Quantification of κ-casein in milk by an optical immunosensor

Abstract

k-casein (k-CN) plays an important role in the stability and coagulation properties of milk. An immunoassay to quantify k-casein in milk, using an optical biosensor based on surface plasmon resonance (SPR) measurement, has been developed. The assay consists of a two-step sandwich strategy, with two anti-k-casein antibodies directed against each extremity of the casein to quantify only native k-casein. The analysis time per sample was less than ten minutes. The antibody-coated surface could be used for more than 150 determinations. The detection limit was established at 0.45 mg.ml (1 and the intra-and inter-assay variation coefficients were 4.28% and 6.8%, respectively. The method was applied to raw milk in order to quantify intact k-casein, with no pretreatment of the sample. It also allowed the monitoring of k-CN concentration during milk coagulation after addition of rennet.

Milk Proteins: Analytical Methods

“…Biosensor technology has been used in food analysis since the mid-1990s. During the last years, SPR-based biosensors have been applied to milk proteins for quantifying caseins in milk (Muller-Renaud et al, 2005;Muller-Renaud et al, 2003;Muller-Renaud et al, 2004), following casein-casein (Marchesseau et al, 2002;Thompson et al, 2010) or casein-polysaccharides interactions (Thompson et al, 2010). Furthermore, Johansson et al examined the potential of SPR-based immunosensors used as probes for exploring the surface of the casein micelle (Johansson et al, 2009).…”

Rapid detection of mozzarella and feta cheese adulteration with cow milk through a silicon photonic immunosensor

“…Depending on the transducer used, biosensors are distinguished as electrochemical, piezoelectric and optical ones. [27][28][29][30][31] The latter offer several competitive advantages, such as signals that are less vulnerable to interference, since the detector is isolated from the sample, the potential of miniaturization and as a corollary the system compactness and portability as well as multianalyte detection schemes. Even more specifically, label-free immunosensors are suitable for real-time and on-site analysis, since they provide direct signal transduction and highthroughput screening.…”

Quantitative Estimation of Casein in Different Milk Samples

“…Casein is considered as a chief and major component of milk because it constitutes about 80% of milk protein [8,9] while remaining are lactose and whey [10]. The main casein components involve αS1-casein, αS2-casein, β-casein and κ-casein [8,10].…”