why does cheese smell strong when stored?

The Deep Dive

Cheese aroma intensifies in storage due to the metabolic activity of microorganisms. Fresh cheese contains proteins (casein) and fats that are initially inert. However, during aging or storage, resident bacteria and molds—such as Brevibacterium linens in washed-rind cheeses or Penicillium roqueforti in blues—secrete enzymes like proteases and lipases. These enzymes hydrolyze proteins into amino acids and peptides, and fats into free fatty acids. Certain amino acids (e.g., methionine, cysteine) undergo further biochemical reactions, producing sulfur-containing compounds like methanethiol and dimethyl sulfide, which have powerful odors. Fatty acids can be converted into methyl ketones and other volatiles. Temperature and humidity are critical: warmer storage (above ideal refrigeration) speeds microbial metabolism, while airtight wrapping traps these volatile organic compounds, concentrating the smell. In contrast, fresh cheeses like mozzarella have high moisture and low microbial load, so they remain mild. The complexity of a cheese's scent is a direct result of its specific microbial ecosystem and the duration of ripening.

Why It Matters

Understanding cheese storage chemistry helps consumers distinguish between desirable ripening and harmful spoilage, preventing food waste and ensuring safety. For artisanal producers, controlling microbial activity and environmental conditions is essential to develop targeted flavor profiles, supporting traditional cheese-making economies. This knowledge also aids in designing better packaging that balances aroma containment with moisture control. Culturally, it deepens appreciation for strong-smelling cheeses as culinary delicacies rather than defects, fostering global gastronomic diversity. Additionally, the study of cheese volatiles contributes to broader food science research on fermentation and flavor chemistry.

Common Misconceptions

A common myth is that a strong smell always indicates spoilage and unsafety. In reality, many cheeses are intentionally ripened to develop pungent aromas through controlled microbial processes, and these are perfectly safe to eat. Another misconception is that all strong-smelling cheeses share the same odor profile. In truth, different microbes create distinct scents: washed-rind cheeses like Limburger have sulfury, 'sweaty' notes from Brevibacterium, while blue cheeses offer earthy, piquant aromas from Penicillium roqueforti's methyl ketones. The key is recognizing whether the smell aligns with the cheese's expected character or signals rot (e.g., ammonia-like or putrid odors).

Fun Facts

• Limburger cheese's notorious smell is due to Brevibacterium linens, the same bacteria that contributes to human body odor.
• The blue veins in Roquefort cheese are created by Penicillium roqueforti, which produces potent methyl ketones responsible for its sharp, tangy aroma.