CHARACTERIZATION OF PULLULANS PRODUCED FROM AGROINDUSTRIAL WASTES

Pullulans produced from the Aureobasidium pullulans fermentation of various agro-industrial wastes were characterised in terms of carbohydrate analysis, heterogeneity and molecular weights. Grape skin pulp extract (GSPE), starch waste (SW), olive oil waste effluents (OW) and molasses (M) were used as substrates for the production of pullulan. A glucose based defined medium (D) was used for comparison purposes. Weight average molecular weights were determined using size exclusion chromatography/multiangle laser light scattering. In each of the ethanol precipitated substances the molecular weights were higher than that of the reference pullulan (Sigma), and the elution profiles indicated the polydisperse nature of the pullulans. When using D, the molecular weight of pullulan produced decreased with increasing fermentation time. Different substrates produced pullulans with different molecular weights. Of the substrates studied, D, GSPE and SW produced pullulans in high yields, which were relatively homogeneous, while OW alone or with M produced greatly heterogeneous ethanol agglutinating substances.