Prediction of Carbohydrate-Protein Interaction in Cassava Starch-Casein Blended Edible Films

Abstract

The aim of this research was to study protein-carbohydrate interaction in edible films. Edible films were made from a blend of cassava starch and casein. Tensile Strength (TS), percentage elongation (%E) and Solubility (S) were observed to study their inter-relationships. Fourier Transform Infra Red (FTIR) Spectroscopy was used to monitor the molecular interactions. Interaction of carbohydrate and protein was studied at pH of 4, 7 and 9 and various casein percentages (0, 20, 40, 60, 80 and 100%, respectively). Increasing the casein ratio decreased %E and S but improved TS. Improving the %E decreased the TS and S when pH was increased (p<0.05). FTIR spectra of the samples at 100% cassava showed there were changes in intensity at 3400-3600 cm -1 with the changes in pH and the lowest occured at pH 7. FTIR spectra of 100% casein films showed that intensity was increased by increasing the pH and the lowest intensity was at pH 4. The FTIR spectra of films from a blend of cassava starch-casein showed an absorbtion band similar to cassava starch films in the range 1200-1000 cm -1 and similar to casein films in the range 1700-1500 cm -1 . Highest interaction between cassava starch and casein molecules occurred at pH 9 in all cases. At 3600-2800 cm -1 it was the 60% casein films. In the region 1700-1500 cm -1 it was the 80% casein films and in the range 1200-1000 cm -1 was the 20% casein films. Presumable optimum interaction of carbohydrate-protein occurred at pH 9.