How do bacteria cause protein-rich foods such as meat to spoil?

Bacteria cause protein-rich foods like meat to spoil through a process known as putrefaction. During this process, specific bacteria—such as Proteus, Pseudomonas, and Clostridium—break down the long peptide chains that make up proteins into individual amino acids.1

As these bacteria continue to degrade the proteins, they produce various foul-smelling compounds, including amines, ammonia, and hydrogen sulfide. In anaerobic environments, such as inside canned goods, this decomposition can also lead to gas production, which may cause containers to swell or burst. These microbial activities result in detrimental quality changes, including unpleasant odors, discoloration, and altered physical textures, rendering the food unfit for consumption.123