How do microorganisms cause vegetables to spoil?

Microorganisms cause vegetables to spoil primarily through a process known as absorptive nutrition. Bacteria, yeasts, and molds—the principal microorganisms involved—contaminate vegetables during harvest, handling, or storage. Once present, these organisms secrete a variety of enzymes that directly digest the vegetable tissue.123

These enzymes break down complex organic molecules, such as the cellulose found in plant cell walls, into simpler molecules that the microorganisms can absorb to fuel their own growth and reproduction. This microbial activity leads to significant degradation of food quality, including the development of off-flavors, loss of nutrients, and deterioration of texture.12

While vegetables are naturally susceptible to spoilage from their own endogenous enzymes—such as those causing browning or vitamin loss—microbial contamination accelerates this decay. Because microorganisms thrive in specific environmental conditions, food processing techniques like blanching, freezing, and pickling are essential to deter this spoilage and extend shelf life.425