A turbidimetric study of phase separating biopolymer mixtures during thermal ramping

A method for particle sizing using a commercial spectrophotometer is presen ted, based on a Rayleigh-Gans-Debye treatment of the wavelength dependence of turbidity. The finite acceptance angle of the spectrophotometer has been taken into account and shown to be potentially advantageous. The method ha s been used to monitor the kinetics of droplet growth in phase separating b iopolymer mixtures of gelatin and maltodextrin, and predicted droplet sizes have been compared with data obtained from confocal laser scanning microsc opy. Furthermore, the temperature dependence of the turbidity data is used to construct a model of the phase behavior of the biopolymer mixture. For s ystems demixing between 60 and 30 degrees C, the driving force for phase se paration is solely governed by the temperature-dependence of the Flory-Hugg ins interaction parameters. Below 30 degrees C the gelatin ordering trigger s additional driving forces for phase separation and subsequently leads to the formation of a gel network that traps the system microstructure.