title: Water droplet spreading and recoiling upon contact with thick-compact maltodextrin agglomerates.
abstract: BACKGROUND
  The food and pharmaceutical industries handle a number of compounds in the form of agglomerates which must be put into contact with water for rehydration purposes. In this work, liquid-solid interaction between water and maltodextrin thick-compact agglomerates was studied at different constituent particle sizes for two compression forces (75 and 225 MPa).
  
  
  RESULTS
  Rapid droplet spreading was observed which was similar in radius to the expected one for ideal, flat surfaces. Contact angle determinations reported oscillations of this parameter throughout the experiments, being indicative of droplet recoiling on top of the agglomerate. Recoiling was more frequent in samples obtained at 225 MPa for agglomerate formation. Agglomerates obtained at 75 MPa exhibited more penetration of the water. Competition between dissolution of maltodextrin and penetration of the water was, probably, the main mechanism involved in droplet recoiling. Micrographs of the wetting marks were characterized by means of image analysis and the measurements suggested more symmetry of the wetting mark at higher compression force.
  
  
  CONCLUSIONS
  Differences found in the evaluated parameters for agglomerates were mainly due to compaction force used. No significant effect of particle size in recoiling, penetration of water into the agglomerate, surface texture and symmetry was observed.
authors.affiliation: Departamento de Graduados e Investigación en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala s/n. Col. Santo Tomás, México.
authors.forename: Lesvia Sofía
authors.initials: LS
authors.lastname: Meraz-Torres
authors.forename: María Ximena
authors.initials: MX
authors.lastname: Quintanilla-Carvajal
authors.forename: Darío I
authors.initials: DI
authors.lastname: Téllez-Medina
authors.forename: Humberto
authors.initials: H
authors.lastname: Hernández-Sánchez
authors.forename: Liliana
authors.initials: L
authors.lastname: Alamilla-Beltrán
authors.forename: Gustavo F
authors.initials: GF
authors.lastname: Gutiérrez-López
mesh_terms: D000465:Algorithms; D003890:Desiccation; D005503:Food Additives / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007091:Image Processing, Computer-Assisted; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D010316:Particle Size; D010539:Permeability; D011134:Polysaccharides / Q000737:chemistry* / Q000648:ultrastructure; D016062:Porosity; D012995:Solubility; D013499:Surface Properties; D013500:Surface Tension; D014783:Viscosity; D014867:Water / Q000032:analysis*; D017155:Wettability
chemical_list: D005503:Food Additives; D011134:Polysaccharides; D014867:Water; C008315:maltodextrin