Control of infant dairy product spray drying by taking into consideration the water-constituents interactions
June 6, 2012 by Pierre Schuck
This study tried to predict the sticking sensitivity of dairy concentrates during spray drying. The characteristics of resulting powders were also presented. The modelling approach was based on the SD²P® - (Predicative software of spray drying parameters, INRA). The model was enhanced to integrate water-constituents interactions. The standardized desorption method was used and compared to a method called “glass filament”. Other data were also integrated, issued from the reaction engineering approach.
Spray drying is the most widely used technique for infant dairy food dehydration
A poorly managed drying process can lead to product non-conformity and substantial economic losses. The prediction method of key drying parameters, SD²P®, does not give information on the sticking sensitivity of the products obtained. This sticking phenomenon is related to the glass transition temperature. For solutions with high water amounts, a rapid determination of this characteristic in the concentrate is complex or impossible.
Considering the diversity and the complexity of infant formulas studied, a simple and reliable predication method of drying behavior of concentrates is needed.
The work, conducted by the INRA team, studied water transfer during drying process. The aim was to propose a method which could predict the drying behavior of infant milk products in order to control the drying operations. They developed the following strategy:
- Development of an estimating method of the glass transition temperature (Tg) of the concentrate under dry condition, in order to identify the caking sensitivity. And the development of a method using the divergence point to optimise drying parameters.
- Development of a desorption method called “glass filament” adapted to REA approach. This method combined with the SD²P® approach predicts product characteristics and behavior during the drying process.
A mathematical model to determine the drying behavior of infant milk concentrates
A mathematical model was developed to take into consideration the Tg and divergence points. Validation tests on infant formulas were conducted at the INRA drying tower pilot plant. These tests demonstrated that: the powder deposition rate on the chamber wall was inversely correlated with the Tg of the dry concentrates; and the use of drying parameters determined by the method of the divergence point reduces the chamber deposits. A good consistency of the production rate was observed.
Research studies are currently being conducted to refine the predictions and to extend this method to other non-dairy food concentrates (soybean powder ...), and thus generalize this approach.
Laiterie de Montaigu & LISA
ZHU P., PATEL K., LIN S., MÉJEAN S., BLANCHARD E., CHEN XD., SCHUCK P., JEANTET R. Simulating industrial spray drying operations using a reaction engineering approach and a modified desorption method. Drying Technol. 29, 419-428 (2011).
ZHU P., MÉJEAN S., BLANCHARD B., JEANTET R., SCHUCK P. Prediction of dry mass glass transition temperature and the spray drying behaviour of a concentrate using a desorption method. J Food Eng. 105, 460-467 (2011).