Emulsifying Properties of Hemicelluloses

This chapter focuses on the emulsifying properties of hemicelluloses. Hemicelluloses are gummy polysaccharides of complexity between gum and cellulose. Based on the major monosaccharide constituents of their backbone, hemicelluloses can be classified into xylans, mannans, xylogalactans and xyloglucans. Their sources include seeds, husks, straws, leaves and wood. Hemicelluloses bring about emulsification by viscosity modification and by formation of multilayered films around each globule of the dispersed phase. They have strong emulsifying power but are somehow limited by batch-to-batch variation and susceptibility to microbial and chemical degradations. These limitations are overcome by the use of purified and semisynthetic derivatives. Hemicelluloses and derivatives herein considered for their emulsifying properties include those from barley straw, wheat straw, corn fiber, locust bean, guar, soy bean, konjac, prosopis seed and afzelia seed. Hemicelluloses, as plant polysaccharides, are only second to cellulose in terms of abundance. They have superior emulsifying properties compared to the typical gums. They are amenable to many chemical modifications for the enhancement of stability and for the improvement of emulsifying properties. Hemicelluloses were not given adequate attention in the past; but this chapter shows that they are potentially useful emulsifying agents.