Preparation and evaluation of hemicellulose films and their blends

Abstract

Cell wall hemicelluloses are useful in various industries due to their ability to form edible and biodegradable films with plasticizers such as glycerol. The objective of this research was to extract hemicelluloses from Caesalpina pulcherrima and Tamarindus indica, produce film blends from them, and evaluate their properties and their product development potential. The extraction process provided yields of 25% galactomannan (GalCp) from C. pulcherrima and 20% xyloglucan (XilTi) from T. indica. The apparent Mw obtained by GPC were 4.35 × 106 g/mol and 2.03 × 106 g/mol for GalCp and XilTi respectively. The ratio of mannose/galactose in GalCp determined by 13C NMR was (2: 1), while the ratio of glucose/xylose/galactose in XilTi obtained by 13C NMR was (1.0: 1.2: 1.0). All filmogenic solutions from these hemicelluloses showed non-Newtonian rheological behavior at 25 °C. The IR spectra were consistent with the presence of GalCp and XilTi and were fully assigned. Galactomannan film exhibited a higher permeability to moisture than xyloglucan and the blends. All films showed less than 20% opacity; thus, they were relatively transparent. Thermogravimetric analysis indicated that the blend films had good thermal stability. The use of these blends permits a wider range of properties to be obtained than the hemicelluloses alone. Thus, these materials may serve as useful biodegradable and environmentally friendly materials for food packaging applications.