Hydrolysis of cassava starch, chitosan and their mixtures in pressurized hot water media

Starch and chitosan widely available in food and food by-products can be converted by hydrolytic depolymerization into smaller compounds, like low molecular weight starch and chitosan. The objective of this study was to understand the effect of pressure and temperature on reaction mechanisms of cassava starch, chitosan and their mixtures in pressurized hot water media. A factorial design, including temperature, pressure and chitosan/starch ratios were investigated. A maximum amylose production of 27.1% from cassava starch was obtained at 75 degrees C and 155 bar. The highest depolymerization was observed at 150 degrees C for all pressures investigated. In addition, the increase of zeta potential (-3 to - 4 mV) to 2.11 mV after mixing starch with chitosan demonstrated the cross-linking of starch with chitosan via electrostatic interaction. Therefore, pressurized hot water processing is a potential green technology for low molecular weight biopolymer production, promoting reactions between starch and chitosan.