This e-book (purchase required) covers the most common non-destructive methods used in food quality and authenticity analysis, including machine vision, Spectroscopy, E-nose/tongue, Ultrasonics, and hyperspectral imaging.. While these methods have been in practice for some time, the technological advancements of the last decade have improved the precision and reliability of these tools, making them more popular. 

The book intends to be a research volume giving an overview of the dominant non-destructive methods, including the more novel technologies such as biosensors and terahertz application.  It brings together detailed information on all these most current advances in technology and elucidates their application in food processing. It covers theory, principle, recent advances and practical applications in food analysis.  The book is aimed at students, researchers, food trainers and industry personnel.

The chapters all focus on applications in food analysis

• Spectrtoscopy: Optical Methods. Visible, NIR, FTIR
• NMR
• Computer vision systems
• X-Ray, CT and MRI
• Hyperspectral imaging
• Multispectral imaging
• Backscattering imaging
• Biospeckly imaging
• Thermal imaging
• Terahertz spectroscopy
• Ultrasonics
• Electronic nose and electronic tongue
• Biosensors
• Techniques based on electrical properties of food
• Colour and texture measurements
• AI and Machine Learning
• Back matter

In this proof of concept study (open access) the authors used machine learning to build a classification model for saffrom authentication using mid infrared spectroscopy (MIR).  MIR is a portable technique.

111 authentic saffron samples (2023 harvest) were directly sourced from farmers in 6 different regions of Iran.

 Adulterant were prepared in-house by blending 1 – 30% of saffron style, safflower, madder, or calendula.

After grinding  into a uniform powder and then sieved in accordance with ISO 3632 standard, the samples were washed, dried, ground and then extracted into ultrapure water.  Extracts were filtered, then analysed by a solvent MIR spectrometer.

The authors report that data-driven soft independent modeling of class analogy (DD-SIMCA) successfully differentiated between authentic and adulterated samples, achieving 100 % sensitivity and specificity. PLS-DA and RSDE were then employed to identify the type and level of adulterants, with RSDE clearly outperforming PLS-DA, achieving accuracy above 94.0 %, as compared to PLS-DA's accuracy of over 90.0 %. They were also able to differentiate between the 6 Iranian growing regions. The authors do not report if they challenged or validated their model with samples independent of the reference set.

In conclusion, they conclude that the combination of solvent-based MIR spectroscopy and modern chemometric techniques shows great potential as a reliable tool for saffron quality control at the point of need.

Photo by Vera De on Unsplash

The canning process has a degrading effect on DNA, making the species verification of canned tuna more challenging than for raw fish.

In this paper (open access) the authors optimised and compared three PCR approaches: real-time PCR (RT-PCR), mitochondrial control region (CR) mini-barcode, and multiplex PCR.  They tested 24 samples labelled as either albacore, yellowfin, skipjack or light tuna.

They reported RT-PCR as having the highest identification rate (100%), followed by CR mini-barcoding (33%) and multiplex PCR (29%). They consider that the success of RT-PCR may have been due to the short (<100 bp) DNA fragments targeted. In comparison, multiplex PCR and CR mini-barcoding targeted slightly longer fragments of 127–270 and∼236 base pairs, respectively. Regarding species identification, CR mini-barcoding and multiplex PCR confirmed the presence of albacoreor yellowfin tuna in several samples; however, both methods struggled with the identification of skipjack tuna.

CR mini-barcoding enabled sequencing-based detection of a range of species in the products. The authors conclude that a combination of real-time PCR and CR mini-barcoding is the optimum approach for rapid screening of target species along with sequencing-based confirmation.

Photo by Grooveland Designs on Unsplash

Adulteration of Halloumi cheese using skim milk powder is a known risk in Cyprus.  The fraudsters adjust the composition to comply with PDO specifications for moisture, fat and salt content.

In this paper (open access) the authors prepared reference samples of authentic Halloumi (from a local artisan producer) and their own “PDO-specification” adulterated samples with 1% and 5% skim milk powder inclusion

They tested these reference samples using Brunauer–Emmett–Teller (BET) – a measurement of the specific surface area - and Fourier-Transform Infra-Red Spectroscopy (FT-IR).  Principal component analysis (PCA) was employed to visualize and interpret the spectral data. The specific surface area from BET measurements and the FTIR spectral subregion between 1650 and 1100 cm⁻¹ were key factors, and they were retained for model construction.

The authors plan to build on these initial results by including a wider range of milks and cheeses in the model, and by model validation.  They have published at this early stage because they believe this is the first time BET has been applied or shown promise in contributing to such a multi-variate classification model.

This article (purchase required) uses data mining of nearly 72,000 official food inspections from China from 2018 – 2023.  It tests the hypothesis that data manipulation by local food inspection agencies has led to an overall underestimate of food fraud and food safety incidents in China.

The authors examined the distribution of non-compliant samples near the qualified standard value using exceedance multiples. To quantify the extent of data manipulation, they used an exhaustive algorithm to construct counterfactual estimates.

They report an abnormal distribution of unqualified samples near standard value, indicating potential data manipulation. Robustness tests supported this inference.

They conclude that over 11% of unqualified (failed) samples may have been adjusted to qualified status during 2018–2023, with higher manipulation rates in eastern regions than in central and western regions. The manipulation rate of unqualified samples across 25 sample provinces ranged from 8.13% to 16.30%.

Yohimbine is a prohibited or restricted ingredient in food supplements in many regulatory markets, including the EU and UK.  It is believed to be an aphrodisiac.  Yohimbine (either undeclared or labelled) has accounted for a disproportionate number of regulatory seizures and supplement recalls over the past few years. There can be a food safety risk.

In this study (purchase required) the authors developed and novel binding assay for yohimbine, and worked it up to proof of concept in a rapid test kit (lateral flow device).

The authors used computational-chemistry-based prediction to design haptens to then generate a high-affinity monoclonal yohimbine antibody Yohi-4A7.  They then used this antibody to construct a gold nanoparticle-labelled immunochromatographic assay (ICA).

They report that the ICA presented cut off values of 5.0 ng/mL for aphrodisiac liquor and 5.0 ng/g for capsules, with detection limits of 0.56 ng/mL and 0.88 ng/g, quantification limits of 1.96 ng/mL and 2.58 ng/g, and satisfactory accuracy reflected by recovery rates ranging from 96.0 to 120.7%, respectively. Analysis of 26 blind samples using the ICA, followed by comparison with liquid chromatography–tandem mass spectrometry results, revealed strong concordance between the two techniques

This article (open access) is an early publication of a paper that has been through peer review but not yet through journal typographical editing.

During 2019-2021, a total of 78 samples of fish products from national and international brands were.collected from supermarkets, fishmongers, and other local retail stores in the Apulia region (Southern Italy).  They were tested using PCR and DNA barcoding.

The authors report that 5 of the 78 samples were fraudulently labelled.

They also discuss the role of DNA barcoding, challenges with processed fish products, and the pros and cons of different public databases (BOLD and BLAST).

Photo by Marko Markovic on Unsplash

This review (open access) analyses trends in reported food fraud incidents over the past 5 years and trends in detection technologies, particularly the integration of AI and digital traceability and detection systems with analytical testing.  The authors base their analysis on the EC Joint Research Centre monthly collation of food fraud media reports.

The authors highlight that food fraud is a worldwide issue, but its incidence is unevenly distributed across countries. A few countries account for a disproportionate share of reported cases. Notably, Italy has the highest number of food fraud incidents, with over 300 cases. India, and Pakistan also rank in the highest quintile, each reporting well over 150 cases. These three countries alone represent the upper 20 % bracket of fraud occurrence globally. A second tier of countries, including Spain, Brazil, Bolivia, Malaysia, Colombia, and Argentina, report a few dozen cases each.  This skewed distribution suggests that detections of food fraud are concentrated where high-risk products, and active enforcement intersect.

The authors conclude that igrating AI-based predictive analytics with traditional and emerging lab methods significantly improves fraud detection, while blockchain and Internet of Things (IoT) innovations enable secure, real-time tracking of food authenticity. These technologies collectively strengthen the ability to uncover fraud

The paper emphasizes the need for interdisciplinary collaboration, harmonization, and updated regulatory frameworks to support the adoption of these multi-disciplinary approaches.

The EC Monthly Reports of Agri-Food Fraud Suspicions reports are a useful tool for estimating fraud incidents, signposted on FAN’s Reports page.  They can be found here.

FAN produces rolling 3-month graphical analysis. In order to show consistent trends we have excluded cases which appear to be unauthorised sale but no intent to mislead consumers of the content/ingredients of a food pack (e.g. unapproved food additives, novel foods), we have excluded unauthorised health claims on supplements, and we have excluded residues and contaminants above legal limits.  We have grouped the remaining incidents into crude categories.  Our analysis is subjective, intended only to give a high-level overview. 

One clear signal in July is the (unwelcome) return of undeclared dyes and colours - the large purple bubble top-centre of the chart.  3 of these cases are Sudan dyes in spices, an issue that has been bubbling for over 20 years.  But 3 are relatively new - green dye in pistachio paste, which is linked to the current regulatory watch-out of Dubai chocolate.

Our main takeaway message continues to be that industry risk-assessment too often focusses on specific ingredients as "high risk".  In actual fact, it is the TYPE of fraud that is consistent; falsification of traceability or health documents/certification, illegal import, bulking out more expensive ingredients with cheaper ones.  The affected ingredients or products vary.  This suggests that risk assessment should focus more on motivation and opportunity in the supply chain, and less on "counting RASFFs".

The EC Monthly reports are only one source of information.  A comparison of the many different information sources now available is given in an earlier blog this week.

The UK Parliamentary Committee on Environment Food and Rural Affairs published their latest report on border checks of imported meat earlier this month.  The report is driven by biosecurity and disease control concerns but is also relevant to illegal food trade.

The Committee is critical of the organisation and effectiveness of biosecurity checks currently in place in UK ports, and of a lack of central co-ordination.

They report that responsibility for tackling illegal meat imports is divided across Government departments, enforcement agencies and local authorities. They found no strategic approach coordinating efforts and no leadership figure spearheading operations. This has been the case under successive governments. 

The committee's view is that the stated UK approach of “intelligence led checks” obscures the reality on the ground: a limited and incomplete intelligence network, strained enforcement capability, and port facilities unsuitable for seizing significant volumes of potentially contaminated meat

It is the Committee’s view that the UK has avoided recent disease outbreak from illegally imported meat by luck rather than design.

This study (open access) tested 119 commercial products of insect flour, composite food and animal feed using two DNA-based methods, real-time PCR and metabarcoding, to check whether the insects claimed on the packaging were actually present.

The headline result is that 50% of the products contained insect species not listed on the label, or lacked the species that were declared. The detailed results are explained within the article and there are not always clear-cut interpretations (particularly for feed, where – for example -  it is not illegal to fail to declare all protein species within a pet food recipe).  However, some trends were clear.

• Many producers are unspecific about species identification, using general terms such as “cricket” which do not differentiate between legal and non-legal species
• Cross-contamination between different insect species is endemic
• Regulatory test methods (PCR) are not fit to tell whether the banned practice of rearing insects on substrate containing meat/bone has been used (because the method will also detect, for example, permitted animal-derived substrates such as egg shell)

The authors conclude that traceability and cross-contamination control needs to be improved in this nascent industry, before insects become mainstream, to avoid loss of public trust.

It is notoriously difficult to collate fraud incidents in order to track trends and prioritise generic risks by either food commodity or country.  One of the more useful free tools for the past 10 years has been the monthly EU Joint Research Centre (JRC) collation of fraud media reports.

The JRC have just launched a searchable front-end for their database of reports.  It allows filtering by commodity, country, fraud type and other key criteria.

The JRC collation is just one of the incident databases available.  It must be remembered that different databases collect different information, in different ways, and therefore show a different angle on the true picture.  All of these sources are signposted on FAN.  Best practice is to use a combination of all sources, but the final critical question is “how vulnerable is my own supplier”.

• JRC – These are solely media reports.  They exclude cases not in the public domain, and can be biased by shocking but highly localised incidents in local food supply within poorly regulated countries.  For the past few years, FAN member Bruno Sechet has produced a useful infographic based on each month's data
• EU Agri-Food Suspicions – These are solely EU Official Reports, and only suspicions.  The root cause of each incident is unknown.  The data include pesticide residues above their MRLs.  FAN produce our own infographic on a rolling 3-month basis.
• Food Industry Intelligence Network Fiin SME Hub – These are aggregated anonymised results from the testing programmes of large (mainly UK) food companies.  The testing programmes are targeted and risk-based, not randomised, and the fraud risks within the suppliers of large BRC-certified retailers and manufacturers may be different than the companies supplying small manufacturing businesses or hospitality firms

Many testing laboratories also supply their own customers with incident collations, and there are many commercial software systems that scrape reports from the internet.  All collect and treat the data slightly differently.  FAN produce a free annual aggregate of "most adulterated foods" from three of the commercial providers, which gives very high level smoothed data.

This report from Coalition for Fisheries Transparency members the Environmental Justice Foundation and Open Seas finds that UK consumers may unknowingly be buying seafood linked to illegal, unreported and unregulated (IUU) fishing and human rights abuses.  The report highlights that the frequency with which catch certificates are checked has fallen dramatically following the UK’s exit from the EU.  It points to the high volume of UK imports originating from countries which are seen as high risk of IUU fishing and catch traceability fraud, including consignments likely to be Russian catches routed via 3^rd countries in order to avoid sanctions.

The undeclared forced (chemical) ripening of fruits usually is not seen as a high fraud risk by large retailers with systematic supply chains.  It is a much higher risk in domestic supply to local markets in the countries where the fruits are grown.  In some cases, illegal use of ripening chemicals can put consumers at risk.

The Nigerian federal government sees the issue as a high priority has vowed to sanction those involved in food adulteration and forced fruits ripening in markets. They have run recent regional one-day sensitisation programmes on Forced Ripening of Fruits, Adulterated Palm Oil, Contaminated Meat and Grains.

Media coverage of one of the regional education events can be found here.

The authors of this study (purchase required) propose a radio frequency (RF)-based sensing method that operates in the 6.22 GHz frequency range as a method to authenticate edible oils. In order to obtain a return loss below -10 dB within the desired frequency range, their sensor makes use of a microstrip patch antenna with triangular slots and a microfluidic channel that has been adapted by parametric variations.

They tested the concept with in-house preparations of olive oil which were then adulterated with increasing quantities of coconut and mustard oils.  Results were correlated with GC-MS.  They report that the sensor's measured sensitivity for identifying oil adulteration is 0.18, and conclude that this demonstrates proof of concept for using an RF sensor as a quick method of verifying vegetable edible oils.

In this study (open access) the researchers proposes using a MALDI-ToF and LC-Q-ToF dual approach, following trypsin digestion, as a method to verify fish species.  Trypsin digestion breaks the proteins down into peptides, and they used peptide fingerprints to identify peptides that were unique markers for specific species. The advantage of their approach over DNA methods, and in comparison to MALDI-ToF-MS analysis of undigested proteins, is that it can be applied to complex and heat-processed samples.

The study aimed to differentiate six fish species—carp, mackerel, pike, pollock, salmon and trout. Matrix-assisted laser desorption/ionization–time ff flight mass spectrometry (MALDI-TOF MS) was employed to identify characteristic species-specific m/z values to differentiate raw and cooked fish meat. Additionally, liquid chromatography–electrospray ionization–quadrupole–time tf flight (LC-ESI-Q-TOF) was used to determine specific amino acid sequences in carp and salmon, selected as model species.

Two or more distinct species-specific m/z markers were identified for all six fish species, enabling their differentiation in both raw and processed form. A slightly larger list of distinct markers were found for cooked, compared to raw, fish.  In carp and salmon, hundreds of peptide sequences were detected, leading to the identification of a panel of peptide markers that determine both the fish species and the type of meat processing. The results confirm that mass spectrometry-based proteomic approaches can serve as effective tools for the authentication of fish meat.

The authors conclude that it is possible to use two complementary mass spectrometry techniques for reliable and rapid authentication of fish species. By focusing on peptide-level markers and leveraging accessible tools, they believe that the approach offers a cost-effective and innovative alternative for fish meat authentication.

Isothermal amplification techniques offer an alternative to “classical” PCR and are more suitable to point-of-use technology.  For a general overview, see FAN’s analytical method explainers.  Recent advances have enabled the development of microfluidic chip platforms, which integrate micro-scale channels, pumps, chambers, valves, and sensors onto a single substrate for fluidic control. This integration enables simultaneous sample pretreatment, component separation, detection, and biochemical analysis on a single platform.

Recombinase polymerase amplification (RPA) is an isothermal method that has gained attention due to its low instrument dependency, high sensitivity, and rapidity. RPA reactions can be conducted at near-ambient temperatures (37–42 °C) within 20 minutes, and results can be interpreted via fluorescence signals or lateral flow dipstick by incorporating sequence-species probes. The exo probe, typically 46–52 nucleotides in length, is widely used in real-time RPA detection. The design of primers and exo probes in RPA assays offers potential for seamless integration with microfluidic chip platforms.

In this study (purchase required) the researchers integrated RPA into a microfluidic chip to develop an assay for identifying commonly marketed codfish species prone to adulteration: Atlantic cod (G. morhua), sablefish (A. fimbria) and toothfish (D. eleginoides and D. mawsoni).

They reported that the assay demonstrated high specificity and sensitivity, with detection limits of 10 copies/μL recombinant plasmid or 10³ fg/μL genomic DNA. Application to 141 commercial seafood products resulted in 100 % identification accuracy for the three target species, and revealed a 32 % inconsistency between product labels and genetic identities, involving substitutions with Pacific cod, pollock, and other species.

They conclude that on-chip RPA assay offers a rapid, high-throughput, and reliable tool for seafood authentication and potential mislabeling surveillance.

Photo by Patrick Boucher on Unsplash

In this recorded conversation (open access), Karen Constable (Director, Authentic Food) and John Points (Technical Director, FAN) discuss the role of analysis in a modern fraud prevention strategy. 

Our conversation ranges across topics integral to FAN including:

• tools in the toolkit of food fraud prevention and mitigation best practice
• when and where to use testing within that toolkit,
• how to select a test that is fit for purpose,
• how to find a laboratory that can meet your needs,
• how to interpret the significance of results
• what action to take on "suspicious" results. 

The discussion is particularly focussed on free or low-cost resources that are of practical use to Small and Medium Enterprises in the food sector, and practical steps that SMEs can take to reduce the chance of falling victim to fraud.  We signpost lots of resources that are freely available, including the new Food Industry Intelligence Network's SME Hub.

Detecting the mislabelling of thawed meat as fresh meat has been an analytical challenge for many years.  The most established technique, based on measuring the HADH enzyme (see FAN method explainers) is not perfect.

This paper (purchase requires) reports the development of an assay based on a different biochemical marker enzyme for the detection of previously-frozen pork The authors proposed mitochondrial citrate synthase (CS) as a candidate biomarker enzyme, and developed an ELISA to measure CS and test their hypothesis.

For the development of sandwich ELISA, polyclonal antibodies (pAb) against CS were produced in two different laboratory animals (rabbits and guinea pigs). A sandwich ELISA was optimized by utilizing rabbit anti-CS pAb as capture and guinea pig anti-CS pAb as detection antibody,  The limit of detection (LOD) and limit of quantification (LOQ) of the sandwich ELISA were calculated to be 3.71 ng/ml and 11.24 ng/ml, respectively. The sandwich ELISA was having 100.78 ± 1.66 % of accuracy, and the assay was found to be having good repeatability as well as reproducibility. The assay showed a good storage stability up to 12 weeks of storage at refrigeration temperature (4 ± 1 °C).

The authors report that there was a statistically significant difference between results from fresh/chilled and frozen/thawed pork meat.

Photo by patrick le on Unsplash

Cold-pressed fruit seed oils from blackcurrant, raspberry, and strawberry are gaining market share and – as relatively high value oils – are potential targets for adulteration. This study (open access) used identified 28 triacylglycerides (TAGs) as significant markers for distinguishing the 3 oils.  These were identified from chemometric analysis of full tryglyceride profiles.  Triglycerides were measured by ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. Lipidomic analysis identified 215 glycerides in the three oils. Chemometric analysis revealed that TAG profiles were superior to diacetylglyceride (DAG) profiles for oil differentiation and detecting adulteration. OPLS-DA identified 28 TAGs as significant markers for distinguishing the three oils.

The authors reported that comparison of glyceride profiles of pure and adulterated samples demonstrated that adulteration with 5 % or more sunflower or rapeseed oil could be detected. Targeted metabolomic analysis using specific markers for sunflower oil confirmed adulteration in raspberry and strawberry commercially purchased fruit seed oils.

Photo by Stan Slade on Unsplash