Preparation, characterization and stability of nanogels made with reticulated casein micelle
Résumé
Modifications of casein micelles (CMs) by technological treatments and/or addition of biochemical reagents constitute a scientific challenge to create new structures and functionalities. In this work, modification of CMs by a natural cross-linker, named genipin (GP), was performed and their new physico-chemical properties and stabilities were appreciated. The reaction between GP and CMs was characterized by formation of blue pigmented products, presenting a maximum absorption at ~600 nm. The RP-HPLC and SDS-PAGE analyses of CMs-GP showed that casein molecules were cross-linked mainly via lysyl residues. The zeta potential of CMs -GP was reduced, indicating changes in their surface properties. The analyses of the size distribution revealed no major changes regarding the average diameter and shape of the CMs-GP. Stable crosslinking was demonstrated by submitting the CMs-GP to dissociation conditions. By atomic force microscopy, the dimensional characteristics of CMs-GP revealed that contact angle were different compared to native CMs. Moreover, it was confirmed that CMs-GP were stable at pH 5.2 or in the presence of citrate in spite of their demineralization. Further researches are necessary to elucidate the modifications in their internal structure and the consequences in their functional properties, like gels, emulsions and foams