Why does soup spoil?

Microbial growth: Microorganisms, such as bacteria, molds, and yeasts, can contaminate soup and cause it to spoil. These microorganisms can grow rapidly in warm and moist environments, which is why it's important to store soup at proper temperatures (below 40°F for cold soups and above 140°F for hot soups).

Enzymatic reactions: Enzymes naturally present in the ingredients of the soup can cause it to break down and spoil. These enzymes can be activated by heat, light, or exposure to air. Cooking the soup and storing it at refrigeration temperatures can help to slow down enzymatic reactions.

Chemical reactions: The chemical composition of certain ingredients may react with oxygen, light, or each other over time, resulting in off-flavors or discoloration. Common chemical reactions that can affect soup include lipid oxidation (which can cause fats to become rancid), Maillard reactions (which can turn brown and result in flavors of cooked or roast), and metal contamination (which can occur from using metallic cookware in acidic soups).

Improper storage: Improper storage conditions, such as high temperature or improper containers, can contribute to soup spoilage.

It's always important to follow package instructions, maintain proper refrigeration temperatures (40°F or below), and keep soup covered while refrigerated to minimize its chances of spoiling.