In the framework of the EMPIR Project 14IND11 HIT (Metrology for humidity at high
temperatures and transient conditions), a method for estimating in real time the water loss in a
hazelnuts roasting process, through humidity measurements, and its correlation with food quality
parameters was demonstrated in an industrial application.
At the industrial plant of a manufacturer of food processing systems, two separate measurement
setups were designed and implemented on laboratory-scale roasting ovens, based on infrared and
hot-air heating, in order to estimate both the water loss and the volume temperature distribution
in real time during roasting tuning processes. In such a roasting process, air temperature and dew
point temperature were associated with the detailed roasting protocol which in turns produces
different quality of the final processed product. To perform such in-process measurements, the
above quantities were measured by several PRTs and by a chilled-mirror hygrometer at
temperatures between 120 °C to 180 °C and dew-point temperatures up to 35 °C, respectively.
This work reports on the measurement set-up, the details about preventing volatile organic
contamination of the chilled-mirror hygrometer and the validation of real-time humidity
measurements by comparison against a gravimetric (water-loss) method. Suitable data
processing methods of humidity measurements were implemented in order to the estimate water
loss from dew-point measurements and correlate it with selected food-quality parameters. The
overall results of the study are presented
