Authenticity has been a major concern of consumers, producers, and regulators since ancient times. By definition, to be authentic is to be genuine or of undisputed origin and not a copy. Similarly, food authenticity is the quality of food to be genuine and undisputed in its nature, origin, identity and claims, and to meet expected characteristics including safety, quality and nutrition. Food authentication is the process that verifies that food is in compliance with its label description. This may include, among others, the origin (species, geographical or genetic), production method (conventional, organic, traditional procedures, free range), or processing technologies (irradiation, freezing, microwave heating). The declaration of specific quality attributes in high-value products is of particular interest since these products are often the target of fraudulent labelling. Proof of provenance is an important topic for food safety, food quality, and consumer protection, as well as compliance with national legislation, international standards, and guidelines. Due to the globalization of food markets and the resulting increase in variability and availability of food products from other countries, consumers are increasingly interested in knowing the country of origin along with the assumed quality of the products they eat and drink. The quality assurance and the methods used to authenticate foodstuffs are of great interest both from commercial and legal points of view.
Modern instrumentation, advances in basic sciences and in information and communication technologies provide means for precise measurement and elucidation of the origin of foods. The production of consumer goods according to these standardized procedures normally results in better products and is rewarded with higher prices at the point of sale.
Determination of food authenticity is an important issue in quality control and food safety. Authenticity testing is a quality criterion for food and food ingredients, increasingly a result of the legislative protection of regional foods. Thus, there is a pressing need for accurate standardized food authentication techniques. Food authenticity testing does not serve only consumers; the stakeholders include food industries that are seeking the opportunity to assure their food products labelling compliance and branding. Regulatory authorities are asking for an extended and updated list of analytical methods to confirm authentic food products and support law enforcement. In response to these and other events, standard requirements are being set up around the world. One example is the British Retail Consortium Global Standards (BRCGS), a leading brand and consumer protection organization used by over 26,000 certificated suppliers in over 130 countries. BRC Version 8 includes standards to protect food authenticity and to prevent/reduce food fraud by 1) having access to information on historical and developing threats to the supply chain, which may present a risk of food fraud, 2) performing a documented vulnerability assessment on all food raw materials, and 3) performing appropriate assurance and/or testing to reduce uncovered risks for raw materials.
Importance of Authentication
Typical examples are:
- Wine authenticity –illegal sugar addition to grape juice
- Addition of sugar to honey
- Addition of hazelnut oil to olive oils
- Mislabelling geographical origin (wine, olive oil)
- Mislabelling organic food products
- Adulteration of meat with cheaper species (beef burger patties with horse meat)
- Dairy products containing nitrogen-enhancing melamine/cyanuric acid found in infant formula and pet foods, resulting in illnesses and deaths.
- In a 2018 audit, almost half of 382 samples of marketed fish were not what the label indicated them to be (Ruryk and Chung 2018).
Authenticity tests for products and product properties
Authenticity testing is the analytical authenticity verification of food and feed with regard to its composition, purity, origin, and production. A distinction is made between targeted and non-target (profiling/fingerprinting) methods.
Using targeted methods, the food or feed sample is examined for a very specific adulteration which will either be confirmed or refuted.
In the case of non-targeted methods, the entire profile or specific characteristics of a food or feed sample are determined as a so-called physical-chemical or molecular fingerprint which will be compared with other reference data from a previously created database. If the new profile image matches the reference profile stored in the database, the sample is authentic.
Analytical techniques for Food Authenticity- Molecular Techniques, Genomics – Proteomic
A variety of analytical techniques, for verification of foodstuff origin have been developed and tested. Molecular analysis for discrimination of original (authentic) food products from non-original is a major authentication methodology. Even though traditional methods have been extensively used for food authentication, genomic and proteomic techniques are rapidly complementing or outright replacing earlier methods. Nucleotide- and protein-based methods for food authentication are mostly used for species detection and identification. Since DNA is identical in all somatic cells of a given organism, it is invariant whether the DNA is extracted from blood, muscle, liver or any other tissue. High stability of DNA allows the analysis of highly processed food products, as well as trace contaminants. DNA-based methods for food authentication depend on the highly specific amplification of DNA fragments by the Polymerase Chain Reaction (PCR). This method belongs to “genomics”, because the whole genome of the sample is used. On the other hand, proteins can act as markers for many properties of the food products all along the food chain from farm to fork, and therefore proteomics can be applied for a systematic search of new marker proteins or peptides. The advantage of genomics is that it can amplify minute traces of nucleotide material, while proteomics identifies specific products encoded by DNA. The sensitivity of these methods is very high since the amount of required material can be as small as a few cells. After the first discovery step using reference samples, reliable analytical methodologies are needed for targeted detection and quantification of characterized markers in real unknown samples. These proteogenomic techniques are constantly being improved, examples include PCR Single Strand Conformation Polymorphisms, (PCR-SSCP), random amplified polymorphic DNA (RAPD), or the emerging field of Peptide Nucleic Acid (PNA), and DNA fingerprinting that are used for food authentication. Genomics and proteomics are usually applied to identify false descriptions and mislabelling of foods. Interesting examples are: the detection of GMOs, seafood authentication, authentication of kosher and halal meat, detection of horse meat and pork in food labelled as beef, game meat authentication, botanical origin of foods (olive oil, wine, tomato products, tea, and cocoa), species origin authentication (meat, milk, fish). Another emerging sub-field of proteogenomic is microbial fingerprinting for food authentication (Specific food products such as cheese, fruits, milk and dairy products, wine, cocoa, and organic foods.).
- Chromatographic Techniques
The chromatographic analysis provides rapid and reliable separation of chemically similar compounds in complex food matrices. In food authentication, chromatographic techniques must overcome several challenges inherent to food matrices. Food substrates consist of a great number of compounds, including peptides, lipids, carbohydrates, amino acids, fatty acids, organic acids, nucleic acids, phytochemicals, and other small molecules (additives, such as colorants, aromas, preservatives, and other exogenous compounds). These compounds are chemically diverse, ranging from small organic molecules (usually up to 1000 Da) to macromolecules (biopolymers), that can possess a wide range of polarities – some are apolar (like oils) while some others are strongly polar (like amino acids). Chromatographic methods produce unique chemical fingerprints that differentiate and authenticate foods. The authentication is based, on the identification of minimal analytical differences between patterns or the identification of unique marker compounds. Due to the chemical complexity of foodstuffs and high consumer demand for food quality and genuineness, high-resolution chromatographic techniques, such as gas (GC) or liquid chromatography (LC) coupled to mass spectrometry (MS), have emerged as useful food authentication tools. Double MS (triple quadrupole) is replacing older instruments and most instruments principally used are Gas Chromatography-Mass Spectrometry (GC-MS/MS), Liquid Chromatography Mass Spectrometry (LC-MS/MS), and Liquid Chromatography Time-of-Flight Mass Spectrometry (LC-TOF-MS). Authentication by chromatography is based on the profile of specific compound profiles for each food product, such as fatty acids, triglycerides, waxes, sterols, hydrocarbons, alcohols, tocopherols, and volatiles, which form profile characteristics for food identity origin. Examples, where chromatographic techniques are used for identifying the authenticity of foods, include adulteration of high-quality products with inexpensive or sub-standard ingredients such as honey, wines, vegetable and olive oils, spirits, coffee, milk, cheeses, saffron, nuts, and mushrooms. Such authentication is usually done by matching measured compound profiles with the pre-determined target values.
The analysis of isotopic ratios uses various methods such as Isotope Ratio Mass Spectrometry (IRMS), Multi Collector – Inductively Coupled Plasma – Mass Spectrometry (MC-ICP-MS), and Thermal Ionization Mass Spectrometry (TIMS).
The isotopic ratios are applicable to food authentication because stable isotope ratios change with the climatic conditions, geographical origin, soil pedology, and geology of the locations of food ingredients origin. As a primary indication, H and O isotopic data for organic matter in food are linked to the H and O isotope data of water from the source region which have geographical variability, N and C isotopes are related to the climate and the agricultural practices, and S isotopes are affected by geology, volcanism, distance from the sea, and certain anthropogenic effect.
It is used to detect adulteration of wine, honey, fruit juice, or maple syrup with cheaper extenders, such as water or sugar syrup made from maize or sugar cane. Other examples of isotopic ratio applications include the discrimination of natural vs. synthetic vanillin and the discrimination of champagne CO2 produced naturally by adding sugar to bottles from direct injection of industrial CO2. More recent applications of multi-isotope ratio analysis include geographical origin verification studies of wine, olive oil, orange fruit, honey, tomato, Chinese cabbage, meat, dairy products, eggs, seafood, and coffee. Furthermore, the isotopic fingerprinting can be combined with other indicators (e.g., elemental analysis, NMR, and GC) to improve the determination of the origin of a variety of food products.- Vibrational & Fluorescence Spectroscopy
Spectroscopy, in particular vibrational spectroscopy, is a fast and inexpensive method for both the assessment of food quality and food authenticity. Fluorescence spectroscopy is a simple, non-destructive, non-invasive and relatively inexpensive analytical technique. It features low to very low detection limits as compared to other spectroscopic techniques. Molecules detected by fluorescence spectroscopy are polyaromatic hydrocarbons and heterocycles with rigid molecular skeletons. Recently, simple accurate and low cost fluorometers combined with advanced analytical software allowed fast, reliable, repeatable measurements and elaboration of the spectra. Hence, many fluorometric methods have been developed to check the authenticity, adulteration, quality and composition of foods.
Characteristic examples of spectroscopic methodologies deployed for food authentication include milk and soya bean meal adulteration by melamine, honey adulteration by syrups (high fructose corn, maltose, or jaggery syrup) and sugar solutions, adulteration of olive oil by vegetable oils or lampante/pomace olive oils, ground black pepper mixing with buckwheat and millet, culinary spices adulteration by Sudan I dye, and meat adulteration. Authenticity identification of milk, olive oils, honeys, wines, spirits, spices and other food ingredients, saffron and lentil seeds have been reported.Elemental profiling is increasingly applied to the assessment of food authenticity. Elemental profile refers to macro-elements (such as sodium, calcium and potassium), trace elements (such as copper, zinc and selenium), rare earth elements (such as lanthanum, cerium and samarium), or other elements occurring only at very low abundance (such as iridium and gold). Plants derive their mineral content from the soil. Elemental profiling is increasingly applied to the assessment of food authenticity. Elemental profile refers to macro-elements (such as sodium, calcium and potassium), trace elements (such as copper, zinc and selenium), rare earth elements (such as lanthanum, cerium and samarium), or other elements occurring only at very low abundance (such as iridium and gold). Food authenticity applications of ICP-MS and ICP-AES include discrimination of geographical origin, organic vs conventional products, and free range vs. cage egg production. Other examples of elemental fingerprinting analysis of food authenticity are the discrimination of origin of wine, honey, olive oil, coffee, cheese, fruits and vegetables, and also spices and food additives.- NMR (Nuclear magnetic resonance)
ΝΜR enables a collection of comprehensive metabolic profiles that can be used for food authentication. Site-Specific Natural Isotopic Fractionation (SNIF-NMR), enables robust fingerprinting of natural molecules. A well-known application of SNIF-NMR is the determination of the geographical origin of the wine, developed by the EU in 1990 (EU regulations 2670/90, 2347/91, and 2348/91). Profiling methods such as non-targeted 1H-NMR analysis have been applied to assess food’s geographical provenance. NMR analysis has been used for assessing adulteration, such as red wine adulteration with anthocyanins, synthetic flavors sold as natural, and addition of cane or corn sugar to maple syrup. Discrimination of origin/adulteration cases by their metabolic profile using NMR includes wines, coffee, olive oils, honey, fish, spirits, vinegar, and saffron. 
- Sensory Analysis
Instrumental tests of food quality using perception sensors instead of human panel tests is attracting massive attention recently. Amongst the techniques, there is a clear need to refer to Gas Chromatography Olfactometry (GCO), and biomimetic sensors: electronic tongue (e-tongue), electronic nose, (e-nose), electronic eye, (e-eye). The “e-nose” uses the detection of the volatile compounds present in the headspace of a food sample by an array of semi-selective gas sensors.
First, the headspace (volatile compounds) of a sample is generated and the headspace is injected into the detection system (sensors set). Each sensor is sensitive to all volatile molecules but each in its specific way. Most “e-noses” use sensor arrays that react to volatile compounds on contact: the adsorption of volatile compounds on the sensor surface causes a physical change of the sensor. A specific response is recorded by the electronic interface transforming the signal into a digital value. Recorded results are then computed based on statistical models.
Sensory analysis can be used for identifying the authenticity of foods are wines, olive oils, tea, beers and cheeses.- Nonchromatographic Mass Spectrometry
Nonchromatographic MS techniques have been applied in food authentication to uncover incorrect descriptions and mislabelling of foods with specific geographical label such as saffron, truffle, honey, beer, olive oils, juices, and botanical origin of spices and species. These techniques are also used to prevent food fraud such as dilution of olive oil with cheaper vegetable oils, and adulteration of donkey milk, of higher value types of milk (sheep’s and goat’s) with milk of lower value (cow’s milk), of fresh cow’s milk with powdered milk, of coffee, and of animal feed.Enzyme-linked immunosorbent assay, ELISA, is the most used of immunological techniques. It has been used to verify the authenticity of several food commodities such as meat, fish, and dairy products. It can also detect the presence of genetically modified organisms (GMOs) and undeclared processes like food irradiation. Food authenticity assessment by immunological techniques includes the determination of osteocalcin in meat and bone meal, detection of glucomannan (use is banned in Europe) in konjac plant products, detection of melamine and bovine IgG in milk, and detection of pork in ground beef and soybean proteins in meat products.
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