Influence of the drying step in the steam-jet granulation process of dairy powders
2018
Person, Mathieu | Cuq, Bernard | Duri-Bechemilh, Agnès | Le Floch-Fouéré, Cécile | Schuck, Pierre | Jeantet, Romain | Science et Technologie du Lait et de l'Oeuf (STLO) ; Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST | Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)
Steam-jet granulation process consists in agglomeration mechanisms promoted by the wetting of fine particlesand colliding them to generates the agglomerates, and in consolidation mechanisms of the agglomerates bydrying stage. The aim of the present study was to evaluate the influence of the drying step on the properties ofthe agglomerates. Experiments were conducted using an original pilot system with different drying conditions(time and temperature). We demonstrated that the mechanisms induced by drying stage contribute to the finalstructure and characteristics of the agglomerates. On the other hand, the changes in drying temperature (70, 90,or 110 °C) did not significantly impact the structural properties. The rehydration properties of the agglomerateswere found to depend on the changes in water content. During the first minutes of drying, a rapid decrease of thewetting time of the agglomerates was observed and associated with rapid lactose crystallization. For long dryingtimes, the large decrease in water content induced a considerable increase in the glass transition temperature,leading to a delay in the plasticization effect of the water during rehydration. The drying stage is a key factor tocontrol the stability and functional properties of agglomerates.
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