Wheat straw hemicellulose films as affected by citric acid

Azeredo H. M. C., Kontou-Vrettou C., Moates G. K., Wellner N., Cross K., Pereira P. H. F., Waldron K.. (2015)

Food Hydrocolloids, 50, 1-6

Hemicelluloses have been extracted from wheat straw with an alkaline peroxide solution. Biodegradable films intended for food packaging have been produced from hemicelluloses mixed with glycerol and different concentrations of citric acid (as a crosslinking agent), with or without sodium hypophosphite (catalyst to the crosslinking reaction). A curing treatment at 150°C has been carried out on the dried films in order to promote formation of ester bonds between citric acid (CA) and hemicelluloses. The crosslinking reaction, evidenced by FTIR spectra, improved water resistance and water vapor barrier properties of the films. On the other hand, the CA effects on film tensile properties - reducing strength and modulus while increasing elongation - were more consistent with those of a plasticizer than of a crosslinker. Sodium hypophosphite (SHP) did not affect the properties of crosslinked films. FTIR spectra indicated that some crosslinking reaction occurred even in a non-cured film.

Food Hydrocolloids, 50, 1-6

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