Is Your Canning Facility Ready for a Retailer Audit? Time-Temperature Indicators and Documentation
Retailer and supermarket audits are among the most commercially significant quality events a canning or bottling facility faces. A successful audit maintains and can strengthen the commercial relationship with major retail customers. A failed audit — or worse, a product recall triggered by an inadequacy identified during or after an audit — can result in delisted products, contract termination, and reputational damage that extends far beyond a single customer relationship. For facilities that process low-acid canned or bottled foods, the thermal processing documentation that auditors scrutinise most closely centres on one fundamental question: can you prove that every batch you produced received the lethal heat dose required to ensure commercial sterility?
Time-temperature indicators are central to answering that question convincingly. This article explains what retailer and supermarket auditors look for in thermal processing documentation, how time-temperature indicators contribute to a robust audit evidence package, and the steps a canning facility should take to ensure its documentation is audit-ready at any time.
What Retailer Auditors Look for in Canning Facilities
Major UK and European supermarket chains — including those operating under BRC Global Standard for Food Safety, SQF, and FSSC 22000 requirements — conduct technical audits of their supplier facilities on a regular basis, typically annually for high-risk suppliers. For canning and bottling facilities producing low-acid thermally processed foods, the audit scope includes the following thermal processing elements: evidence that scheduled processes have been established by a recognised Process Authority; evidence that retort operators are trained and competent in detecting and responding to process deviations; records of thermal processing monitoring for every batch produced; and evidence that the thermal process monitoring system is validated, calibrated, and fit for purpose.
Auditors are looking for complete, legible, and contemporaneous records — records that were created at the time of processing, not reconstructed from memory or from incomplete data. They are also looking for records that are linked to specific production batches, so that in the event of a recall or customer complaint, the processing history of the relevant batch can be retrieved quickly and completely.
The Role of Time-Temperature Indicators in Audit Documentation
Time-temperature indicators provide per-batch, product-level evidence that the scheduled thermal process was achieved. Unlike retort instrument records (which document the performance of the retort itself), time-temperature indicators placed inside the load document the thermal exposure received at a defined position within the product containers — the position that received the least heat during the cycle, or the closest accessible approximation to it.
This distinction matters in an audit context. A retort that recorded the correct hold temperature and time does not automatically guarantee that every container in the load received the required lethal heat dose. Heat penetration is a function of product density, container size and geometry, pack orientation, container fill weight, and initial product temperature. Only a measurement made inside the load at the critical position can directly verify that the scheduled process was achieved for that specific load configuration.
Time-temperature indicator records, showing the indicator reading for every production run, provide this evidence. A complete set of indicator records for all production batches in the audit period demonstrates that the facility has been consistently monitoring thermal process achievement at the product level — and that any process deviations would have been detected and the affected product placed on hold.
Building a Robust Audit Evidence Package
A canning facility preparing for a retailer audit should ensure its thermal processing documentation package includes the following elements. First, the scheduled process specification: a document from a recognised Process Authority specifying the minimum retort time and temperature for each product type and container size in production, with the basis for the schedule (heat penetration study data, F₀ calculations) included or referenced. Second, the retort monitoring records: computerised or paper records from the retort's temperature and pressure recording instruments for every production run, retained in a format that can be retrieved by batch number. Third, the time-temperature indicator records: completed monitoring forms for every production run, showing the indicator reading, the acceptance criteria, the pass/fail determination, and the batch identification. Fourth, the process deviation handling records: a complete record of any instance where an indicator or retort instrument reading indicated a potential process deviation, the investigation conducted, and the disposition decision for the affected product.
The most common documentation gap identified by auditors in canning facilities is not a total absence of records, but incomplete or inconsistent records — missing batch numbers on indicator records, indicator records that do not match the retort instrument records for the same date, or acceptance criteria that are not documented. Closing these gaps requires a systematic approach to production record design and operator training, not just a response to audit findings.
Indicator Selection and Validation for Audit Compliance
To satisfy BRC, SQF, and equivalent auditor requirements, time-temperature indicators used in production monitoring must be validated for the specific retort process being used. This means demonstrating that the indicator responds reliably to the thermal exposure conditions generated by your specific retort system and process parameters, and that the acceptance criteria (the indicator reading that constitutes a pass) have been established by testing against the heat penetration data for each product type.
Validation documentation should include the indicator product specification and batch certificates, the test data demonstrating indicator performance in your specific retort process conditions, the established acceptance criteria for each product type and retort system, and the storage and handling requirements for the indicators. This documentation should be available for review during the audit and referenced in the HACCP plan.
Operator Training and Competency
Even the best documentation system fails if operators are not trained to use it correctly. Retort operators should receive documented training covering the correct placement of time-temperature indicators in the retort load (location, orientation, and method of attachment), the correct reading and recording procedure after the cycle, the acceptance criteria for each product type, and the procedure for raising a deviation record and placing product on hold when an indicator gives an out-of-specification reading.
Frequently Asked Questions
Which time-temperature indicator products are recognised by BRC auditors for canning applications?
BRC auditors do not specify brand names, but they require that the indicator used is validated for the specific process and that the validation documentation is available. The SteriTec range of batch retort process indicators, available from Temperature Indicators Ltd, includes product specifications, batch test certificates, and application guidance documents that support the validation package requirements of BRC, SQF, and equivalent standards. Contact us for documentation to support your audit preparation.
How should time-temperature indicator records be organised for a retailer audit?
Records should be filed by production date and batch number in a format that allows rapid retrieval of all processing records for a specific batch — retort instrument records, indicator records, deviation records, and disposition decisions together. Many facilities maintain an electronic or physical batch production record folder that brings all processing documentation for a single batch together in one location. This makes responding to auditor requests for specific batch documentation straightforward and fast.
What is the required record retention period for canning process records?
Under FDA 21 CFR Part 113, canning process records must be retained for a minimum of three years. Under BRC Food Safety Issue 9, records must be retained for the shelf life of the product plus one year, with a minimum of two years. For products with long shelf lives (two to five years), BRC records may need to be retained for up to six years. Your quality management system and customer contracts may specify longer retention periods. Clarify the applicable requirements with your HACCP consultant or quality manager.
What happens if a time-temperature indicator shows a process deviation during production?
Place the affected batch on quality hold immediately. Do not release the product to distribution. Initiate a deviation investigation to determine the cause: check the retort instrument records for the same run to identify whether the retort itself operated within the scheduled process parameters. Consult your Process Authority for guidance on the disposition of the affected product. The disposition options typically include destruction, re-processing (if technically feasible for the product type), or incubation testing followed by release if the investigation supports this. Document the deviation, the investigation, and the disposition decision in full, and update your deviation records accordingly.
Can we use electronic data loggers instead of time-temperature indicators for production monitoring?
Yes — electronic data loggers placed inside the retort load can serve a similar function to time-temperature indicators for production monitoring, and have the advantage of providing time-resolved temperature data. However, they are more expensive, require periodic calibration and battery replacement, and generate data that requires retrieval and analysis rather than immediate visual reading. For high-volume production facilities, time-temperature indicators offer a practical and cost-effective alternative for the routine per-batch check function, with electronic loggers used for process validation work and periodic performance verification.
About Temperature Indicators Ltd
Temperature Indicators Ltd is a specialist global distributor solely focused on temperature-sensitive labels, tags, and indicators for cold chain monitoring, process validation, and regulatory compliance. With 35 years of experience and operations shipping to over 50 countries worldwide, we supply food manufacturers, pharmaceutical distributors, sterile services departments, and logistics providers with the temperature monitoring solutions they need to maintain compliance. Contact us for expert guidance on temperature monitoring for your application.
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The information provided in this article is for general guidance only. Temperature Indicators Ltd makes no warranties, express or implied, regarding the accuracy or completeness of this content. Product specifications, regulatory requirements, and industry standards may change over time. Always verify current requirements with the relevant regulatory authority and consult a qualified professional before making decisions based on information contained in this article. Temperature Indicators Ltd accepts no liability for actions taken in reliance on information provided here.
- Temperature Indicators Staff
