The growing risk of UK food fraud during the COVID-19

# The growing risk of UK food fraud during the COVID-19

The COVID-19 pandemic raised UK food fraud risk by disrupting supply chains and weakening inspections. Cheap oils, substituted species, and diluted ingredients entered retail and catering channels. This article gives a practical testing framework: fraud pressures during the pandemic, sample selection and collection, ELISA and PCR authenticity methods, HPLC–MS screening, sensitivity and specificity, and testing panels anchored to UK and EU standards.

UK food fraud risks under COVID-19

Pandemic conditions weakened several controls that normally deter adulteration. Local authority inspection capacity fell as staff were redeployed. Remote audits replaced physical site visits in many supply relationships. At the same time, price volatility made substitution profitable. Olive oil, honey, herbs, spices, and fish species have long attracted fraud, and pandemic cost pressure intensified that incentive. Imported ingredients passing through overburdened logistics hubs carried greater traceability gaps. Relabelling of near-expiry stock also rose in retail settings.

For buyers and quality managers, the practical response is risk-based verification testing rather than blanket screening. Category risk, supplier history, and price anomalies should drive sampling frequency. This concentrates limited analytical budgets on the points in the chain where substitution is most probable and most damaging.

Sample types and collection

Fraud verification begins with representative sampling across the suspect matrix range: raw meats and fish, processed and comminuted products, oils and fats, dairy, honey, spices, and herbal materials. Each matrix dictates its own handling. Muscle tissue for species testing should be sampled away from processed surfaces where cross-contamination is likely. Oils require clean, sealed containers with minimal headspace to limit oxidation before analysis. Honey and spice samples must be homogenised thoroughly because adulterants often distribute unevenly.

Chain-of-custody documentation is decisive when results may feed into supplier action or regulatory notification. Record batch codes, dates, storage conditions, and sealed tamper-evident packaging for every sample. Sampling plans should follow recognised statistical principles, weighted toward higher-risk batches. Any sensory notes recorded at collection, such as unexpected colour or odour, can later guide method selection. This connects field observation to laboratory analysis rather than leaving the two stages disconnected.

Authenticity testing by ELISA and PCR

Two complementary technologies carry most authenticity work. ELISA detects species-specific proteins using antibody binding. It suits routine, high-throughput screening of raw or mildly processed meats: an extract is immobilised, incubated with enzyme-linked antibodies, and read colorimetrically by spectrophotometry. It is fast and inexpensive. However, protein denaturation during heat treatment can reduce antibody binding, which limits its use in cooked or sterilised goods.

PCR, particularly real-time PCR and DNA barcoding, targets species-specific gene sequences. It remains reliable after processing because DNA survives heating better than epitopes. DNA extracted from the sample is amplified with primers flanking a discriminatory region. The amplicon pattern or melt profile identifies the species present, and quantitative variants estimate substitution proportions.

In practice, ELISA serves as a first-line screen across many samples. PCR confirms positives and resolves mixed or highly processed products where immunoassays lose resolution.

Species

and adulterant screening by HPLC–MS
Where the question is chemical rather than biological — what a product contains, not which animal it came from — HPLC–MS provides the core platform. It couples liquid chromatography with mass spectrometric detection. This separates compounds by retention time and confirms identity by mass-to-charge ratio and fragmentation pattern. Typical fraud applications include detecting undeclared colourants in spices, synthetic adulterants in honey, non-declared plant oils in olive oil via triglyceride and fatty-acid profiling, and migration of unauthorised substances from packaging into food.

Sample preparation usually involves solvent extraction, filtration, and, where required, clean-up before injection onto a reversed-phase column. GC-MS complements this for volatile markers such as fragrance or solvent residues. Interpretation relies on comparing mass spectra and retention behaviour against reference standards or validated spectral libraries. Because HPLC–MS can screen many analytes in a single run, it suits surveillance programmes testing broad adulterant panels across a supplier base rather than one suspect compound at a time.

Assay sensitivity and specificity

Method performance determines whether a result can support commercial or regulatory decisions. Sensitivity, usually expressed as a limit of detection, defines the lowest adulterant proportion the assay can distinguish from background. This is critical when substitution may occur at low percentages deliberately chosen to evade visual checks. Specificity defines whether the assay responds only to the target species or compound, avoiding false positives from closely related species or structurally similar molecules.

Cross-reactivity is a known weakness of antibody-based assays and must be documented for each matrix. Validation should therefore confirm performance in the actual food matrix, not only in the reference material. Processing, fat content, and matrix interference all shift detection limits. Laboratories running fraud programmes typically report detection capability alongside qualitative presence/absence calls. Buyers can then judge whether an assay would catch the substitution level of concern. Where two methods disagree, the more specific technique, usually DNA- or MS-based, takes precedence in confirmatory reporting.

Testing panels and regulatory standards

Fraud testing delivers most value when organised into defined panels rather than ad hoc requests. A typical panel for a meat product chain covers major species plus common economic substitutes. An oil panel covers fatty-acid and triglyceride markers. A honey panel covers added-sugar markers such as foreign oligosaccharides.

Results are interpreted against UK food law retaining EU framework Regulation 178/2002 on food safety, EU marketing standards where applicable, and UK-specific labelling requirements. Authenticity criteria come from recognised reference methods and standardised analytical protocols. Accredited laboratories operating to international laboratory competence standards give results the standing needed for supplier disputes or enforcement referral.

Documentary checks should accompany analysis: verified traceability records, import documentation, and labelling review together close gaps that chemical testing alone cannot see. Combining targeted analytical panels with document verification and periodic unannounced sampling gives the strongest defence against pandemic-era fraud pressure.