Development of a real-time PCR assay for the detection of cow and donkey milk

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.

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.

Detection of ovine milk adulteration using taqman real-time pcr assay

Food safety, quality and composition have become the subjects of increasing public concern. To prevent fraud and enhance quality assurance, credible analysis of dairy products is crucial. Bovine milk is more widely available and cheaper than milk of sheep and goat. Bovine milk is also processed in large quantities to produce a range of dairy produce. DNA-based methods have proven to be more reliable, because of the stability of DNA under the conditions of high temperature, high pressure, and chemical treatment used during the processing of some food products. The commercial InnuDETECT cheese assay based on the principle TaqMan real-time PCR systems have been tested for the identification and quantification of bovine DNA in ovine milk samples. DNA was extracted using the InnuPREP DNA Mini Kit and quantified by the QuantiFluor dsDNA system. The assay showed good linearity, with correlation coefficient of R2 = 0.983 and efficiency of 86%. The internal control amplified fragment from different mammalian species (cow, sheep and goat), with similar CT values. Detection of bovine DNA in milk mixtures was achieved even in samples containing 0.5% of bovine milk. The InnuDETECT cheese assay has been successfully used to measure bovine DNA in ovine milk, and will prove useful for bovine species identification and quantitative authentication of animal-derived products.

Methodologies for the Characterization of the Quality of Dairy Products

The growing interest of consumers in food quality and safety issues has contributed to the increasing demand for sensitive and rapid analytical technologies. Physicochemical, textural, sensory, etc., methods have been used to evaluate the quality and authenticity of milk and dairy products. Despite the importance of these standard methods, they are expensive and time consuming. Recently, spectroscopic methods have shown great potential due to speed of analysis, minimal sample preparation, high repeatability, low cost, and, most of all, the fact that these techniques are noninvasive and nondestructive and, therefore, could be applied to any on-line monitoring system. This chapter gave examples of the application of the most commonly traditional methods for the determination of the quality of milk and dairy products. A special focus is devoted to the use of infrared and fluorescence spectroscopies for the evaluation of the quality of dairy products.

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

Fast real-time PCR TaqMan assays were developed and validated for species identification in dairy products. Based on the amplification of 12S rRNA and cytB partial genes of mitochondrial DNA, the methods were demonstrated to be sensitive, fast, and species-specific for Bos taurus, Ovis aries, Bubalus bubalis, and Capra hircus. The limit of detection calculated was lower than 1%, and the efficiency was reported to be higher than 96% in every assay. An internal amplification control was used to detect possible false negatives. The method was validated by means of laboratory-prepared samples mixing different species. Moreover, 18 commercial dairy samples were analyzed by both real-time PCR and isoelectric focusing, the official European Union reference method. The 4 TaqMan assays were confirmed to be a useful tool for milk and dairy product authentication.