Physical chemical study of zein and arabinogalactans or glucuronomannans polyelectrolyte complexes and their film-forming properties
2020
da Silva, Caroline E.P. | de Oliveira, Marco A.S. | Simas, Fernanda F. | Riegel-Vidotti, Izabel C.
Four gum exudates, the arabinogalactans gum Acacia (GA) and Acacia mearnsii gum (GN) and the glucuronomannans gum Ghatti (GG) and Vochysia thyrsoidea gum (VT) were used to obtain polyelectrolyte complexes (PECs) with zein, a corn protein. GA and GG are commercially available, whereas GN and VT are obtained from Brazilian trees. The polysaccharides differ in their monosaccharide composition and protein content. The PECs were prepared by desolvation or nanoprecipitation methods, therefore the type of gum and the preparation method were related to the PECs physical chemical properties and their film-forming characteristics. The higher yields of complexation were obtained by desolvation, which also lead to the larger aggregates due to the diffusion impairments inherent to this method. The different chemical properties of polysaccharides influenced the yielding of complexation. The spatial availability of uronic acid units contributed to make GG the best pair for zein, followed by VT, GN, and GA, according to the carbohydrate coacervation yield. Concerning the protein yield, PECs with GA retained more zein, followed by GG, GN, and VT. Despite all PECs presented good film-forming properties, the glucuronomannans formed the most homogeneous ones. The films surface energies were obtained by the Lifshitz-van der Waals/Lewis acid-base (LWAB) model, being possible to predict that these coatings would adhere more favorably to strawberry, independently of the polysaccharide used. Therefore, it was demonstrated that the polysaccharides extracted from A. mearnsii and V. thyrsoidea trees can be used in multicomponent edible coatings as their commercial analogues, respectively gum Arabic and gum Ghatti.
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