Shelf life testing tells you how long your product stays safe and at its best, so the date on the package is evidence rather than a guess. There are two methods. Real-time testing stores the product the way customers will and checks it at set intervals until it fails. Accelerated testing stores it warmer to speed up the changes and estimates the real shelf life from the results, which is faster but only an estimate. What you test depends on what ends your product's life: bacteria and mold for moist or refrigerated foods, rancidity for nuts and oils, staleness for crisp snacks, flavor and color for most things. Below is how to plan a study, a worked example, and how to turn results into a best-by date.
The short version
- Real-time: store as customers will, test at intervals past your target. The reliable answer.
- Accelerated: store warmer to get an early estimate. Confirm it in real time.
- Test for whatever ends the product's life: microbes, rancidity, moisture, flavor, color.
- Plan pull points, samples per pull and the tests at each.
- Set the date before the last passing point, with a margin for rough handling.
- For quality dates, FDA supports the phrase "Best if Used By".
- TaroStack puts the tested shelf life on every batch you make, automatically. More below.
Real-time or accelerated
| Real-time | Accelerated | |
|---|---|---|
| How | Store at normal conditions, test at intervals | Store warmer (and sometimes more humid), test more often |
| Time | As long as the shelf life, and a bit more | Weeks instead of months |
| Answer | What actually happens | An estimate, from a rule of thumb about how temperature speeds change |
| Use it for | Setting the final date | Launching sooner, comparing recipes or packaging |
Accelerated testing often uses a Q10 factor, how much faster a change happens for every 10°C warmer. With a Q10 of 2, a week at 35°C stands in for two weeks at 25°C. The real Q10 depends on the product and what's failing, which is why an accelerated result should be confirmed by a real-time study running alongside.
What to test, by kind of food
| Product | What usually ends its life | Tests |
|---|---|---|
| Chips, crackers, granola | Going stale, going rancid | Moisture or water activity, a rancidity measure, crunch and flavor |
| Nuts, oils, nut butters | Rancidity | Rancidity measure, flavor |
| Baked goods | Staling, mold | Mold check, texture, flavor |
| Fresh salsa, dips, sauces kept cold | Bacteria, yeast, mold | Microbial counts, pH, flavor |
| Jams, shelf-stable sauces | Color and flavor, once safety is set by the process | Color, flavor, pH |
| Coffee, tea, spices | Aroma fading | Flavor and aroma |
For anything where the risk is safety rather than quality (refrigerated, moist, low-acid foods), a lab's microbial testing, or a challenge study where the lab adds organisms deliberately, is the place to start, not a taste panel. For dry and shelf-stable foods, most of the testing is quality, and a lot of it you can do yourself with a careful panel and a scale. Ask two labs for quotes on the lab tests; prices vary a lot by test and region.
A worked study: taro chips
Windward Roots, the made-up taro business I use in these examples, wants a best-by date for its 5 oz taro chips, hoping for 90 days. The plan: store retail bags at room temperature, out of sunlight, and pull three bags at each point.
| Day | Moisture | Crunch (1 to 5) | Rancid flavor (1 none to 5 strong) | Pass? |
|---|---|---|---|---|
| 0 | 1.8% | 5 | 1 | Yes |
| 30 | 1.9% | 5 | 1 | Yes |
| 60 | 2.1% | 4.7 | 1.3 | Yes |
| 90 | 2.4% | 4.3 | 1.7 | Yes |
| 120 | 2.9% | 3.6 | 2.8 | No |
Before starting, they defined failure: crunch below 4 or rancid flavor above 2, scored by the same three tasters on a fresh bag for comparison. Day 90 passed; day 120 failed. Alongside it, bags at 35°C failed at about 8 weeks, which with a Q10 of 2 suggests about 16 weeks at room temperature, roughly in line.
Setting the date
Take the last point that passed and give yourself a margin, because real life is rougher than the study: a hot delivery van, a sunny shop window, a bag opened and closed. With a pass at 90 days and a fail at 120, Windward Roots prints a best by 90 days after the packing date rather than pushing toward 120. Then:
- Print it clearly, with the lot code. Format choices are in best by date format.
- For quality dates, use "Best if Used By". Federal law doesn't require quality date labels on packaged food, except infant formula, and FDA supports "Best if Used By" as the standard phrase (FDA). Your state, or a "use by" for safety, may differ.
- Remember the buyer's side: a store that wants 60 days left at delivery leaves you 30 days to sell a 90-day product, covered in minimum remaining shelf life.
- Re-test when the recipe, the packaging or the supplier of a key ingredient changes.
- Ship the oldest first, so the date you set is the date that gets used: see FIFO and FEFO in the food industry.
This is general information, not legal or food safety advice; a food scientist or your state's food program can help with anything safety-related.
Where this stops working
The study gives you a number; the business has to use it. On paper, the 90 days lives in a report, the best-by is worked out by hand on each packing day, and nobody can quickly say how much stock is within 30 days of its date or which store's minimum it fails. The date you worked hard to set becomes a sticker, and the stock still expires at the back of the shelf.
How TaroStack does it
TaroStack makes the shelf life you tested do its job on every lot, every day.
The tested shelf life goes on every lot. Set an item's shelf life in days, the 90 days from the study, and when you record a batch, the new lot's date is filled in from it, counted from the day the batch was finished. Lots carry your lot code, the supplier's, the production date and the best-by, use-by or retest date, whichever your products use. Lot labels print with the code, the date and a barcode.
The oldest date goes first. Everywhere stock is picked, the lot that expires first goes first. Each customer can carry its own shelf-life rule, so a store wanting 60 days left gets a lot with 60 days left, and planning flags a batch made too early for a customer's minimum before it's made.
And nothing ages unnoticed. TaroStack forecasts what will expire before it's sold and what it'll cost, at the rate each item really sells, and alerts you to expiring lots in the app and by email. If a study ever shows a problem, one report shows which lots went where, so a withdrawal is fast.
| The job | On paper | In TaroStack |
|---|---|---|
| Best-by on a new lot | Worked out by hand | Filled in from the tested shelf life |
| Which lot to ship | Whatever's nearest | Oldest date first, within the store's rule |
| What's getting close | A walk round the shelves | Expiry forecast, with its cost, and alerts |
| A problem found | Search the paperwork | One report, by lot and customer |
Lots, best-by dates, expiry alerts, the expiry forecast and recalls are on every plan, from $49 a month; planning's shelf-life checks are on Standard at $99. The first 30 days are free, with no credit card. If you'd like a hand setting up, ask, and we'll do it with you.