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Quantification of beta casein in milk and cheese using an optical immunosensor
Stéphanie Muller-Renaud1, Didier Dupont, Philippe Dulieu
1INRA, Unité de Recherches en Technologie et Analyses Laitières, Place du Champ de Foire, F-39800 Poligny, France.
Journal of Agricultural and Food Chemistry
|February 19, 2004
Summary
This study presents a rapid optical immunosensor for quantifying intact beta-casein in milk and cheese. The surface plasmon resonance (SPR) method accurately measures beta-casein, aiding in dairy product analysis.
Area of Science:
- Analytical Chemistry
- Food Science
- Biotechnology
Background:
- Accurate quantification of beta-casein is crucial for dairy product quality control and understanding cheese ripening.
- Existing methods may not distinguish between intact beta-casein and its degradation products.
Purpose of the Study:
- To develop and validate a rapid, sensitive optical immunosensor for quantifying intact beta-casein.
- To apply the method for analyzing raw milk and monitoring proteolysis during cheese ripening.
Main Methods:
- Utilized a two-step sandwich immunoassay with surface plasmon resonance (SPR) detection.
- Employed antibodies targeting both ends of beta-casein to ensure quantification of the intact protein.
- Validated the assay using a reference milk powder.
Main Results:
- Achieved a detection limit of 85 ng/mL with low intra- (2.6%) and inter-assay (6.2%) variation.
- Demonstrated rapid analysis time per sample (<10 minutes).
- Successfully quantified intact beta-casein in raw milk without pretreatment and monitored its degradation in cheese.
Conclusions:
- The developed SPR-based immunosensor is a reliable and efficient tool for quantifying intact beta-casein.
- The method enables direct analysis of raw milk and provides insights into cheese proteolysis.
- The reusable antibody-coated surface offers a cost-effective solution for routine analysis.