A Calendar of Confusion
“BEST BEFORE,” “USE BY,” “DISPLAY UNTIL,” “SELL BY”—our pantries have become a graveyard of conflicting acronyms. In a world where we demand precision, food labeling remains surprisingly unstandardized. This lack of clarity doesn’t just confuse consumers; it’s a leading driver of global food waste. To understand why we are so obsessed with these numbers, we have to look at how we lost touch with the source of our food.
The Evolution of the Date: From Market to Supermarket
The History of Expiration Dates
Before the mid-20th century, food “expiration” was determined by the nose and the eyes. However, as the 1950s ushered in the era of processed, packaged goods, the distance between the producer and the consumer grew. The first “open dating” (dates readable by consumers rather than just coded for retailers) began in the 1970s, largely driven by consumer demand for freshness in an increasingly industrial food system.
The Commodification of Food
As we transitioned from traditional markets—where you knew the baker and the farmer—to massive supermarkets, food became a commodity with a “shelf life.” The date became a proxy for trust. Unfortunately, this shift commodified the age of the food rather than its actual safety, leading to the modern “if in doubt, throw it out” mentality.
Deciphering the Code: What the Dates Represent
It is a common misconception that these dates are “kill dates” after which the food becomes toxic. In reality:
- Best Before: Concerns quality, not safety. The food may lose its crunch or color but is usually safe to eat.
- Use By: Used for highly perishable items (like smoked fish or meat). This is the only date that should be strictly followed for safety reasons.
- Display Until / Sell By: These are stock management tools for retailers, not meant for consumer guidance at all.
Key Takeaway: Most dates are indicators of peak quality as determined by the manufacturer, not a scientific “safety cliff.”
The Science: How are Dates Calculated?
Manufacturers don’t just guess; they use a mix of Microbial Challenge Testing and Accelerated Shelf-Life Testing (ASLT).
By storing food at various temperatures, scientists can calculate the rate of degradation using the Arrhenius Equation:
Where:
- k is the rate constant of the reaction.
- A is the pre-exponential factor.
- Ea? is the activation energy.
- R is the universal gas constant.
- T is the absolute temperature.
This allows brands to predict when a cracker will go stale or when oil will turn rancid under normal kitchen conditions. The video below by Reading scientific services limited (RSSL) highlights the shelf life testing process
What about products without a date?
Many shelf-stable items (like honey or vinegar) or items in some regions (like wine) don’t require dates because they don’t spoil in a way that affects health. For these, the “date of manufacture” is a better metric for quality.
Fresh Fruits and Vegetables
Most fresh produce does not have a date because its “expiration” is visible. Wilted spinach or soft berries are self-evident. Experts suggest storing produce based on ethylene sensitivity rather than a printed calendar.
Citations & References
- NRDC & Harvard Food Law and Policy Clinic (2023). “The Dating Game: How Confusing Food Labels Land Up in the Trash.”
- FDA (2024). “Confused by Date Labels on Packaged Foods?” Food Safety Education Resources.
- Journal of Food Science (2025). “Mathematical Modeling of Lipid Oxidation in Shelf-Stable Commodities.”
- World Resources Institute (2024). “Global Food Waste and the Role of Standardized Labeling.”