The best-before or expiry date on your label is a promise. Retailers, food authorities and export buyers increasingly ask how you arrived at it, and “we copied a competitor” is not an answer that survives a complaint, a recall or an audit. Shelf-life testing gives you evidence that your product stays safe and acceptable until the date you print. This guide explains how shelf life is determined, which tests apply to common Pakistani food products, and how to plan a study without wasting months.
Quick answer: Shelf life is determined by storing finished, packed product under defined conditions and testing it at intervals for microbiological safety, chemical changes such as rancidity, physical changes and sensory quality. Real-time studies under normal storage give the most reliable result; accelerated studies at higher temperature give faster estimates for stable products but must be confirmed. The shelf life is the last time point at which every limit is still met, minus a safety margin.
What decides how long a food product lasts?
- Product factors: water activity, pH, fat content, preservatives and initial microbial load
- Process factors: heat treatment, hygiene, filling conditions and cooling
- Packaging: oxygen and moisture barrier, light protection and seal integrity
- Storage and distribution: temperature, humidity and handling, which in Pakistan often include summer heat well above label assumptions
Packaging is often the deciding factor. Our guides to oil and ghee packaging and spices packaging show how barrier choices affect shelf life.
Which tests are used in a shelf-life study?
| Product type | What usually limits shelf life | Typical tests |
|---|---|---|
| Edible oil, ghee, snacks | Oxidative rancidity | Peroxide value, free fatty acids, sensory |
| Dairy and juices | Microbial growth, souring, separation | Total plate count, yeast and mould, pH, sensory |
| Frozen foods | Freezer burn, texture, temperature abuse | Microbiology, moisture loss, sensory |
| Spices and dry mixes | Moisture uptake, loss of aroma, moulds | Moisture, yeast and mould, volatile oil, sensory |
| Bakery | Staling and mould | Moisture, water activity, yeast and mould |
Where a product falls under PSQCA’s compulsory list, the relevant Pakistan Standard sets quality limits the product must meet throughout its shelf life, not only on the day it is made. See our guides to PSQCA certification for edible oil and ghee and dairy products.
Real-time or accelerated shelf-life testing?
Real-time testing stores the product under its intended conditions and tests it until it fails or passes the target date plus a margin. It is the most reliable method and is expected for chilled and perishable products, but it takes as long as the shelf life itself.
Accelerated testing stores samples at raised temperature, and sometimes humidity, to speed up chemical changes, then estimates shelf life at normal conditions. It suits shelf-stable products where oxidation or moisture uptake dominates. It does not predict microbial spoilage reliably, and its estimate should be confirmed by real-time data on the same product.
How do you plan a shelf-life study?
- Define the product and pack exactly as it will be sold: recipe, process and packaging material.
- Identify what will fail first, using the product type and any past complaints.
- Set acceptance limits for each test, based on standards, buyer specifications and sensory panels.
- Choose storage conditions that reflect real Pakistani distribution, including summer temperatures.
- Test at planned intervals using enough samples from more than one production batch.
- Set the date with a margin and repeat the study when the recipe, process or packaging changes.
Use a competent laboratory, ideally one accredited to ISO/IEC 17025 for the tests you need. Our QC laboratory reference explains which tests you can run in-house and which to outsource.
How does shelf life fit into food safety certification?
ISO 22000, FSSC 22000 and HACCP auditors expect your shelf-life claims to be validated, and food authorities can question unsupported dates during inspections. Read our guide to ISO 22000 and HACCP certification and, for Punjab, the Punjab Food Authority licence.
Frequently asked questions
How is the shelf life of a food product determined?
By storing packed product under defined conditions and testing it at intervals for microbiological, chemical, physical and sensory changes. The shelf life is the last point at which all limits are met, minus a safety margin.
What is accelerated shelf-life testing?
A study that stores samples at higher temperature, and sometimes humidity, to speed up chemical changes and estimate shelf life faster. It suits shelf-stable products but should be confirmed by real-time testing.
Which test shows rancidity in oil and ghee?
Peroxide value and free fatty acids are the usual chemical indicators of rancidity, supported by sensory evaluation.
Do I need to repeat shelf-life testing if I change packaging?
Yes. Packaging affects oxygen, moisture and light exposure, so a change in material or format can change shelf life and should be validated again.
Should shelf-life tests be done by an accredited lab?
Using a laboratory accredited to ISO/IEC 17025 for the relevant tests gives results that buyers, auditors and regulators are more likely to accept.
How CEC can help with shelf-life testing
Connect Engineers & Consultants helps food manufacturers design shelf-life studies, set test limits, select accredited laboratories and set up in-house QC testing. See our laboratory compliance service.
Need evidence behind your expiry date? Tell us about your product and packaging and we will propose a study plan.
Testing requirements depend on the product, applicable standards and buyer specifications. Confirm limits with the relevant standard, regulator or buyer. This guide is general information, not professional advice.
