Validation of a fast real-time PCR method to detect fraud and mislabeling in milk and dairy products

Rapid authentication of characteristic milk powders by recombinase polymerase amplification assays

The authentication of dairy species has great significance for food safety. This study focused on a more rapid method for identifying major dairy species, and specific recombinase polymerase amplification (RPA)-based assays for cattle, goat, sheep, camel and donkey were developed. Through the developed RPA-based assays, goats and sheep could be simultaneously identified and bovine families could be differentiated. The performances of the RPA assays were validated using 37 milk powder samples, of which 16.2% (6/37) were suspected of being adulterated and 24.3% (9/37) were potentially at risk of being wrongly identified as adulteration. The effectiveness of the developed assays for crude DNA detection was also validated by a rapid nucleic acid extraction kit, and results showed that the presence of large amounts of protein and fat did not affect the qualitative results. Therefore, these assays could combine with the rapid nucleic acids extraction methods for being used in field detection.

Research advances in detection of food adulteration and application of MALDI-TOF MS: A review

Food adulteration and illegal supplementations have always been one of the major problems in the world. The threat of food adulteration to the health of consumers cannot be ignored. Food of questionable origin causes economic losses to consumers, but the potential health risks cannot be ignored. However, the traditional detection methods are time-consuming and complex. This review mainly discusses the types of adulteration and technologies used to detect adulteration. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is also emphasized in the detection of adulteration and authenticity of origin analysis of various types of food (milk, meat, edible oil, etc.), and the future application direction and feasibility of this technology are analyzed. On this basis, MALDI-TOF MS was compared with other detection methods, highlighting the advantages of this technology in the detection of food adulteration. The future development prospect and direction of this technology are also emphasized.

Double-Tube Multiplex TaqMan Real-Time PCR for the Detection of Eight Animal-Derived Dairy Ingredients

Milk and dairy products represent important sources of nutrition in our daily lives. The identification of species within dairy products holds importance for monitoring food adulteration and ensuring traceability. This study presented a method that integrated double-tube and duplex real-time polymerase chain reaction (PCR) with multiplex TaqMan probes to enable the high-throughput detection of animal-derived ingredients in milk and dairy products. The detection system utilized one pair of universal primers, two pairs of specific primers, and eight animal-derived specific probes for cow, buffalo, goat, sheep, camel, yak, horse, and donkey. These components were optimized within a double-tube and four-probe PCR multiplex system. The developed double-tube detection system could simultaneously identify the above eight targets with a detection limit of 10-0.1 pg/μL. Validation using simulated adulterated milk samples demonstrated a detection limit of 0.1%. The primary advantage of this method lies in the simplification of the multiplex quantitative real-time PCR (qPCR) system through the use of universal primers. This method provides an efficient approach for detecting ingredients in dairy products, providing powerful technical support for market supervision.

A rapid and sensitive aptamer-based biosensor for beta-lactoglobulin in milk

Beta-lactoglobulin (β-Lg), a prominent milk protein, is a major contributor to milk allergies. The quantitative assessment of β-Lg is a valuable method for assessing the allergenic potential of dairy products. In this study, a specific aptamer, β-Lg-01, with an affinity constant (KD) of 28.6 nM for β-Lg was screened through seven rounds of magnetic bead SELEX (MB-SELEX). A novel bio-layer interferometry (BLI)-based aptasensor was developed, which had a limit of detection (LOD) of 0.3 ng mL-1, a linear range of 1.5 ng mL-1-15 μg mL-1, and a recovery rate of 102-116% among the milk samples. This aptasensor provides a potential tool for the detection and risk assessment of β-Lg within 10 min.

High-resolution melting real-time PCR assays for subtyping of five diarrheagenic Escherichia coli by a single well in milk

Diarrheagenic Escherichia coli (DEC) is a kind of foodborne pathogen that poses a significant threat to both food safety and human health. To address the current challenges of high prevalence and difficult subtyping of DEC, this study developed a method that combined multiplex polymerase chain reaction (PCR) with high resolution melting (HRM) analysis for subtyping 5 kinds of DEC. The target genes are amplified by multiplex PCR in a single well, and HRM curve analysis was applied for distinct amplicons based on different melting temperature (Tm) values. The method enables discrimination of different DEC types based on characteristic peaks and distinct Tm values in the thermal melting curve. The assay exhibited 100% sensitivity and 100% specificity with a detection limit of 0.5-1 ng/μL. The results showed that different DNA concentrations did not influence the subtyping results, demonstrating this method owed high reliability and stability. In addition, the method was also used for the detection and subtyping of DEC in milk. This method streamlines operational procedures, shorts the detection time, and offers a novel tool for subtyping DEC.

Discriminant Analysis of Aroma Differences between Cow Milk Powder and Special Milk Powder (Donkey, Camel, and Horse Milk Powder) in Xinjiang Based on GC-IMS and Multivariate Statistical Methods

In order to explore the aromatic differences between Xinjiang cow milk powder and specialty milk powder (donkey, camel, and horse milk powder), Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) analysis was employed to investigate the volatile compounds in these four types of milk powders. A total of 61 volatile substances were detected, with ketones, aldehydes, and alcohols being the primary flavor components in the milk powders. While the aromatic components of the different milk powders showed similarities in terms of types, there were significant differences in their concentrations, exhibiting distinct characteristics for each type. The Partial Least Squares Discriminant Analysis (PLS-DA) showed that there were 15, 14, and 23 volatile compounds that could be used for discrimination of cow milk powder against specialty milk powders, respectively. And it was validated by Receiver Operating Characteristic (ROC) analysis, and finally, 8, 6, and 19 volatile compounds were identified as valid differential marker substances. To facilitate visual discrimination between the different milk powders, we established GC-IMS fingerprint spectra based on the final discriminant markers. These studies provide theoretical guidance for the application of volatile compounds to discriminate adulteration of milk powder marketed in Xinjiang.

Assessment of cheese frauds, and relevant detection methods: A systematic review

Dairy products are widely consumed in the world due to their nutritional and functional characteristics. This group of food products are consumed by all age groups due to their health-giving properties. One of these products is cheese which has a high price compared to other dairy products. Because of this, it can be prone to fraud all over the world. Fraud in food products threatens the world's food safety and can cause serious damage to human health. There are many concerns among food authorities in the world about the fraud of food products. FDA, WHO, and the European Commission provide different legislations and definitions for fraud. The purpose of this review is to identify the most susceptible cheese type for fraud and effective methods for evaluating fraud in all types of cheeses. For this, we examined the Web of Science, Scopus, PubMed, and ScienceDirect databases. Mozzarella cheese had the largest share among all cheeses in terms of adulteration due to its many uses. Also, the methods used to evaluate different types of cheese frauds were PCR, Spectrometry, stable isotope, image analysis, electrophoretic, ELISA, sensors, sensory analysis, near-infrared and NMR. The methods that were most used in detecting fraud were PCR and spectrometry methods. Also, the least used method was sensory evaluation.

Mitochondrial DNA D-Loop Amplification and Sequencing for Species Differentiation in Milk

Adulteration of dairy products, mainly through the substitution of high-quality milk for lower-quality milk, results in the production of low-value products, raising health, social, and economic concerns. As such, the development of methods to ensure dairy products' safety and quality is of great concern for governments and consumers. Although several methods have been developed for species differentiation in dairy products, their application and the establishment of reliable molecular markers for authentication purposes still need to be improved. In this chapter, we describe a low-cost, sensitive, fast, and reliable PCR-based method for mitochondrial D-loop DNA amplification for efficient detection of cattle milk in binary mixtures with sheep milk, thereby allowing the authentication of processed dairy products.

Detection and quantification of adulteration in milk and dairy products: A novel and sensitive qPCR-based method

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A novel qPCR method was able to detect and quantify cow, buffalo, goat and sheep DNA in milk and dairy products.

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Established detection limit was 0.016 ng for the four species.

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The limit of detection of cow DNA in buffalo, goat and sheep DNA samples was 0.1% (0.01 ng)

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This method is able to detect and quantify adulteration between cows, buffaloes, goats and sheep dairy samples.

Species identification in dairy products has a notable importance in food traceability and adulteration control and consequently has a significant effect on the final economic value of foods. In the present study, we developed a method based on real-time quantitative PCR (qPCR) for detection and quantification of cow DNA in DNA samples from milk and dairy products from buffaloes, goats, and sheep. The qPCR reactions showed high specificity, and the amplifications only occurred to species-specific primers. The calibration curves allowed for the quantification of the amount of DNA of each species-specific primer, and the established detection limit was 0.016 ng for the four species. The detection limit of cow DNA in buffalo, goat and sheep DNA samples was 0.1% (0.01 ng). Although the present study aimed to detect and quantify cow DNA in buffalo, goat, and sheep dairy products, we believe that the qPCR assays can also be directed to differentiate and quantify goat × sheep, and/or buffalo × goat/sheep.

Animal Species Authentication in Dairy Products

Milk is one of the most important nutritious foods, widely consumed worldwide, either in its natural form or via dairy products. Currently, several economic, health and ethical issues emphasize the need for a more frequent and rigorous quality control of dairy products and the importance of detecting adulterations in these products. For this reason, several conventional and advanced techniques have been proposed, aiming at detecting and quantifying eventual adulterations, preferentially in a rapid, cost-effective, easy to implement, sensitive and specific way. They have relied mostly on electrophoretic, chromatographic and immunoenzymatic techniques. More recently, mass spectrometry, spectroscopic methods (near infrared (NIR), mid infrared (MIR), nuclear magnetic resonance (NMR) and front face fluorescence coupled to chemometrics), DNA analysis (real-time PCR, high-resolution melting analysis, next generation sequencing and droplet digital PCR) and biosensors have been advanced as innovative tools for dairy product authentication. Milk substitution from high-valued species with lower-cost bovine milk is one of the most frequent adulteration practices. Therefore, this review intends to describe the most relevant developments regarding the current and advanced analytical methodologies applied to species authentication of milk and dairy products.

Identification of milk from different animal and plant sources by desorption electrospray ionisation high-resolution mass spectrometry (DESI-MS)

This study used desorption electrospray ionisation mass spectrometry (DESI-MS) to analyse and detect and classify biomarkers in five different animal and plant sources of milk for the first time. A range of differences in terms of features was observed in the spectra of cow milk, goat milk, camel milk, soya milk, and oat milk. Chemometric modelling was then used to classify the mass spectra data, enabling unique or significant markers for each milk source to be identified. The classification of different milk sources was achieved with a cross-validation percentage rate of 100% through linear discriminate analysis (LDA) with high sensitivity to adulteration (0.1-5% v/v). The DESI-MS results from the milk samples analysed show the methodology to have high classification accuracy, and in the absence of complex sample clean-up which is often associated with authenticity testing, to be a rapid and efficient approach for milk fraud control.

DNA-Based Tools to Certify Authenticity of Rice Varieties—An Overview

Rice (Oryza sativa L.) is one of the most cultivated and consumed crops worldwide. It is mainly produced in Asia but, due to its large genetic pool, it has expanded to several ecosystems, latitudes and climatic conditions. Europe is a rice producing region, especially in the Mediterranean countries, that grow mostly typical japonica varieties. The European consumer interest in rice has increased over the last decades towards more exotic types, often more expensive (e.g., aromatic rice) and Europe is a net importer of this commodity. This has increased food fraud opportunities in the rice supply chain, which may deliver mixtures with lower quality rice, a problem that is now global. The development of tools to clearly identify undesirable mixtures thus became urgent. Among the various tools available, DNA-based markers are considered particularly reliable and stable for discrimination of rice varieties. This review covers aspects ranging from rice diversity and fraud issues to the DNA-based methods used to distinguish varieties and detect unwanted mixtures. Although not exhaustive, the review covers the diversity of strategies and ongoing improvements already tested, highlighting important advantages and disadvantages in terms of costs, reliability, labor-effort and potential scalability for routine fraud detection.

Species identification of ruminant milk by genotyping of the κ-casein gene

The development of molecular genetic and bioinformatic systems for identifying the species of milk and the raw material composition of dairy products is of great scientific and practical importance with the purpose of introducing developments in the system for controlling the turnover of falsified products. The aim of the research is to develop a method of PCR-RFLP analysis for species identification of milk and dairy products from agricultural ruminant animals by the κ-casein gene (CSN3) with the possibility of qualitative and relative quantitative assessment of species-specific DNA of the tested biomaterial. The objects of research were samples of raw milk and milk powder, pasteurized cream, and hard and semi-hard cheeses. The developed method of species identification of milk and dairy products includes sample preparation of the studied samples, nucleic acid extraction, combined PCR-RFLP technique, detection of obtained results by the method of horizontal electrophoresis in agarose gel and their analysis, including using the developed mathematical algorithms and software. The synergistic effect established in combined operation of 2 restriction enzymes ensured their application in a mix with increased performance in an ergonomic way in the context of DNA authentication of cow, goat, and sheep milk and dairy products based on them. The specificity and sensitivity of the proposed method is potentially suitable for implementing the development of a system to control the turnover of falsified and counterfeit goods.

Authenticity assessment of dairy products by capillary electrophoresis

Milk and derivatives are a very important part in the diet of the world population. Products from goat, buffalo, and sheep species have a greater economic value than the cow ones, therefore, authenticity frauds by improperly adding cow's milk occur frequently: dairy products are among the seven more attractive foods for adulteration. Milk from each of the above-cited animal species has its own definite profile of whey proteins (variants of α-lactalbumin and β-lactoglobulin) and its definite profile of caseins (variants of α_S1 -, α_S2 -, β-, and κ-casein). Such proteins can be usefully exploited as markers of authenticity by using capillary electrophoresis which is the technique of choice for the analysis of proteins. Due to the multiple adjustable parameters that are unknown to other analytical techniques, capillary electrophoresis is able to detect frauds in milk mixtures and cheese with little use of solvents, fast analysis time, and ease of operation. This makes it attractive and competitive for routine checks that are very important to fight the adulteration market. Advantages and limitations are discussed.

Droplet Digital PCR (ddPCR) Analysis for the Detection and Quantification of Cow DNA in Buffalo Mozzarella Cheese

Simple Summary

Buffalo mozzarella cheese, sold as a Protected Designation of Origin (PDO) product, is made exclusively from Mediterranean buffalo (Bubalus bubalis) milk. To maximize their profits and overcome seasonal shortages of buffalo milk, some producers have started to produce “PDO” buffalo mozzarella cheese by adulterating buffalo milk with milk from different species. such as bovine, thus defrauding consumers. This practice has led the Italian government to reinforce controls on food mislabeling and fraud through traceability mechanisms. The aim of this work is the development of a molecular assay—droplet digital Polymerase Chain Reaction technique (ddPCR)—able to detect the DNA of cow and/or buffalo milk in PDO buffalo mozzarella cheese, thus revealing fraud. The results have highlighted that, thanks to its high precision and sensitivity, the ddPCR could represent an efficacious means of supporting the official controls aimed at combating the adulteration of buffalo mozzarella cheese with bovine milk.

Abstract

Buffalo mozzarella cheese is one of the most appreciated traditional Italian products and it is certified as a Protected Designation of Origin (PDO) product under the European Commission Regulation No. 1151/2012. It is obtained exclusively from buffalo milk. If made from cow milk, or a mixture of buffalo and cow milk, buffalo mozzarella cheese does not qualify as a PDO product. In order to maximize their profits, some producers market buffalo mozzarella that also contains cow milk as a PDO product, thus defrauding consumers. New methods for revealing this fraud are therefore needed. One such method is the droplet digital Polymerase Chain Reaction (ddPCR). Thanks to its high precision and sensitivity, the ddPCR could prove an efficacious means for detecting the presence of cow milk in buffalo mozzarella cheese that is marketed as a PDO product. ddPCR has proved able to detect the DNA of cow and/or buffalo milk in 33 buffalo mozzarella cheeses labelled as PDO products, and experimental evidence could support its application in routine analyses.

Short communication: Detection of undeclared presence of bovine milk in buffalo yogurt

The authenticity of buffalo (Bubalus bubalis) dairy products is a focal issue, considering the increasing demand for buffalo milk products. Therefore, the aim of this study was to investigate the undeclared presence of bovine (Bos taurus) milk in buffalo yogurt, to understand which risk factors might make the product vulnerable to fraud. Real-time PCR assay showed the undeclared presence of bovine DNA in addition to buffalo DNA in 18 of 72 samples. Given the widespread lack of data on the presence of undeclared milk species in buffalo dairy products, the study provides a significant insight into the incidence of fraud in the buffalo dairy field. The data from this study could help improve the analysis of food safety risks along the buffalo milk supply chain and in the dairy processing industry, perceived as being highly vulnerable to food fraud, and prioritize target areas for food policy making to steer and enforce European food fraud regulations.

Simultaneous detection of ovine and caprine DNA in meat and dairy products using triplex TaqMan real-time PCR

In this study, we report a new approach for the detection of ovine and caprine DNA in meat and dairy products using real-time PCR protocol. Our new approach is based on the use of endogenous control and species-specific TaqMan fluorescence probes. With this methodology, we specifically detected ovine and caprine DNA in meat and dairy products, with limits of detection of 0.001 ng and 0.01 ng for fresh and processed ovine meats, respectively, and 0.00025 ng, 0.005 ng, and 0.01 ng for caprine meat, milk, and cheese, respectively. Artificial meat and milk mixtures from sheep and goat were used to validate the protocol. Our results support that TaqMan real-time PCR with endogenous control is an efficient and accurate method to detect DNA from sheep and goat in meat and dairy products.

A barcode-DNA analysis method for the identification of plant oil adulteration in milk and dairy products

In the present work, a barcode-DNA analysis method is described for the detection of plant oil adulteration in milk and dairy products. The method relies on the fact that plant DNA should not be present in readily detectable amounts in a dairy product unless it contains undeclared plant material. Thus, a universal plant barcode is chosen as the target to be amplified from dairy samples. Accordingly, barcode PCR-CE (PCR-capillary electrophoresis) assays are described, which do not require preliminary information on the species source of the adulterant oil type. Two PCR-CE assays, one operating on the plastid trnL (UAA) intron and the other targeting its inner P6 loop in nested format, were shown to detect corn, soybean, rapeseed and sunflower oils in clarified butter, milk and yogurt. Both barcodes are robustly amplified with extremely conserved primers. While the intron provides the species discrimination ability, the P6 loop provides superior detection sensitivity.

Triplex real-time PCR assay for the authentication of camel-derived dairy and meat products

Authentication of dairy and meat products is important to ensure fair competition, consumer benefit, and food safety. The large difference in price between camel and cow milk may be an incentive to adulterate camel dairy products with cow-derived foodstuffs. However, no studies so far have used triplex real-time PCR with an endogenous control to identify camel and cow origins in dairy and meat products. In this study, we developed a triplex real-time PCR assay based on amplification of mitochondrial 12S ribosomal DNA for the authentication of camel-derived dairy and meat products. This method was applied to identify camel and cow DNA in milk, yogurt, cheese, milk powder, milk beverage, meat products, and mixtures with milk and meat. Concentrations as low as 1 to 5% and 0.1% camel milk and meat, respectively, were detected in the mixtures, and 1 to 5% and 0.1% cow milk and meat, respectively, were identified via this approach. The limits of detection were 0.005 to 0.0025 ng, 0.05 to 0.001 ng, 0.001 to 0.0005 ng, and 0.00025 to 0.0001 ng of DNA in camel milk, camel yogurt, commercial camel milk beverage, and camel meat, and from 0.0025 to 0.001 ng, 0.5 to 0.001 ng, 1 to 0.05 ng, 0.01 ng, 0.001 ng, 0.0005 to 0.00025 ng, 0.0005 to 0.00025 ng, and 0.005 ng of DNA from cow milk, yogurt, cheese, acidic whey, milk powder, beef, beef jerky, and beef sausage, respectively. Different dairy and meat samples of camel and cow origins had a range of authentication limits and limits of detection. The designed triplex real-time PCR assay was shown to be a specific, sensitive, and efficient technique for the identification of camel and cow DNA in foodstuffs.

Paper-based DNA biosensor for food authenticity testing

A paper-based DNA biosensor was developed for food authenticity testing using dairy products as a model. DNA from milk-based samples was isolated, and species-specific DNA sequences were amplified and identified by the biosensor using specific DNA probes. The properties of gold nanoparticles were exploited for visual detection. The biosensor was applied for detection of three species, namely cow, sheep and goat, while as low as 1.6 fmol for cow and goat, and 3.1 fmol for sheep PCR product were detected. Moreover, adulteration down to 0.01% could be detected, based on binary mixtures of cows', ewes' and goats' milk yogurt, containing 0.01 to 5% of cows' yogurt in ewes' and goats' yogurts, respectively. The proposed paper-based DNA biosensor offered 10 times higher detectability than other methods, good specificity and reproducibility, and could be applied easily for the detection of other adulterated food products, such as meat, olive oil and legumes.

Discrimination of Milk from Different Animal Species by a Foodomics Approach Based on High-Resolution Mass Spectrometry

An untargeted foodomics strategy based on ultra-high-performance liquid chromatography coupled with quadrupole orbitrap and chemometrics was used to observe subtle differences in the molecule profiles of raw milk from different animal species (cow milk, goat milk, and water buffalo milk), which could prevent the fraud activities in the dairy industry. In data-dependent acquisition (DIA), spectra for all precursor ions facilitated the comprehensive identification of unknown compounds in untargeted foodomics. Chemometrics techniques were used to analyze large amounts of complex data to observe the separation of different sample groups and find the potential markers of sample groups. Finally, five markers were putatively identified by the potential marker identification workflow. The quantification results showed that β-carotene was found only in cow milk; ergocalciferol was found only in water buffalo milk; and the contents of nonanoic acid, decanoic acid, and octanoic acid were higher in goat milk than those in cow milk and water buffalo milk. The quantification of β-carotene enabled the detection of cow milk with a sensitivity threshold of 5% (w/w). This work provided an efficient approach for the discrimination of cow milk, goat milk, and water buffalo milk. Compared with proteomics and genomics, the simpler analytical procedures, lower costs, and higher speed of this work make it of great benefit for routine operations.

TaqMan real-time quantitative PCR for identification of antlers in tradition Chinese medicine

In this study, a method was established for discriminating the true Cervus antlers from its counterfeits using TaqMan real-time quantitative PCR. The method combines the use of true Cervus antlers-specific primers, that amplify a 226 bp fragment from true Cervus antlers DNA, and mammalian-specific primers amplifying a 146 bp fragment from mammalian species DNA, which are used as endogenous control. A TaqMan probe that hybridizes in the 'Cervus antler' and also in the 'mammalian' DNA fragments is used to monitor the amplification of the target gene. The Cervus antler mitochondrial DNA was used as target gene to design the primers and TaqMan probes. The data revealed that the TaqMan real-time PCR-based assay can be used for identification of the true Cervus antlers from counterfeits in a single step. The limit of detection (LOD) was lower than 1 pg of DNA per reaction.

Nano-Biosensing Platforms for Detection of Cow's Milk Allergens: An Overview

Among prevalent food allergies, cow milk allergy (CMA) is most common and may persist throughout the life. The allergic individuals are exposed to a constant threat due to milk proteins' presence in uncounted food products like yogurt, cheese, and bakery items. The problem can be more severe due to cross-reactivity of the milk allergens in the food products due to homologous milk proteins of diverse species. This problem can be overcome by proper and reliable food labeling in order to ensure the life quality of allergic persons. Therefore, highly sensitive and accurate analytical techniques should be developed to detect the food allergens. Here, significant research advances in biosensors (specifically immunosensors and aptasensors) are reviewed for detection of the milk allergens. Different allergic proteins of cow milk are described here along with the analytical standard methods for their detection. Additionally, the commercial status of biosensors is also discussed in comparison to conventional techniques like enzyme-linked immunosorbent assay (ELISA). The development of novel biosensing mechanisms/kits for milk allergens detection is imperative from the perspective of enforcement of labeling regulations and directives keeping in view the sensitive individuals.

Verification of cheeses authenticity by mass spectrometry

Cheeses are a group of fermented dairy products that are produced all over the world in various forms and flavours. Milk, especially sheep or goat milk, is still regarded as an expensive raw material in the world, which makes milk and milk products highly attractive as a fraud target. Most often, such fraud includes partial or complete substitution with cheaper sorts of milk (e.g. bovine milk). The aim of this work was to verify the authenticity of 27 cheeses commonly emerging on the Czech food market. The cheeses were distinguished on the basis of milk animal species origin. For this purpose, two mass spectrometry techniques were used: matrix-assisted laser desorption/ionization with time of flight mass spectrometry together with principal component analysis method and liquid chromatography coupled with electrospray ionization and quadrupole time-of-flight mass spectrometry. The results were a partial success, because the cheeses could only be partially distinguished with the first mass spectrometry technique probably because of the influence of some protein additive materials in cheeses. The second technique allowed for collecting higher quality results and thus appears to be highly suitable for the research task.

Review of Recent DNA-Based Methods for Main Food-Authentication Topics

Adulteration and mislabeling of food products and the commercial fraud derived, either intentionally or not, is a global source of economic fraud to consumers but also to all stakeholders involved in food production and distribution. Legislation has been enforced all over the world aimed at guaranteeing the authenticity of the food products all along the distribution chain, thereby avoiding food fraud and adulteration. Accordingly, there is a growing need for new analytical methods able to verify that all the ingredients included in a foodstuff match the qualities claimed by the manufacturer or distributor. In this sense, the improved performance of most recent DNA-based tools in term of sensitivity, multiplexing ability, high-throughput, and relatively low-cost give them a game-changing role in food-authenticity-related topics. Here, we provide a thorough and updated vision on the recently reported approaches that are applying these DNA-based tools to assess the authenticity of food components and products.

The role of molecular genetics in livestock production

Genetic variations that lead to easy-to-identify phenotypic changes have always been of interest to livestock breeders since domestication. Molecular genetics has opened up possibilities for identifying these variations and understanding their biological and population effects. Moreover, molecular genetics is part of the most diverse approaches and applications in animal production nowadays, including paternity testing, selection based on genetic variants, diagnostic of genetic diseases, reproductive biotechniques, fraud identification, differentiation of hybrids, parasite identification, genetic evaluation, diversity studies, and genome editing, among others. Therefore, the objective of this review was to describe the different applications of molecular genetics in livestock production, contextualising them with examples and highlighting the importance of the study of these topics and their applications.

A new fast real-time PCR method for the identification of three sibling Apodemus species (A. sylvaticus, A. flavicollis, and A. alpicola) in Italy

The identification of field mice Apodemus flavicollis, Apodemus sylvaticus, and Apodemus alpicola represents a challenge for field scientists due to their highly overlapping morphological traits and habitats. Here, we propose a new fast real-time PCR method to discriminate the three species by species-specific TaqMan assays. Primers and probes were designed based on the alignment of 54 cyt-b partial sequences from 25 different European countries retrieved from GenBank. TaqMan assays were then tested on 133 samples from three different areas of Italy. Real-time PCR analysis showed 92 samples classified as A. flavicollis, 13 as A. sylvaticus, and 28 as A. alpicola. We did not observe any double amplification and DNA sequencing confirmed species assignment obtained by the TaqMan assays. The method is implementable on different matrices (ear tissues, tail, and blood). It can be used on dead specimens or on alive animals with minimally invasive sampling, and given the high sensitivity, the assay may be also suitable for degraded or low-DNA samples. The method proved to work well to discriminate between the species analyzed. Furthermore, it gives clear results (amplified or not) and it does not require any postamplification handling of PCR product, reducing the time needed for the analyses and the risk of carryover contamination. It therefore represents a valuable tool for field ecologists, conservationists, and epidemiologists.

Direct duplex real-time loop mediated isothermal amplification assay for the simultaneous detection of cow and goat species origin of milk and yogurt products for field use

A multiple loop-mediated isothermal amplification (LAMP) method was developed to detect cow and goat milk in the field using a portable fluorescence device. For rapid on-site detection, this duplex LAMP assay was used in combination with direct amplification, without DNA extraction. The cow- and goat-specific LAMP primer sets were designed based on the mitochondrial cytochrome b gene, and showed specificity against 13 other animal species in the reactions. The sensitivity of the duplex LAMP assay for cow and goat was 0.1 and 1 pg, respectively. The detection limit for both target species in milk mixtures was 2%. This assay successfully amplified and identified the two target species in 24 samples of commercial milk and yogurt products, with 30 min sampling-to-result analysis time. Therefore, this direct duplex real-time LAMP assay is useful for on-site simultaneous detection of cow and goat milk in commercial products, a capability needed to confirm accurate labeling.

Authentication of caprine milk and cheese by commercial qPCR assay

The objective of the study was to investigate potential adulteration of commercial caprine milks and cheeses with bovine milk using commercial qPCR assay. The assay comprised of bovine-, ovine- and caprine-specific primers and TaqMan probe and mammalian internal control. Specificity, sensitivity, linearity, reproducibility and efficiency of the bovine assay were tested as well. Specificity was verified by running reaction on the DNA of other milk-producing species (caprine and ovine) and made-up bovine-caprine (v/v) milk mixes. In both experiments, a bovine DNA fragment was amplified whereas no amplification was obtained from the other species. Sensitivity, linearity, reproducibility and efficiency were tested on 10-fold dilution series of 10 ng bovine DNA. The assay has shown good linearity (R2 = 0.983) within whole range, with efficiency of 86% and excellent reproducibility (SD around the CT for the technical replicates <0.5). The sensitivity was adequate, as calculated LOD and LOQ were 1.44 pg and 2.94 pg of bovine DNA, respectively. Finally, the assay was used to authenticate 5 caprine milk samples and 5 caprine cheese samples, purchased from local supermarkets. Totally, 1 milk sample has shown the fluorescence signal, which exceeded baseline in cycle 39.01 ±0.69. However, the signal was above LOD and LOQ suggesting that there could not be unambiguously declared any adulteration with bovine milk. Amplification of bovine-specific DNA was not observed in the other samples indicating products were not adulterated. The commercial qPCR assay has proved that real-time PCR assays, as well as DNA-based techniques in a general, are the excellent and reliable tools for fighting with frauds in the food industry and protecting the public health. 

Rapid capillary electrophoresis approach for the quantification of ewe milk adulteration with cow milk

The substitution of ewe milk with more economic cow milk is a common fraud. Here we present a capillary electrophoresis method for the quantification of ewe milk in ovine/bovine milk mixtures, which allows for the rapid and inexpensive recognition of ewe milk adulteration with cow milk. We utilized a routine CE method for human blood and urine proteins analysis, which fulfilled the separation of skimmed milk proteins in alkaline buffer. Under this condition, ovine and bovine milk exhibited a recognizable and distinct CE protein profiles, with a specific ewe peak showing a reproducible migration zone in ovine/bovine mixtures. Based on ewe specific CE peak, we developed a method for ewe milk quantification in ovine/bovine skimmed milk mixtures, which showed good linearity, precision and accuracy, and a minimum amount of detectable fraudulent cow milk equal to 5%.