated using a cooked sausage inoculation model in situ based on physical, chemical, and biological changes. Results indicated that Bacillus rapidly colonized cooked sausages, accelerating protein and lipid degradation and thereby deteriorating appearance and texture. Additionally, 74 volatile organic compounds (VOCs) were identified in both Bacillus-inoculated and control samples, revealing that Bacillus transformed aroma compounds such as terpenes into off-flavor compounds like alcohols, aldehydes, and acids (e.g., 1-octen-3-ol, nonanal, and phenylacetic acid). Correlation analysis confirmed the association of Bacillus with spoilage characteristics and VOCs evolution. This study elucidates the spoilage potential and mechanisms of Bacillus in cooked sausages, providing a foundation for developing an effective quality control strategy.