Laboratory Analysis and Product Testing

Purpose and limits

Laboratory testing can verify composition, identity, contaminants, microorganisms, residues, pH, water activity, salt, curing agents and process outcomes. It answers the question defined by the sample and method. It cannot by itself prove that every unit in a batch is safe or that the process remained controlled. Testing complements preventive process controls and documented production evidence.

Decision question and specification

Before sampling, define the measurand, matrix, unit, decision limit, regulatory or internal basis and consequence of the result. Screening, release, investigation and legal enforcement may require different methods. A test for total salt is not a nitrite assay; species screening is not necessarily quantification. The laboratory should confirm that its method fits the intended decision.

Sampling plan

The sample plan identifies lot, selection method, number of units, locations, increments, composite rules and retained samples. Cured products can vary by surface, centre, piece, rack and process time. A precise result from a biased sample remains biased. Random, stratified, targeted and worst-case samples serve different purposes and should not be presented as equivalent.

Sample collection and custody

Collection tools, containers, quantity, temperature, preservation and transport should protect the analyte without contamination or change. Labels and chain of custody link the physical sample to batch, location and time. Subsampling and homogenisation in the laboratory can materially affect result. Samples received warm, leaking, unidentified or insufficient require documented qualification or rejection.

Method selection and validation

A method should specify matrix, analyte, principle, range, detection or quantitation limits, precision, bias, interference and quality controls. Official or published status is helpful but does not guarantee fitness for a changed matrix. Modifications may require verification or revalidation. Rapid instruments and kits should be compared with an appropriate reference method for the actual product.

Laboratory competence and scope

ISO/IEC 17025 addresses competence, impartiality and consistent laboratory operation. Accreditation applies to a defined scope listing activities, methods or capabilities; it is not a blanket endorsement of every test on a price list. The client should review the current scope, subcontracting, reporting, proficiency performance and method version relevant to the decision.

Calibration and quality control

Analytical runs use reference materials, blanks, duplicates, spikes, calibration checks, positive and negative controls or other method-specific evidence. These controls show whether the run performed within acceptance criteria. Instrument calibration alone cannot correct sample bias or matrix interference. Failed controls invalidate or qualify results according to the controlled laboratory procedure.

Detection, quantitation and uncertainty

Detected, not detected, below quantitation and measured concentration are different statements. Reporting limits and measurement uncertainty affect interpretation near a specification. Extra displayed digits do not create evidence. Decision rules should state how uncertainty, recovery and rounding are treated. A borderline result may require repeat analysis or additional representative samples rather than automatic acceptance.

Microbiological results

Microorganisms are often unevenly distributed, and absence in a tested portion is not proof of absence from the lot. Enumeration and presence-absence methods answer different questions. Sampling unit, enrichment, compositing, stressed cells, transport and laboratory controls affect interpretation. Trend and process data may be more informative than a single negative finished-product result.

Composition and authenticity

Moisture, fat, protein, salt, curing agents and species identity support formulation, label, legal and fraud controls. Results depend on method basis and sample preparation. Calculated formulation values, rapid screening and reference chemistry should remain distinguishable. Species DNA can identify biological origin but does not necessarily quantify meat content without a validated quantitative method.

Out-of-specification investigation

An unexpected result triggers preservation of the original data and sample, review of custody, method controls, calculations, instrument status and production history. Retesting should follow a predefined rule and must not become repeated testing until a passing value appears. The investigation should distinguish laboratory error, sample non-representativeness and genuine product or process failure.

Records and data integrity

Reports should identify sample, method, version, result, unit, qualifiers, reporting limit, uncertainty where relevant and laboratory status. Raw data, calculations, changes and approvals require retention. Electronic systems should preserve auditability. Results should link to product hold, disposition and corrective action. Transcribing only the final value into a batch record loses essential context.

Testing within process control

Testing frequency and location should be risk based and connected to the process. Online or rapid measurements can support immediate adjustment; external laboratory tests may verify longer-term performance. Neither route replaces validated recipes, sanitation, temperature, fermentation or drying controls. The strongest system uses test results to confirm and improve a controlled process rather than inspect safety into finished product.

Internal versus external laboratories

An internal laboratory can provide rapid process feedback but requires controlled methods, trained staff, equipment, quality controls and independence proportionate to the decision. External laboratories add specialist capability but also transport, custody and reporting delay. The sampling owner and decision authority remain with the food business. Contract terms should define method, turnaround, urgent notification, subcontracting, sample retention and data access.

Trend analysis and control charts

Single results answer a batch question; trends can reveal gradual change in salt, moisture, pH, yield, environmental counts or equipment performance. Trending requires comparable methods, sampling locations and units. A shifted method or product mix should be annotated rather than blended blindly. Alert and action limits should distinguish normal process variation from a signal requiring investigation before formal specification failure occurs.

Legal and evidential use. Results used for label, regulatory, supplier or dispute decisions need stronger control of custody, method status, calculations, uncertainty and authorised reporting. The original report and raw-data availability should be preserved. An informal in-house screening value may justify a hold but not necessarily a legal conclusion. Escalation rules should identify when confirmation by an appropriately competent laboratory is required.

Sample retention and confirmatory work

Retention quantity, storage condition and duration should permit confirmatory analysis without allowing the sample to change materially. Freeze-thaw, moisture loss, oxidation and microbial growth can make a retained portion non-equivalent to the original. When confirmation is required, the plan should specify whether the same homogenate, a retained unit or new independent samples answer the decision, and should preserve the original result rather than overwrite it.