A Fast and Reliable Real-Time PCR Method for Detection of Ten Animal Species in Meat Products

Development of a real-time PCR protocol for the detection of chicken DNA in meat products

Food falsification is a pressing issue in today's food industry, with fraudulent substitution of costly ingredients with cheaper alternatives occurring globally. Consequently, developing straightforward and efficient diagnostic systems to detect such fraud is a top priority in scientific research. The aim of the work was to develop a test system and protocol for polymerase chain reaction (PCR) to detect in food products of animal origin the substitution of expensive meat raw materials for by-products of poultry processing. For this, real-time polymerase chain reaction (RT-PCR) was used, which allows determining the qualitative and quantitative substitution in raw and technologically prepared products. Other methods for detecting falsification - enzyme immunoassay (ELISA/ELISA) or express methods in the form of a lateral flow immunoassay are less informative. The extraction of nucleic acids for real-time polymerase chain reaction depends on the source matrix, with higher concentrations obtained from germ cells and parenchymal organs. Extraction from muscle and plant tissues is more challenging, but thorough grinding of these samples improves nucleic acid concentration by 1.5 times using DNA extraction kits. The selection of primers and fluorescent probes through GenBank and PCR Primer Design/DNASTAR software enables efficient amplification and identification of target chicken DNA fragments in various matrices.

A review of CRISPR-Cas and PCR-based methods for the detection of animal species in the food chain-current challenges and future prospects

Regular testing and systematic investigation play a vital role to ensure product safety. Until now, the existing food authentication techniques have been based on proteins, lipids, and nucleic acid-based assays. Among various deoxyribonucleic acid (DNA)-based methods, the recently developed Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) based bio-sensing is an innovative and fast-expanding technology. The CRISPR/Cas-9 is known as Clustered Regularly Interspaced Short Palindromic Repeats due to the flexibility and simplicity of the CRISPR/Cas9 site-specific editing tool has been applied in many biological research areas such as Gene therapy, cell line development, discovering mechanisms of disease, and drug discovery. Nowadays, the CRISPR-Cas system has also been introduced into food authentication via detecting DNA barcodes of poultry and livestock both in processed and unprocessed food samples. This review documents various DNA based approaches, in an accessible format. Future CRISPR technologies are forecast while challenges are outlined.

Simple and field-adapted species identification of biological specimens combining multiplex multienzyme isothermal rapid amplification, lateral flow dipsticks, and universal primers for initial rapid screening without standard PCR laboratory

Species identification of biological specimens can provide the valuable clues and accelerate the speed of prosecution material processing for forensic investigation, especially when the case scene is inaccessible and the physical evidence is cumbersome. Thus, establishing a rapid, simple, and field-adapted species identification method is crucial for forensic scientists, particularly as first-line technology at the crime scene for initial rapid screening. In this study, we established a new field-adapted species identification method by combining multiplex multienzyme isothermal rapid amplification (MIRA), lateral flow dipstick (LFD) system, and universal primers. Universal primers targeting COX I and COX II genes were used in multiplex MIRA-LFD system for seven species identification, and a dedicated MIRA-LFD system primer targeting CYT B gene was used to detect the human material. DNA extraction was performed by collecting DNA directly from the centrifuged supernatant. Our study found that the entire amplification process took only 15 min at 37 °C and the results of LFDs could be visually observed after 10 min. The detection sensitivity of human material could reach 10 pg, which is equivalent to the detection of single cell. Different common animal samples mixed at the ratio of 1 ng:1 ng, 10 ng:1 ng, and 1 ng:10 ng could be detected successfully. Furthermore, the damaged and degraded samples could also be detected. Therefore, the convenient, feasible, and rapid approach for species identification is suitable for popularization as first-line technology at the crime scene for initial rapid screening and provides a great convenient for forensic application.

Rapid Full-Cycle Technique to Control Adulteration of Meat Products: Integration of Accelerated Sample Preparation, Recombinase Polymerase Amplification, and Test-Strip Detection

Verifying the authenticity of food products is essential due to the recent increase in counterfeit meat-containing food products. The existing methods of detection have a number of disadvantages. Therefore, simple, cheap, and sensitive methods for detecting various types of meat are required. In this study, we propose a rapid full-cycle technique to control the chicken or pig adulteration of meat products, including 3 min of crude DNA extraction, 20 min of recombinase polymerase amplification (RPA) at 39 °C, and 10 min of lateral flow assay (LFA) detection. The cytochrome B gene was used in the developed RPA-based test for chicken and pig identification. The selected primers provided specific RPA without DNA nuclease and an additional oligonucleotide probe. As a result, RPA-LFA, based on designed fluorescein- and biotin-labeled primers, detected up to 0.2 pg total DNA per μL, which provided up to 0.001% w/w identification of the target meat component in the composite meat. The RPA-LFA of the chicken and pig meat identification was successfully applied to processed meat products and to meat after heating. The results were confirmed by real-time PCR. Ultimately, the developed analysis is specific and enables the detection of pork and chicken impurities with high accuracy in raw and processed meat mixtures. The proposed rapid full-cycle technique could be adopted for the authentication of other meat products.

Identification of sheep (Ovis aries) meat by alkaline lysis-loop mediated isothermal amplification technique targeting mitochondrial D-loop region

Identification of meat species origin using reliable techniques is a critical requirement for ensuring label compliance, protection of consumer preference and prevention of fraudulence in the meat trade. Although a plethora of protein and DNA based meat species identification techniques are in vogue, need for rapid test suitable for under-resourced laboratories catering point-of-care (PoC) services was construed. Present study deals with development of rapid sheep (Ovis aries) meat identification technique using DNA extraction by alkaline lysis (AL) and loop-mediated isothermal amplification (LAMP) technique. The AL-LAMP specifically amplifies sheep-specific signal of mitochondrial D loop region under an isothermal temperature of 60 °C with an analytical sensitivity of 0.5 ng sheep DNA. The test was highly specific to sheep and performed well even in the presence of DNA of closely related meat animal species such as goat, cattle, buffalo and chicken. The novel primers designed for the AL-LAMP successfully detected sheep meat in raw and cooked meat samples heated up to 121 °C for 30 min. Sheep-specific AL-LAMP assay could detect 0.1% mutton-in-beef adulteration. Novel AL-LAMP assay being simple, rapid and reliable for sheep meat authentication in just 120 min; hence, it could be conveniently used by terminal laboratories engaged in rendering on-site or PoC services.

Evaluation of High Resolution Melting (HRM) Analysis for Meat Species Identification of Raw and Cooked Meat

The current study aimed to examine a real-time PCR assay with high-resolution melting (HRM) analysis for the species identification of minced meat samples. Meat samples from several animal species were purchased and minced separately or as a mixture of two species. DNA was extracted from all meat samples and subjected to real-time PCR assay by amplifying species-specific mitochondrial cytochrome b regions. Regarding the meat mixtures, two separate melting curves with specific melt peak temperatures (Tm) were detected. Additionally, DNA from each species was quantified, based on the calibration curves. The results showed that a real-time PCR assay with HRM analysis is suitable for the species identification of meat products, and could be used for the detection of meat frauds.

Detection of meat from horse, donkey and their hybrids (mule/hinny) by duplex real-time fluorescent PCR

Meat adulteration is currently a common practice worldwide. In China, adulteration of donkey meat products with the similar species (horse and mule/hinny) meat and mislabeling are becoming widespread concerns. In this study, a sensitive and species-specific duplex real-time PCR assay based on the simultaneous amplification of fragments of the creatine kinase muscle gene family, was developed and optimized for the identification of horse, donkey and mule /hinny species in raw and heat-processed meat products. Duplex real-time PCR results showed different fluorescence amplification curves for horse and donkey. Both kinds of fluorescence amplification curves appeared simultaneously for mule/hinny. The limit of detection (LOD) of the method was up to 0.01 ng /μL. The method and strategy developed in this study could be applied to detect the presence of adulterants from horse and mule /hinny meat in raw donkey meat and meat products.

Fraud in Animal Origin Food Products: Advances in Emerging Spectroscopic Detection Methods over the Past Five Years

Animal origin food products, including fish and seafood, meat and poultry, milk and dairy foods, and other related products play significant roles in human nutrition. However, fraud in this food sector frequently occurs, leading to negative economic impacts on consumers and potential risks to public health and the environment. Therefore, the development of analytical techniques that can rapidly detect fraud and verify the authenticity of such products is of paramount importance. Traditionally, a wide variety of targeted approaches, such as chemical, chromatographic, molecular, and protein-based techniques, among others, have been frequently used to identify animal species, production methods, provenance, and processing of food products. Although these conventional methods are accurate and reliable, they are destructive, time-consuming, and can only be employed at the laboratory scale. On the contrary, alternative methods based mainly on spectroscopy have emerged in recent years as invaluable tools to overcome most of the limitations associated with traditional measurements. The number of scientific studies reporting on various authenticity issues investigated by vibrational spectroscopy, nuclear magnetic resonance, and fluorescence spectroscopy has increased substantially over the past few years, indicating the tremendous potential of these techniques in the fight against food fraud. It is the aim of the present manuscript to review the state-of-the-art research advances since 2015 regarding the use of analytical methods applied to detect fraud in food products of animal origin, with particular attention paid to spectroscopic measurements coupled with chemometric analysis. The opportunities and challenges surrounding the use of spectroscopic techniques and possible future directions will also be discussed.

Current analytical methods for porcine identification in meat and meat products

Authentication of meat products is critical in the food industry. Meat adulteration may lead to religious apprehensions, financial gain and food-toxicities such as meat allergies. Thus, empirical validation of the quality and constituents of meat is paramount. Various analytical methods often based on protein or DNA measurements are utilized to identify meat species. Protein-based methods, including electrophoretic and immunological techniques, are at times unsuitable for discriminating closely related species. Most of these methods have been replaced by more accurate and sensitive detection methods, such as DNA-based techniques. Emerging technologies like DNA barcoding and mass spectrometry are still in their infancy when it comes to their utilization in meat detection. Gold nanobiosensors have shown some promise in this regard. However, its applicability in small scale industries is distant. This article comprehensively reviews the recent developments in the field of analytical methods used for porcine identification.

Development of a PCR-based assay for detection of Chinese mink tissue in meat products based on the mitochondrial DNA cytochrome-b gene

Species authentication of meat product origins has become an important subject for ensuring the health of consumers. Based on the cytochrome b gene, we developed a PCR-based assay kit for identification of Chinese mink tissues from 10 animal species in meat products, and to evaluate its quality indices including specificity, stability, sensitivity, and repeatability. Kits were made up of DNA extraction and PCR amplification systems based on species-specific, and universal primers. The reference meat mixtures and commercial samples were extracted by the kit and PCR technique was performed to identify the species of mink authenticity. The kit was effective after 20 repeated freeze-thaw cycles and it could be stored at -20 °C for 1 year. The sensitivity showed that a concentration as low as 0.1 ng/μL still can amplify the target band. The specificity test confirmed that the kit was 100% specific. The kit proved to be effective, stable, and reliable for extraction of efficient contents of the genomic DNA and routine analysis of Chinese mink source composition from meat products.

Development and validation of an undergraduate laboratory activity exploring the dna analysis of pet food

A novel experiment has been developed with a goal of enhancing engagement and deepening understanding of fundamental molecular biology concepts. In this laboratory activity, students investigate the composition of pet foods through quantitative polymerase chain reaction (qPCR) analysis. By conducting this experiment, students address a scientific question that has the potential to be of personal interest and they gain an appreciation of the power of genetic analysis. To develop this activity, ingredient lists of popular pet foods were surveyed and eight different components were selected to be the subject of inquiry. Reaction conditions for qPCR were validated and optimized, and a simple, efficient, and student-friendly protocol was developed. A cohort of upper-level biology students extracted DNA from pet foods and conducted the qPCR reactions. Specificity of amplification was determined by conducting melting point analysis and agarose gel electrophoresis of the products. Student reactions were analyzed and efficacy of this approach for deepening understanding of fundamental biochemical and molecular biology concepts was documented. © 2018 International Union of Biochemistry and Molecular Biology, 46(5):536-546, 2018.