A mass spectrometry method for the determination of the species of origin of gelatine in foods and pharmaceutical products

Advances and key considerations of liquid chromatography–mass spectrometry for porcine authentication in halal analysis

The halal food industries are rapidly expanding to fulfill global halal demands. Non-halal substances such as porcine proteins are often added intentionally or unintentionally to products. The development of highly selective and sensitive analytical tools is necessary, and liquid chromatography–mass spectrometry is a powerful tool that can cope with the challenge. The LC–MS method has great potential for halal authentication, because it has high sensitivity and low detection limit and detects several species markers and different tissue origins at once within one species. This article provides an understanding of recent advances in the application of LC–MS for the improvement of porcine authentication. Sample preparation, marker selection, separation and mass spectrometry conditions, quantitative assessment, and data processing for protein identification were all covered in detail to choose the most suitable method for the analytical needs.

A qualitative peptide biomarker approach to identify piscine gelatine in products to support food security

Due to allergy concerns, it is mandatory under EU law to declare in food products all ingredients derived from fish. Gelatine is prepared from the waste collagen of animal carcasses, including piscine, bovine and porcine materials, and is an ingredient in a wide range of foods. The Elliott Review into the integrity and assurance of food supply networks highlighted requirements for analytical surveillance methods to support due diligence, food safety and authenticity. We present the development of a method to extract gelatine from foods and determine the presence of piscine gelatine by liquid chromatography-tandem mass spectrometry using a suite of sixteen piscine marker peptides. The method has been successfully applied to gelatine granules, capsules and composite retail food products. While a study is required to determine parameters including the limit of detection of this method, the data indicate the method is reproducible between replicates of sub-samples and applies to a range of piscine gelatines collected over 16 years. Once validation studies are complete, there is potential for enforcement officers to apply the technology to verify the authenticity of fish products to support consumers in ensuring food safety and also food provenance relating to animal origin.

The quest for a generic bird target to detect the presence of bird in food products and considerations for paleoprotein analysis

It can be important for consumers to know whether food products contain animal material and, if so, of which species. Food products with animal material as an ingredient often contain collagen type 1. LC-MS/MS (Liquid Chromatography-tandem Mass Spectrometry) was applied as technique to generically detect bird. Unlike for example fish, that have experienced longer divergence times, it is still possible to find generic LC-MS targets for avian type 1 collagen. After theoretical target selection using 83 collagen 1α2 bird sequences of 33 orders and construction of a common ancestor sequence of birds, experimental evidence was provided by analyzing extracts from 10 extant bird species. Two suitable options have been identified. The combination of VGPIGPAGNR and VGPIGAAGNR (pheasant only) covers all investigated birds and was not found in other species. The peptide EGPVGFpGADGR covers all investigated birds, but also occurs in several species of crocodiles and turtles. The presence of the generic peptide (combination) was confirmed in food products, proving the principle, and can therefore be used to detect the presence of bird. Furthermore, it is shown how the use of constructed ancestor sequences could benefit the field of paleoproteomics, in the interpretation of collagen MS/MS spectra of ancient species. Our theoretical analysis and assessment of reported Brachylophosaurus canadensis collagen 1α2 MS/MS data provided support for several previous peptide sequence assignments, but we also propose that our constructed ancestral bird sequence GPpGESGAVGPAGPIGSR may fit the MS/MS data better than the original assignment GLPGESGAVGPAGPpGSR.

Solidification of Gelatine Hydrogels by Using a Cryoplatform and Its Validation through CFD Approaches

In this work, we developed a numerical approach based on an experimental platform to determine the working conditions on a cryoplatform and to predict and evaluate the cryogenic printing of hydrogels. Although hydrogels have good biocompatibility, their material properties make it difficult to print them with high precision and shape fidelity. To overcome these problems, a cryogenic cooling platform was introduced to accelerate the physical stabilisation of each deposited layer during the printing process. By precisely controlling solidification (crystallisation), each printed material can withstand its own weight to maintain shape fidelity, and the porosity of the scaffolds can also be controlled more selectively. The thermophysical properties of gelatine hydrogels were investigated to gain a better understanding of the phase change upon freezing. The corresponding material properties and experimental observations of gelatine solidification served as the basis for developing a computational fluid model (CFD) to mimic the solidification of gelatine hydrogels using a cryoplatform at different process conditions and extruder speeds. The goal was to develop a tool simple enough to predict acceptable process conditions for printing gelatine hydrogels using a cryoplatform.

Rapid analysis to distinguish porcine and bovine gelatin using PANI/NiO nanoparticles modified Quartz Crystal Microbalance (QCM) sensor

Rapid analysis to distinguish porcine and bovine gelatin using a modified Quartz Crystal Microbalance (QCM) sensor has been studied. The PANI was deposited on the sensor surface using electropolymerization, and then nickel nanoparticles were deposited by layer by layer (LbL) technique. The modified QCM sensor's performance was compared to an unmodified sensor in porcine and bovine gelatin at neutral, acidic, and alkaline conditions. The result shows that the unmodified sensor cannot distinguish between porcine and bovine gelatin, whereas the modified QCM sensor produces a different response. Porcine gelatin shows an increasing frequency response, but in contrast, bovine gelatin decreases frequency response at the alkaline condition. The time response was 2 min with a detection limit of 51.2 ppm and 8.7 ppm for porcine and bovine gelatin, respectively. Further investigation shows that the modified sensor can analyze porcine gelatin contamination in the a mixed gelatin sample.

Determination of clenbuterol at trace levels in raw gelatin powder and jellies using ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry

Clenbuterol is present in animal tissues and organs and, therefore, potentially present in gelatin derived from animal sources. The objective of this study was to develop a method for identify an quantify traces of clenbuterol in gelatin and jellies. The clenbuterol calibration curve showed linearity in the range of 20-1000 pg mL^-1. The detection and quantification limits were 5 pg g^-1 and 10 pg g^-1, respectively. The recovery of the analyte ranged from 93.4 to 98.7% with an intra-day RSD% (n = 4) of 1.25%-3.25%, and an inter-day RSD% (n = 12) of 0.5%-2.25%, with good linearity (R² = 0.99). The method developed and validated was successfully applied in 54 gelatin samples, 57.4% of which showed clenbuterol. This UHPLC-MS/MS method combines high sensitivity with good selectivity and short chromatographic run time.

Development of a two-level control system for the analysis of the composition of meat products

Because of the increased demand for processed meat, there is an urgent need to introduce specific identification methods. Strategies such as molecular genetics and the physical condition of meat are used to quickly explore multi-component products. However, a single methodology does not always unambiguously classify a product as counterfeit. In laboratory practice, as a rule, screening techniques are rarely used in the first stage, followed by arbitration. This work aimed to study individual methodologies using artificially falsified meat samples as examples and to identify their composition based on muscle tissue. For the experiments, the three most common types of raw meat were selected: pork, beef, and chicken. The calculation of the content of muscle tissue was carried out according to the BEFFE method. The study of muscle protein was carried out by ICA, ELISA, PCR, microstructural analysis, and mass spectrometric identification. In this connection, we proposed a multilevel control system for multicomponent meat products. Both classical methodologies, such as calculation by prescription bookmarks (BEFFE) and microstructural analysis, and approaches of highly sensitive methodologies, such as identification of muscle tissue by marker peptides (LC/MS-MRM) and semi-quantitative PCR analysis, were evaluated.

Mass spectrometry-based protein and peptide profiling for food frauds, traceability and authenticity assessment

The ever-growing use of mass spectrometry (MS) methodologies in food authentication and traceability originates from their unrivalled specificity, accuracy and sensitivity. Such features are crucial for setting up analytical strategies for detecting food frauds and adulterations by monitoring selected components within food matrices. Among MS approaches, protein and peptide profiling has become increasingly consolidated. This review explores the current knowledge on recent MS techniques using protein and peptide biomarkers for assessing food traceability and authenticity, with a specific focus on their use for unmasking potential frauds and adulterations. We provide a survey of the current state-of-the-art instrumentation including the most reliable and sensitive acquisition modes highlighting advantages and limitations. Finally, we summarize the recent applications of MS to protein/peptide analyses in food matrices and examine their potential in ensuring the quality of agro-food products.

Gene expression of microbial gelatinase activity for porcine gelatine identification

In order to invent a porcine gelatine detection device using microbial resources, bacterial enzymes with a preference towards porcine gelatine and their candidate genes were evaluated. Five (n = 5) bacterial strains isolated from hot spring water and wet clay, Malaysia were screened for their gelatinase activity. The gelatinase enzyme was extracted and purified using ammonium sulphate precipitation prior to performing gelatinase assay on porcine, bovine and fish gelatine medium substrates. The G2 strain or Enterobacter aerogenes (Strain EA1) was selected for whole genome sequenced after showing a consistent trend of preference towards porcine gelatine. The gelatinase candidate gene gelEA1_9 was cloned and expressed. Based on one-way analysis of variance (ANOVA) with POST-HOC Duncan test (α = 0.05), the final product of gelEA1_9 was identified as a novel gelatinase. This gelatinase presented no significant difference in activity towards porcine gelatine. Hence, the present study demonstrated an enzyme-substrate interaction for porcine gelatine identification.

Development and verification of a quantitative real-time PCR method to identify and quantify gelatin derived from animal hide

The species origin of hide gelatin is a crucial issue with respect to health concerns and religious restrictions. Analysis of the animal-derived ingredients of gelatin by reliable methods is necessary to ensure its authenticity. However, due to the highly processed nature of gelatin, it remains a challenge to identify gelatin end products accurately and robustly. Our study established and verified a quantitative real-time PCR (qPCR) method based on careful selection of target genes and a DNA extraction method. The middle products of the gelatin production streamline were investigated to explore the influence of each critical processing step on the method. Gelatin reference samples were used to quantify the levels of target species. Commercial gelatin commodities were surveyed to highlight the mislabeling situation. In summary, the qPCR method was demonstrated to be highly specific and sensitive, with limits of detection (LOD) of 0.1 to 1 pg/µL and gelatin LODs of 0.1% to 5% (w/w). The transition from decoction to concentrated gel was found to have the most severe effect on the qPCR. Intensification of pressure or temperature or employment of enzyme hydrolysis aggravated the DNA damage, resulting in elevated Cq values. Quantitation of gelatin products was feasible; gelatin products produced from 5% target hide and 95% matrix hide mixtures showed 2.9% to 5.2% target species. The 26% relative error for low gelatin content is acceptable for semiquantitation purposes. A market survey showed that 52.6% of the gelatin products were mislabeled as being of animal origin.

Collagen analysis with mass spectrometry

Mass spectrometry-based techniques can be applied to investigate collagen with respect to identification, quantification, supramolecular organization, and various post-translational modifications. The continuous interest in collagen research has led to a shift from techniques to analyze the physical characteristics of collagen to methods to study collagen abundance and modifications. In this review, we illustrate the potential of mass spectrometry for in-depth analyses of collagen.

Effects of γ-polyglutamic acid on the gelling properties and non-covalent interactions of fish gelatin

The effects of γ-polyglutamic aid (γ-PGA) on the gelling properties and non-covalent interactions of fish gelatin were investigated. The gel strength and melting temperature of fish gelatin gradually increased, with increasing γ-PGA concentration, although there was no significant change when the γ-PGA concentration was greater than 0.04%. As the concentration of γ-PGA increased, the electrostatic interaction of fish gelatin increased and the hydrophobic interaction between gelatin molecules decreased. The fish gelatin system was comprised of γ-PGA concentrations of 0.04 and 0.06% showing a strong hydrogen bond. When the γ-PGA concentration increased from 0 to 0.04%, more phenolic hydroxyl groups in the tyrosine residue tended to form hydrogen bonds with the protein. However, an additional increase in γ-PGA concentration to 0.1% led to enhanced hydrogen bonding with water molecules. The results of this study showed that hydrogen bonds played an important role in improving the gelling properties of gelatin by γ-PGA.

Tannic Acid: a Novel Calibrator for Facile and Accurate Mass Measurement of Electrospray Ionization Mass Spectrometry

Accurate mass calibration is beneficial to the identification of the unknown compounds quickly and accurately. The ESI mass spectrum of tannic acid (TA) tends to a normal distribution of the cluster ion peaks in m/z range from 371.0368 to 1739.1169. Based on the interesting result, we reported the use of TA, a natural plant polyphenol, as a novel calibrator for electrospray ionization mass spectrometry (ESI MS), which has the following three advantages, including (1) easy preparation, (2) the calibration range of m/z 200~2000, and (3) the calibration error is around 3.00 ppm in positive ion mode, which is less than the use of sodium formate (SF) and Prod #88323 calibrators. This TA calibrator has great potential for the wide applications in biological, chemical, and pharmacal analysis.

A Review of Gelatin Source Authentication Methods

Gelatin is a very popular pharmaceutical and food ingredient and the most studied ingredient in Halal researches. Interest in source gelatin authentication is based on religious and cultural beliefs, food fraud prevention and health issues. Seven gelatin authentication methods that have been developed include: nucleic acid based, immunochemical, electrophoretic analysis, spectroscopic, mass-spectrometric, chromatographic-chemometric and chemisorption methods. These methods are time consuming, and require capital intensive equipment with huge running cost. Reliability of gelatin authentication methods is challenged mostly by transformation of gelatin during processing and close similarities among gelatin structures. This review concisely presents findings and challenges in this research area and suggests needs for more researches on development of rapid authentication method and process-transformed gelatins.

Rapid detection of collagens using a closed-tube LAMP method

Identification methods of collagens and gelatins have been studied many years due to religious and food safety issues. Some researchers detected the collagen while others took up their study based on DNA at the first time. In this work, we used a closed-tube loop-mediated isothermal amplification (LAMP) technique to differentiate collagen and gelatin samples. DNA was extracted by DNeasy mericon Food Kit and was dissolved in 30 µl elution buffer, optimum concentration of Mg²⁺, deoxyribonucleoside triphosphates(dNTPs), betaine in LAMP reaction is 6.0 mmol/L, 2.0 mmol/L, and 0.8 mmol/L, respectively. After LAMP reaction, samples being detected changed their initial color to green, others' were colorless or brown slightly. The research offered a simple, fast detection technique to differentiate collagen and gelatin samples derived from porcine, bovine and channel catfish (Ictalurus punctatus) , the collagens' species can be determined by color variation in reaction tubes within two hour.

A rapid and simple UPLC-MS/MS method using collagen marker peptides for identification of porcine gelatin

Gelatin, which is mainly derived from bovine and porcine sources, has been used in many foods and pharmaceutical products. To ensure the compliance of food products with halal regulations, reliable analytical methods are very much required. In this study, one unique marker peptide for porcine gelatins was selected to develop an UPLC-MS/MS multiple reaction monitoring method. The capability of this method to identify porcine materials was demonstrated by analyzing in-house-made gelatins containing different amounts of porcine gelatins and commercial gelatin products. The adulteration of porcine gelatin could be sensitively detected at a low level of 0.04%. When combined with HPLC and mass spectrometry, this method is an accurate and sensitive quantitative method to identify porcine gelatins. Thus, the strategy can be used to verify halal authenticity of gelatin.

Gelatin, which is mainly derived from bovine and porcine sources, has been used in many foods and pharmaceutical products.

Simultaneous detection of bovine and porcine DNA in pharmaceutical gelatin capsules by duplex PCR assay for Halal authentication

Background

In the pharmaceutical industry, hard- and soft-shelled capsules are typically made from gelatin, commonly derived from bovine and porcine sources. To ensure that pharmaceutical products comply with halal regulations in Muslim countries (no porcine products allowed), development of a valid, reliable, quick, and most importantly, cost-effective tests are of utmost importance.

Methods

We developed a species-specific duplex polymerase chain reaction (PCR) assay targeting 149 bp porcine and 271 bp bovine mitochondrial DNA (mtDNA) to simultaneously detect both porcine and bovine DNA (in one reaction at the same time) in gelatin. Some additional simplex PCR tests (targeting 126 bp bovine and 212 bp porcine mtDNA) and real-time PCR using a commercially available kit (for identification of porcine DNA) were used to verify the selectivity and sensitivity of our duplex PCR. After optimization of DNA extraction and PCR methods, hard/soft pharmaceutical gelatin capsules (containing drug) were tested for the presence of porcine and/or bovine DNA.

Results

Duplex PCR detected the presence of as little as 0.1% porcine DNA, which was more accurate than the commercially available kit. Of all gelatin capsules tested (n = 24), 50% contained porcine DNA (pure porcine gelatin alone or in combination with bovine gelatin).

Conclusions

Duplex PCR presents an easy-to-follow, quick, low-cost and reliable method to simultaneously detect porcine and bovine DNAs (>100 bp) in minute amounts in highly processed gelatin-containing pharmaceutical products (with a 0.1% sensitivity for porcine DNA) which may be used for halal authentication.

Graphical abstract

Simultaneous detection of porcine and bovine DNA in gelatin capsules by duplex PCR