Why does a sandwhich go mouldy?

A sandwich goes moldy due to the presence of moisture, organic materials, and microorganisms. When ingredients like bread, vegetables, or spreads contain moisture, it creates an ideal environment for mold spores to thrive. These spores, which are commonly found in the air, can germinate and grow when conditions are favorable, leading to visible mold growth on the sandwich. Additionally, the lack of preservatives can accelerate this process, especially in homemade Sandwiches.