Preparation of Biodegradable Plastic Films from Tuber and Root Starches

Abstract

Starches were isolated from Irish potato, cocoyam and cassava tubers and were modified by chemically treating the native starches with Hydrochloric Acid (HCl). Proximate analysis and functional properties test namely, moisture content, protein content, crude fat content, ash content, crude fiber content, pH value, bulk densities (loose and packed), amylase and amylopectin were carried out on the native and modified starches. X-ray diffraction analysis of both the native and the modified starches were carried out. From the X- ray diffraction, Miller indices, particle size and the degree of crystallinity were calculated. The native and modified starches were then used to prepared plastic film. The mechanical properties, namely, tensile strain, tensile stress, and young modulus were calculated from the mechanical properties data, which were obtained from the Instron 3369 mechanical testing machine. Proximate analysis and functional properties test result show that the three tuber starches isolated have low non-starch component which make them a good raw materials for plastic film. X-ray diffraction of both native potato and cassava starches gives degree of crystallinity of 20.6% whereas X-ray diffraction of modified native and potato has degree of crystallinity of 41.7% and 44.3% crystallinity respectively. The increase in degree of crystallinity of modified starches may due to the breaking down of amylopectin to amylose.The mechanical properties of the films improved when the starches were modified. The results showed that the selected tuber root starches are beneficial and capable of replacing the popular synthetic plastic materials that are not