Choosing a six-week, six-month or twelve-month shelf life because a similar product uses it is not enough. Your date mark needs to suit your recipe, process, packaging, storage conditions and distribution chain—and it should be supported by evidence.
Shelf-life testing in New Zealand helps food businesses determine how long a product can remain safe and suitable under defined conditions. It also supports the decision to use a best-before date or a use-by date, helps establish storage instructions, and provides records for customers, auditors and verifiers.
Quick answer: how do you set a food shelf life?
Define the product and intended storage conditions, assess relevant safety and quality risks, prepare a study using representative production batches and suitable test points, evaluate the product through and—where appropriate—beyond the proposed period, review the results against pre-set acceptance criteria, then document the justified shelf life and date-marking decision. The exact study and tests must be selected for the specific food.
Need evidence for a new or existing product?
Access Food Verification & Auditing Limited provides practical shelf-life testing support in New Zealand. We can help review product risks, develop a study and sampling plan, coordinate suitable laboratory testing where required, review results and prepare supporting documentation.
In this guide
What Is Food Shelf Life?
Food shelf life is the period during which a product is expected to remain safe and suitable while it is kept in its intact packaging and stored under the defined conditions. Shelf life is not only about whether a product looks or tastes acceptable. It can involve both food safety and product quality.
A product can reach the end of its shelf life because of microbial growth, rancidity, loss of flavour, texture changes, moisture movement, colour deterioration, separation, packaging failure or another product-specific limit. The factor that fails first may determine the practical shelf life.
The New Zealand Ministry for Primary Industries has published guidance on how to determine the shelf life of food. A strong shelf-life decision combines relevant technical information rather than relying on one test result or an arbitrary date.
Best-Before vs Use-By Dates in New Zealand
The correct date mark depends on why the product reaches the end of its shelf life. Under the Australia New Zealand Food Standards Code, a use-by date relates to health or safety, while a best-before date relates mainly to marketability and retention of the product’s specific qualities.
| Point | Best-before date | Use-by date |
|---|---|---|
| Main purpose | Indicates how long the food should remain fully marketable and retain the qualities claimed when correctly stored. | Indicates the date after which the food should not be consumed because of health or safety reasons. |
| After the date | Quality may decline. It can legally be sold after the date if it remains fit for human consumption. | The food must not be sold after its use-by date and should not be consumed after that date. |
| Evidence focus | Quality, suitability and any relevant safety evidence through the stated period. | Safety evidence under the defined storage, packaging and handling conditions, together with relevant quality checks. |
| Typical considerations | Staling, rancidity, moisture change, flavour, texture, colour and overall acceptability. | Potential pathogen growth or toxin formation in foods that may become unsafe before obvious spoilage is detected. |
Do not choose the date mark only from the product category. Two apparently similar foods may require different decisions because their pH, water activity, formulation, heat treatment, hygiene controls, packaging, storage temperature or intended consumers are different.
Important distinction
A product does not become a best-before product simply because the business wants to keep selling it after the date. The date-marking decision must follow the actual safety and quality characteristics of the food and the supporting evidence.
New Zealand Food Date-Marking Rules: Key Points
Most packaged food sold in New Zealand with a shelf life of less than two years requires an appropriate date mark. The detailed requirements are found in Standard 1.2.5 of the Australia New Zealand Food Standards Code.
- Use the words “Best Before” for a best-before date or “Use By” for a use-by date.
- Food must not be sold after its use-by date.
- Bread with a shelf life of less than seven days may use a best-before, baked-on or baked-for date.
- Date-marking information is generally not required where the best-before date is two years or more, except for infant formula products. Individual portions of ice cream or ice confection also have an exemption.
- Where specific storage conditions are needed for the date to remain valid, those conditions must be stated on the label.
- A lot or batch code should still support traceability; it serves a different purpose from the consumer date mark.
The FSANZ guidance on use-by and best-before dates provides a useful plain-language explanation. Businesses should also check whether product-specific standards, customer requirements or other regulatory obligations apply.
How to Determine Food Shelf Life: A Step-by-Step Process
A shelf-life study should answer a defined question: How long will this specific product remain safe and suitable in this packaging, under the stated storage and distribution conditions? The following process creates a more defensible answer.
1. Define the Exact Product
Record the product name, full formulation, ingredient specifications, allergens, processing method, finished-product characteristics, pack size, packaging material, closure or seal, intended storage temperature and instructions for consumers. Include the intended user, especially if the food may be consumed by vulnerable people.
2. Identify Safety and Quality Failure Modes
Consider what could make the food unsafe and what could make it unacceptable. Relevant factors may include pathogens, spoilage microorganisms, pH, water activity, preservatives, oxygen exposure, moisture gain or loss, light, oxidation, enzyme activity, texture, colour, flavour and packaging integrity. Do not assume a formulation has a protective “hurdle” without reliable specifications or measurements.
3. Confirm the Process and Packaging
Shelf-life evidence applies only when the production process is controlled. Cooking, cooling, drying, fermentation, filling, sealing, modified-atmosphere packaging and post-process handling can all affect the result. Packaging should be assessed for barrier performance, seal quality, compatibility and protection throughout distribution.
4. Set the Storage and Distribution Conditions
Define how samples will be stored and how the real product is likely to be transported, displayed and used. A chilled product assessed only at an ideal laboratory temperature may not represent normal temperature variation in the supply chain. Any deliberate worst-case or abuse condition must be technically justified—not improvised.
5. Select Representative Batches and Samples
Use representative production, ingredients, packaging and equipment. Multiple independent batches can help capture normal process variation. The correct number of batches and sample units depends on risk, variability, test method, available evidence and the consequence of failure; there is no universal number that is suitable for every food.
6. Set Test Points and Acceptance Criteria Before Starting
Plan testing at production, suitable intermediate stages, the proposed end of shelf life and—where technically appropriate—a point beyond it. Define in advance what will be tested, how many sample units are required and what constitutes a pass, warning result or failure. This reduces the risk of interpreting results selectively after the study.
7. Complete Testing and Document Sensory Assessment
Complete the selected microbiological, chemical, physical, packaging and sensory checks at the planned stages. Sensory evaluation should use a consistent method, defined attributes and trained or suitably briefed assessors. “Looks okay” is not a strong record.
8. Review Trends, Not Only Final Results
Review the full pattern across batches and time points. A result may meet a limit at the final point but still show an unexpected upward trend or inconsistent batch performance. Investigate unusual results, deviations, damaged packs and differences between batches before confirming the shelf life.
9. Apply an Appropriate Margin and Make the Date-Mark Decision
Do not automatically print the longest period achieved by the best-performing sample. Consider normal process variation, measurement uncertainty, distribution conditions, customer expectations and the consequences of failure. The margin and final date must be justified for the product; a fixed percentage is not suitable for every study.
10. Approve, Implement and Review
Prepare a shelf-life report or technical justification, approve the date mark and storage wording, update the product specification, label and production records, and train relevant staff. Continue monitoring complaints, returns, retains and test results after launch. Shelf life should be reviewed when the product or process changes or when market evidence no longer supports the original decision.
Factors That Can Change a Food Product’s Shelf Life
| Factor | Why it matters | Information to retain |
|---|---|---|
| Ingredients and formulation | Ingredient quality, microbial load, nutrients, salt, sugar, acids and preservatives may affect safety and stability. | Approved recipe, ingredient specifications, certificates and supplier details. |
| pH and water activity | They influence which microorganisms may survive or grow, but must be considered with the complete product and process. | Validated methods, calibrated equipment and representative results. |
| Processing | Heat treatment, cooling, drying, fermentation, handling and post-process exposure affect initial contamination and growth opportunities. | Process flow, critical limits, monitoring records and validation evidence. |
| Packaging | Moisture and oxygen barriers, vacuum or gas atmosphere, seal integrity and pack size may change deterioration and microbial risk. | Packaging specification, food-grade confirmation and seal or integrity checks. |
| Storage and distribution | Temperature, time, humidity, light and handling affect the rate of microbial growth and quality loss. | Storage limits, transport expectations and temperature evidence where relevant. |
| After opening | Opening may introduce contamination, oxygen or moisture and can change the conditions used for the unopened study. | Opening instructions, refrigerated life and consumer-use assumptions. |
What Tests Are Used in a Shelf-Life Study?
There is no standard test panel that is correct for every product. A shelf-stable biscuit, chilled ready-to-eat meal, fermented sauce and frozen dessert have different failure modes and need different evidence. Tests should be chosen from a documented product and hazard review.
| Assessment area | Possible checks | What the results may show |
|---|---|---|
| Microbiological | Relevant pathogens, hygiene indicators, yeasts, moulds or spoilage organisms selected for the product. | Safety, process hygiene, spoilage trends or need for further investigation. |
| Chemical | pH, water activity, moisture, salt, preservative level, oxidation indicators or nutrient retention where relevant. | Whether protective characteristics and quality remain within defined criteria. |
| Physical | Texture, viscosity, separation, weight change, colour, crispness or other product-specific measures. | Loss of expected quality or failure to meet specification. |
| Sensory | Appearance, aroma, flavour, texture and overall acceptability using defined scoring and rejection criteria. | When the product is no longer acceptable or no longer retains claimed qualities. |
| Packaging | Seal integrity, leakage, swelling, corrosion, delamination, vacuum or gas composition where applicable. | Whether the pack continues to protect the product throughout its proposed life. |
Relevant legal microbiological criteria must be considered where applicable. FSANZ explains that Standard 1.6.1 and Schedule 27 set maximum permissible limits for particular microorganisms and food groups, including criteria for Listeria monocytogenes in ready-to-eat foods.
End-product testing has limits
A laboratory result describes the samples tested; it does not replace control of ingredients, cooking, cooling, hygiene, packaging and storage. Higher-risk shelf-life decisions may require specialist input, predictive modelling or a properly designed challenge study in addition to routine testing.
Example Shelf-Life Testing Schedules
The test points should be dense enough to show when important changes occur. The following examples illustrate the structure of a schedule only. They are not ready-made sampling plans and should not be adopted without reviewing the actual product and risks.
| Proposed period | Illustrative test points | Planning note |
|---|---|---|
| 7 days | Day 0, Day 3, Day 5, Day 7 and an appropriate point beyond the target. | Short-life chilled products may change quickly, so intermediate points are important. |
| 4 weeks | Week 0, Week 1, Week 2, Week 3, Week 4 and a justified later point. | The test frequency may need to increase near the expected failure period. |
| 6 months | Month 0, Month 1, Month 3, Month 6 and a justified later point. | Add points where oxidation, moisture movement or another known change is expected. |
| 12 months | Month 0, Month 3, Month 6, Month 9, Month 12 and a justified later point. | Long studies need controlled sample storage, retain inventory and a clear tracking system. |
Real-time testing under representative conditions usually provides the most direct evidence. Accelerated shelf-life testing can sometimes help investigate quality deterioration in suitable products, but it does not automatically predict microbial safety and should not be used without a scientifically appropriate model.
Why Shelf-Life Studies May Test Beyond the Proposed Date
Testing only at production and on the exact proposed final day can leave little information about the rate of change or the effect of normal variability. A technically appropriate later point may help show whether there is a reasonable buffer rather than a result sitting directly on a failure boundary.
However, “extra days” are not a substitute for a sound study. The appropriate margin depends on the hazard, product, process reliability, storage conditions, data variability and test uncertainty. It should be chosen during study design and explained in the final justification.
Can One Study Cover Several Products or Flavours?
Sometimes a product-family approach is possible, but only where the grouping is technically justified. Products should have sufficiently similar formulation, processing, packaging, storage and relevant risk characteristics. The selected representative should be a credible worst case—not simply the flavour that is easiest to test.
For example, a new filling, added fresh ingredient, lower-acid variant, different pack size or changed moisture level may create a different shelf-life risk even when the products share the same brand and base recipe. Record the family rationale and the characteristics compared.
Common Shelf-Life Testing Mistakes
| Common mistake | Better approach |
|---|---|
| Copying a competitor’s shelf life | Generate evidence for the actual formulation, process, packaging and storage conditions. |
| Testing only one convenient batch | Assess whether independent batches are needed to represent normal variation. |
| Sending samples without a written plan | Define the question, hazards, tests, time points, sample units and acceptance criteria first. |
| Using only sensory checks for a safety-limited food | Select safety evidence from a product-specific hazard assessment; unsafe food may not look, smell or taste spoiled. |
| Ignoring packaging and distribution | Use the intended commercial pack and define realistic storage and transport conditions. |
| Extending the date from one acceptable result | Review all batches, trends, deviations, safety criteria, quality results and uncertainty before approval. |
| Keeping reports without a conclusion | Prepare a signed summary linking the evidence to the approved period, date mark and storage wording. |
What Should a Shelf-Life Report Include?
A useful report should allow another competent person to understand what was studied, what evidence was obtained and why the conclusion was reached. Include:
- product description, recipe or formulation reference and product specification;
- process flow, important controls and packaging specification;
- proposed shelf life, intended date mark and storage conditions;
- hazards, quality failure modes and technical rationale;
- batches, production dates, batch codes and sample identification;
- study conditions, test schedule, methods and acceptance criteria;
- laboratory reports and documented sensory or physical results;
- deviations, unusual results, trend review and investigations;
- approved shelf life, date-mark type, storage instructions and supporting margin;
- approval name and date, implementation actions and review triggers.
Keep the final report with the source evidence rather than retaining laboratory certificates alone. This documentation may support your Food Control Plan or National Programme, customer approval, audit evidence, label review and future product-change assessments.
When Should Shelf Life Be Reviewed or Revalidated?
Shelf-life evidence is not permanently transferable to every future version of a product. Review it after:
- a formulation, ingredient or supplier change;
- a change to cooking, cooling, drying, fermentation, filling or another process;
- new equipment, production scale or manufacturing site;
- a packaging material, closure, gas composition or pack-size change;
- a change in storage, transport or distribution conditions;
- a proposed shelf-life extension;
- spoilage complaints, returns, abnormal retains or microbiological concerns;
- new regulatory, scientific, customer or audit requirements.
Businesses launching or reformulating a product may also benefit from new food product development support. Once the shelf life is established, a food labelling review can help check the date mark, storage instructions and other mandatory label information before printing.
How Long Does Shelf-Life Testing Take and What Does It Cost?
A real-time study normally runs for the proposed shelf-life period and may include a justified point beyond it, plus time for planning, laboratory turnaround and reporting. A six-month target cannot automatically be proven by a short test. Accelerated methods may be helpful in some quality-limited products, but they are not a universal shortcut.
Cost depends on the number of products or product families, batches, sample units, time points, storage conditions, laboratory analyses, sensory work and reporting required. A focused product-risk review before requesting laboratory quotes can reduce unnecessary tests and identify missing evidence early.
Shelf-Life Testing New Zealand: Frequently Asked Questions
Is laboratory testing always required to set a food shelf life?
Not in every case. Suitable evidence may include product history, a technically valid previous study, scientific literature, supplier data, formulation and process evidence, predictive tools, laboratory testing and sensory assessment. The evidence needed depends on the product and risk. Higher-risk products commonly need stronger microbiological support.
How many batches should be included in shelf-life testing?
There is no single number for every product. The plan should consider process and ingredient variability, product risk, study purpose, available evidence and the consequence of failure. Independent production batches generally provide stronger evidence than repeated samples from only one batch.
Can I use the same shelf life as a competitor’s similar product?
A competitor’s label may be useful background information, but it does not validate your product. Differences in recipe, raw materials, process controls, packaging, hygiene, storage and distribution can materially change shelf life.
Can accelerated shelf-life testing replace real-time testing?
Not automatically. Accelerated testing may help evaluate certain predictable quality changes where a suitable model exists, but elevated temperatures or other accelerated conditions may create different deterioration pathways. It should not be assumed to establish microbial safety.
Should samples be tested after the proposed shelf-life date?
A justified later point can help show a margin and improve understanding of deterioration trends. The exact period should be selected for the product and risk; passing a later point does not mean the printed shelf life should automatically be extended to that date.
Do unopened and opened products have the same shelf life?
Usually the printed best-before or use-by date assumes the package remains intact and the food is correctly stored. Opening can change contamination, oxygen and moisture exposure. A separate instruction such as “refrigerate after opening and consume within X days” may need its own evidence.
Can one worst-case flavour represent a whole product family?
Possibly, where the products are sufficiently similar and the selected representative is technically justified as the worst case for the relevant safety and quality factors. Document the comparison. A materially different formulation or process may require separate evidence.
Can shelf life be extended after a product is launched?
Yes, but an extension should be supported by suitable evidence. Review existing study results, retains, complaints, returns, process control, packaging, storage and any additional testing needed before changing the date mark.
Who is responsible for setting the best-before or use-by date?
The food business or supplier responsible for the product must ensure the date mark is appropriate and the food is safe and suitable. Laboratories and consultants can provide technical evidence and advice, but the business should retain the justification and control the approved specification.
Can AFVA help arrange shelf-life testing?
Yes. AFVA can review the product, process, packaging and risks; help develop a study and sampling plan; coordinate with a suitable laboratory where required; review results; and support preparation of shelf-life documentation. Laboratory testing is not provided directly unless specifically confirmed.
Need Help Planning or Reviewing a Shelf-Life Study?
Access Food Verification & Auditing Limited provides practical shelf-life support for food manufacturers, bakeries, importers, start-ups, private-label brands and other food businesses across New Zealand.
View Shelf-Life Testing Support Request Free Initial GuidanceGeneral information only: Shelf-life and date-marking requirements depend on the specific food, ingredients, process, packaging, storage, intended use and applicable regulatory requirements. This guide does not replace product-specific technical, laboratory or legal advice.
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