Shelf Life After Opening NZ: Supporting ‘Use Within’ Instructions

A multi-use pack needs a clear question about what happens after the first opening. Before printing a use-within instruction, define the use you intend it to cover rather than simply carrying over an unopened shelf-life assessment.

This guide helps New Zealand manufacturers prepare that assessment brief for multi-use packaged retail foods required to bear a label. It provides questions to agree with a competent technical adviser and, where needed, a laboratory—not a ready-made test method or number of days. For broader date-setting background, see our guide to shelf-life testing and best-before or use-by dates.

Shelf life after opening is a different question

The best-before and use-by definitions in Standard 1.2.5, section 1.2.5—2 assume intact packaging and compliance with applicable storage conditions. The practical inference is that evidence limited to those conditions should not automatically be used to justify an opened-pack instruction.

For a specific illustration, FSANZ’s guidance on commercially canned foods explains that opening ends the commercially sterile, sealed condition and that the contents can then deteriorate quickly. That example does not mean every packaged food behaves like a canned product.

We recommend writing two separate questions in the product brief: what supports the unopened date, and what supports the proposed period and conditions after opening? Keep any evidence relevant to both, but identify the limits of its application.

When storage conditions and directions are required

For retail foods required to bear a label, Standard 1.2.1—8(1)(g) requires the relevant storage conditions and directions specified by Standard 1.2.6.

Standard 1.2.6—2, directions and storage conditions covers conditions needed for food to keep until its date mark, and directions needed to protect health or safety. These are conditional requirements: necessary safety directions are not optional marketing copy. The clauses do not supply one after-opening duration or laboratory panel for all foods.

Our recommendation is to treat the desired duration as a proposal until its basis has been reviewed. Agree both the period and the conditions attached to it before finalising artwork.

Prepare an opened-pack assessment brief

The table below is an editorial briefing worksheet. It identifies decisions for product-specific review; it is not an official protocol, compulsory record list or instruction to conduct every possible test.

On a small screen, swipe sideways to view all columns. Keyboard users can focus the table region to scroll horizontally.

Agree the evidence before commissioning more work

Begin by asking the reviewer to assess what you already have. Include relevant validated product or process evidence, not just laboratory reports. Ask for a written explanation of what applies to opened use and what remains unanswered, rather than assuming either that existing evidence is sufficient or that every product needs a new fixed testing programme.

Where microbiological testing is proposed, the FSANZ introduction to microbiological criteria provides a useful principle: the purpose must be clear and the test appropriate. It also explains that criteria relate to a food at a particular point in the food chain.

Apply that principle by asking the adviser and laboratory to agree:

• The specific safety or quality question each assessment will address.
• Which applicable food safety requirements and other acceptance criteria need consideration.
• Who defines and carries out opening, handling, storage and sample submission.
• How any proposed study represents the conditions in the brief.
• How findings and limitations will be translated into a recommendation on wording.

These are questions for agreeing the work, not a sampling method. Do not improvise deliberate contamination or other specialist study procedures from this article.

Checklist before finalising the instruction

We recommend keeping the following together in the product file:

1. Defined scope: the product, process and pack versions covered.
2. Opened-use assumptions: age at opening, repeated handling, reclosure and storage.
3. Evidence review: what existing information supports, its limitations and any further work agreed.
4. Assessment record: the agreed plan, available results, deviations and reviewer’s conclusions.
5. Final wording: the duration, associated conditions and relationship to the date mark.
6. Decision record: who accepted the wording, which artwork version uses it and what changes should trigger another review.

Ask the reviewer to identify any unresolved product-specific question before you treat the proposed instruction as established.

Common planning mistakes to avoid

• Reusing the unopened conclusion without checking its scope. Ask explicitly whether the evidence addresses opened use.
• Considering only packs opened immediately after manufacture. Ask how the assessment covers the opening ages intended by the instruction.
• Ordering a standard panel before defining the decision. Agree what a result would demonstrate before commissioning it.
• Treating a customer’s preferred duration as an established outcome. Keep it identified as a target until reviewed.
• Separating the duration from its conditions. Review the complete instruction, not just the number of days.

How AFVA can help with the brief

AFVA’s shelf-life consulting support includes study planning, storage-instruction review, laboratory coordination, result review and documentation. Where testing is required, accredited third-party laboratories carry it out.

AFVA’s food labelling review service also covers date marking and storage instructions. This article offers consulting support only—not recognised evaluation, verification or product approval. Label review provides comments and recommendations; final label-compliance responsibility remains with the business.

Frequently asked questions

Does every opened-pack instruction need a new laboratory study?

Do not assume that either way. Start with a product-specific review of the existing evidence and its applicability. Ask the reviewer to explain what further assessment, if any, is needed and why.

Can we use the same period across every flavour or pack size?

We recommend listing all variants and asking which are covered by the proposed justification. Do not silently extend a conclusion to versions the review has not addressed.

What if a customer opens the pack close to its use-by date?

Include that question in the brief. FSANZ’s use-by guidance says food should not be eaten after that date. Do not present an after-opening period as permission to continue consuming it beyond the use-by date; agree clear wording with the reviewer.

How many batches, samples and timepoints should we request?

This worksheet does not prescribe them. Ask the technical reviewer and laboratory to propose and justify the design for the specific question, including what the results will and will not support.

What should the review deliver?

We recommend requesting a clear scope, the evidence considered, conclusions, limitations, remaining actions and a recommendation on the proposed instruction. Agree these deliverables before the work begins.

Start with the opened-pack question

Bring the proposed instruction and its intended use conditions together before requesting a quote. A focused brief gives the reviewer a clear decision to address without treating a desired duration as a proven result.

General information only: Requirements depend on the complete food activities, products, processes, locations and sales model. Use current official guidance and confirm the requirements applying to the specific business. This article does not establish a product’s opened life, validate a study method or replace product-specific technical advice.