Influence of the Presence of Chemical Additives on the Thermal Properties of Starch

Abstract

Starch is an essential but very complex semi-crystalline biopolymer. In addition to being an important food source, numerous industrial applications have been proposed for this renewable material. Most applications are highly dependent on the physical properties of the material which are a strong function of the amount of intra- and inter-molecular interactions. This research investigates the potential to manipulate the type and amount of chain-chain interactions to tailor the properties of starch for different applications. Three types of additives acting as probe molecules were used to vary these interactions by changing the amounts and the pH of each sample: a very polar organic molecule, glycerol, a high electron density compound, TiO2, and a mostly hydrophobic organic molecule, cholesterol. Differential scanning calorimetry was used to determine the strength and the amount of chain-chain interactions while Fourier transform infrared spectroscopy was used to follow the nature of these interactions. Results show that the different probe molecules do interact with starch but form chemical interactions at different locations on the chain. We conclude that with proper play on amount, type of additive, temperature cycle, and pH a composite of starch could be tailored for numerous and specific applications.