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This paper (open access) reports the development of a label-free electrochemical immunosensor for the detection of low quantities of porcine gelatin.  The sensor is based on a boron-doped diamond electrode modified with aryl diazonium salt. The diazonium electrografting enabled stable covalent immobilization of anti-porcine gelatin antibodies via protein A, preserving anti­body orientation and activity.

The optimised conditions were a 500× antibody concentration, 60 minute antibody incubation, and 15 minute gelatin incubation. Detection was performed using differential pulse voltammetry with [Fe(CN)₆]3-/4- as a redox probe, allowing label-free monitoring of anti­body-antigen interactions based on changes in current.

The authors report that the immunosensor demonstrated excellent analytical performance, with a detection limit of 142.15 pg mL-1. Specificity testing showed no cross-reactivity with bovine gelatin.

Although suitable validation would be required, the authors conclude that this immunosensor has potential to form the basis of a rapid, highly sensitive, and specific platform for porcine gelatin detection, offering great potential for food authentication and halal verification.

Differentiating gelatin species is an analytical challenge because of a lack of intact DNA.  Most speciation methods therefore target the profile of proteins.  Proteins are difficult to analyse - they are too large to measure directly by techniques such as LC-MS, without  prior breaking down, and their folded structure is also an important diagnostic parameter.  This structure is disrupted by many of the sampling and extraction procedures used in analytical method. Analysis of mixed gelatins is particularly difficult.

This method (open access) used a new approach based on the interaction of ethanol with amino acids inside a protein. Ethanol can denature globular proteins by disrupting intraprotein hydrogen bonds due to hydrophobic interactions. However, when added to solutions having proteins with considerable number of α-helices, ethanol can stabilize the protein structure and prevent aggregation. The specific effects of ethanol on protein structure and function can vary depending on the protein's composition and environment.

Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to leverage ethanol's differential effects on gelatin's amide bands for quantifying pork gelatin contamination in bovine gelatin.

The authors report that the method showed a strong linear correlation between contamination levels and amide band transmission, with detection and quantification limits of 0.85 and 2.85 mg/100 mg (pork in bovine), respectively. It effectively identified pork gelatin in halal candy, with recovery rates from 50.05 % to 103.69 %.