Structural and physicochemical characteristics of starch from sugar cane and sweet sorghum stalks

The starch present in sugar cane and sorghum juice has been considered a problem to the sugar industry. The objective of this work was to study the structural and physicochemical characteristics of the starch present in sugar cane and sweet sorghum. Sugar cane and sweet sorghum starches presented small granules (maximum 5.9 and 7.9 μm), A-type diffraction pattern, high degree of relative crystallinity (44.4 and 42.0%), and low amylose content (17.5 and 16.4%), respectively. Sugar cane starch presented more uniformity in granule shape and size, more homogeneity in amylose chain length, higher number of long lateral chains of amylopectin, and higher susceptibility to enzymatic digestion. Besides being in higher amount in the juice, sweet sorghum starch presented lower values for thermal properties of gelatinization, as well as higher swelling factor, which can cause more problems during processing. Additional studies are needed to evaluate the variety and maturity influence on these properties.