The microheater: A new tool for rapid determination of food kinetics

The microheater is a novel heat exchanger that is made in quartz, which has been developed to speed up process and product design through faster screening. Industrial time¿temperature profiles can be mimicked, while the measurement time is short and sample volumes required are very small. The first step undertaken was validation of the microheater, using off-line turbidity measurements. As a model system, denaturation/aggregation kinetics of whey protein isolate (WPI) was investigated. The microheater operates at overall heat transfer coefficients of 600¿1000 W m¿2 K¿1, and it enabled to distinguish between different kinetic models at a given temperature. In addition, the temperature dependency of the kinetics was also investigated; a typical value would be an Arrhenius constant of around 100 kJ mol¿1 K¿1 for the observed changes in turbidity. Finally, an in-line measurement cell was added to the set-up to allow continuous measurement of the turbidity. Promising results were obtained with this set-up, which indicate that faster measurements are within reach, and with this, process and product development can become considerably less time-consuming.