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La Boissière-de-Montaigu, France

Zhu P.,French National Institute for Agricultural Research | Zhu P.,Agrocampus Ouest | Mejean S.,French National Institute for Agricultural Research | Mejean S.,Agrocampus Ouest | And 5 more authors.
Journal of Food Engineering | Year: 2011

A predictive tool (SD 2P®) based on a drying by desorption method was recently developed in order to determine the key process parameters values prior to spray drying. However, the SD 2P® software cannot currently take into account the risk of stickiness during the process. In the study reported here, new standardized desorption method was tested and with this new method an equation was proposed to evaluate the dry glass transition temperature (T g) of a concentrate according to its total solid content, its viscosity and its average evaporation rate. The concentrate's behaviour during spray drying could then be predicted on the basis of the T g. Four validation experiments were performed using different infant formula samples; the concentrates prepared from the four infant formula powders were then spray dried using a one-stage pilot dryer. The drying parameters were predicted using the SD 2P® software. The results showed that the T g predicted using this method were 18-30 °C higher than T g measured by DSC (Differential Scanning Calorimetry). The drying temperatures predicted by SD 2P® corresponded well to the values measured and this new method can correctly predict the behaviour of a concentrate with regard to spray drying. The advantage of the method presented here is that it can easily and quickly evaluate a concentrate's T g range and spray drying behaviour by direct analysis of the fresh concentrate sample. © 2011 Elsevier Ltd. All rights reserved. Source


Zhu P.,French National Institute for Agricultural Research | Patel K.,Monash University | Lin S.,Monash University | Mejean S.,French National Institute for Agricultural Research | And 4 more authors.
Drying Technology | Year: 2011

A predictive tool using a thermodynamic approach has recently been developed to determine several important gas-feed parameters for industrial spray-drying processes. In this approach, a desorption behavior of materials was evaluated and the behavior was linked with overall heat and mass balances over the dryer. Using the desorption behavior of materials and the overall heat and mass balances, a spray-drying software SD2P® was designed at the Institut National de la Recherche Agronomique (INRA) in France. The SD2P® software allows the prediction of optimal inlet drying air temperatures with acceptable accuracy (95-99% accuracy) for spray drying of dairy products. In order to predict detailed quality parameters and stickiness behavior of a product during processing, the reaction engineering approach (REA) was combined with a modified desorption method. A traditional experimental setup is replaced with a new setup, which is described in this article. Drying kinetics parameters were predicted using this new setup. Important gas-feed parameters were predicted using the 1D simulation-based software and compared with SD2P® predictions and are reported here. © 2011 Taylor & Francis Group, LLC. Source


Zhu P.,Laiterie de Montaigu | Mejean S.,French National Institute for Agricultural Research | Mejean S.,Agrocampus Ouest | Blanchard E.,Laiterie de Montaigu | And 4 more authors.
Dairy Science and Technology | Year: 2013

A desorption method based on a thermodynamic approach has recently been developed to evaluate the behaviour of dairy concentrates during drying. Involving overall heat and mass balance throughout the dryer, this approach can determine several key gas-feed parameters for industrial spray-drying processes. Spray-drying software (SD2P®) was then designed following this approach to predict the optimal inlet drying air temperatures with acceptable accuracy (95-99% accuracy) for spray-drying of dairy products. However, the mass change of the sample was indirectly determined from the change in the relative humidity of the air during desorption, which could be a source of error below the detection threshold of the thermo-hygrometric sensor. In order to measure directly the mass change during drying by desorption, a modified drying-by-desorption method was investigated in this study. The novel method used a precise microbalance and a modified desorption cell which permitted measurement of the mass change of the sample and the relative humidity of the air at the same time. Different materials (water, skim milk, infant formulae, etc.) were tested using this new method. The results obtained with direct (microbalance) and indirect (thermo-hygrometer) measurements were found to be highly consistent (coefficient of determination 1). This confirmed that the mass change estimation by the original desorption method was correct overall under current conditions. Moreover, the proposed new desorption method makes it possible to monitor water transfer with constant accuracy over the entire desorption process, thus permitting reliable study of the mass transfer phenomena throughout experiments. © 2012 INRA and Springer-Verlag France. Source

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