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Reactions between β-Lactoglobulin and Genipin: Kinetics and Characterization of the Products

Author:
Qi, Phoebe X., Nuñez, Alberto, Wickham, Edward D.
Source:
Journal of agricultural and food chemistry 2012 v.60 no.17 pp. 4327
ISSN:
0021-8561
Subject:
activation energy, atomic force microscopy, beta-lactoglobulin, crosslinking, desorption, mass spectrometry, pH, polyacrylamide gel electrophoresis, reaction kinetics, temperature
Abstract:
In this paper, we present the first detailed study of the reaction kinetics and the characterization of the products from the endothermic reactions between β-lactoglobulin and genipin. The effects of the concentration, temperature, and pH were investigated. In the temperature range studied, the reaction was approximately a pseudo-first-order with respect to genipin and 0.22-order and −0.24-order with respect to β-lactoglobulin for pH 6.75 and 10.5 with corresponding activation energy (Ea) estimated to be 66.2 +/- 3.8 and 9.40 +/- 0.36 kJ/mol, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis studies, validated by matrix-assisted laser desorption ionization-time of flight mass spectrometry, showed the presence of oligomeric, i.e., di-, tri-, quadri-, and pentameric, forms of cross-linked β-lactoglobulin by genipin at neutral but not alkaline pH; however, an extensive cross-linked network was not observed, consistent with the atomic force microscopy images. It was demonstrated that the reaction temperature and the concentration of genipin but not that of β-lactoglobulin positively affected the extent of the cross-linking reactions.
Agid:
60520
Handle:
10113/60520