title: Powder wettability at a static air-water interface.
abstract: The reconstitution of a beverage from a dehydrated powder involves several physical mechanisms that determine the practical difficulty to obtain a homogeneous drink in a convenient way and within an acceptable time for the preparation of a beverage. When pouring powder onto static water, the first hurdle to overcome is the air-water interface. We propose a model to predict the percentage of powder crossing the interface in 45 s, namely the duration relevant for this application. We highlight theoretically the determinant role of the contact angle and of the particle size distribution. We validate experimentally the model for single spheres and use it to predict the wettability performance of commercial food powders for different contact angles and particles sizes. A good agreement is obtained when comparing the predictions and the wettability of the tested powders.
authors.affiliation: Nestlé PTC Orbe, 3 Rte de Chavornay, CH-1350 Orbe, Switzerland. Electronic address: julien.dupas@rdor.nestle.com.
authors.forename: Julien
authors.initials: J
authors.lastname: Dupas
authors.affiliation: Nestlé Research Center, Rte du Jorat 57, CH-1000 Lausanne 26, Switzerland.
authors.forename: Laurent
authors.initials: L
authors.lastname: Forny
authors.affiliation: Nestlé Research Center, Rte du Jorat 57, CH-1000 Lausanne 26, Switzerland; Department of Chemical and Process Engineering, University of Surrey, Guildford, UK.
authors.forename: Marco
authors.initials: M
authors.lastname: Ramaioli
keywords: Contact angle; Dissolution; Floating; Powders; Sinking; Wetting