It began as a simple curiosity: leave a glass of soda out and watch what happens.
Days later, the experiment revealed something more unsettling than spoiled bubbles. The air carried a sharp chemical tang, the liquid hissed and bubbled in strange patterns, and faint shadows seemed to shift beneath the surface. This was not merely old soda—it appeared almost alive, a microcosm of mold and microbial activity asserting itself over a once-fizzy drink.
Coca-Cola, like most soft drinks, is not sterile once opened. Exposure to oxygen and oral bacteria after a sip transforms it into an inviting environment for microbes. A time-lapse video by Photo Owl Time Lapse compared Coca-Cola Original with Coca-Cola Zero, revealing the startling progression of decay.
A Tale of Two Sodas
Two glasses, placed side by side, showcased striking differences. Coca-Cola Original initially remained calm, with ice melting and carbonation fading. By the second week, bubbles formed on the surface, and patches of white and gray mold grew steadily, eventually covering the liquid entirely and turning it into a thick, syrupy sludge.
Coca-Cola Zero, with artificial sweeteners, developed grayish-brown mold spreading outward from the center, resembling a crop circle. As evaporation progressed, the colonies hardened along the glass sides, leaving a starkly different residue than its sugary counterpart.
Why Mold Thrives
Mold needs moisture, oxygen, and nutrients—conditions easily met in an uncovered soda. Even Coke Zero, low in sugar, supported growth due to residual carbohydrates, proteins, acids, coloring agents, and dust.
Experts note that osmophilic molds can survive in low-water, low-nutrient environments, feeding on whatever is available. Without lab testing, the exact species cannot be identified, but the visual impact is clear: carbonated drinks, once opened, can quickly become microbial playgrounds.
Handling and Safety
Pathogenic bacteria rarely survive in soft drinks, but yeasts, acid-tolerant bacteria, and molds flourish. Flat beverages or those containing fruit juice are even more susceptible. Sealed containers remain generally safe; contamination usually occurs due to poor sanitation or environmental exposure. Soda fountains, if improperly cleaned, can harbor mold, E. coli, and other bacteria—underscoring the importance of daily nozzle sanitation and regular maintenance of syrup connectors.
Conclusion
The 100-day time-lapse of Coca-Cola Original and Coke Zero offers a vivid lesson in microbiology: even familiar beverages are vulnerable once exposed to air. Mold, bacteria, and other microorganisms can quickly create complex ecosystems, transforming a harmless drink into a dense, living experiment. Sealed cans and bottles remain low-risk, but opened sodas are a reminder of nature’s persistence—and the importance of proper handling and storage. Even the simplest human creations are no match for microbial life.