Comparative study of particle structure evolution during water sorption: Skim and whole milk powders

Abstract

Surface composition of dairy powders influences significantly a quantity of functional properties such as rehydration, caking, agglomeration. Nevertheless, the kinetic of water uptake by the powders was never directly related to the structure and the composition of the surface. In this work, the effect of relative humidity on the structural reorganization of two types of dairy powder was studied. The water-powder interaction for industrial whole milk powder, and skim milk powder was studied using dynamic vapor sorption. The water sorption isotherms were fitted with a Brunner-Emmet-Teller model and each stage of the sorption curve was analyzed with a Fickian diffusion. The water content in the monolayer predicted for each powder and the moisture diffusivity calculated were discussed and compared. Concurrently, powders microstructure and powders surface under variable relative humidity were assessed by X-ray photoelectron spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray and atomic force microscopy. A correlation between the data obtained from the sorption isotherms and the modifications of structure allowed us to conclude that powder microstructure and chemical state of the components could play an important role in determining the water diffusivity.

Influence of material structure on air-borne ultrasonic application in drying

“…But, since no difference occurred in the growth kinetics, it seems that this has no influence on the development of the surface stickiness attributed to the presence of carbohydrates. Despite a different bulk composition, skim and whole milk powders may have a close surface composition (Murrieta-Pazos et al 2011), and therefore a similar surface "reactivity" regarding agglomeration. This reactivity seems to be linked to the presence of lactose that was found to be the key component in the state diagram of milk regarding glass transition (Vuataz 2002).…”

“…If the surface viscosity becomes locally lower than 10 8 Pa.s, the critical viscosity corresponding to sticky particles, sinter bridges may be formed when particles collide (Palzer 2011). At the same time, fats, known to be overrepresented in the first layers of the particle surface, even in skim milk particles (Kim et al 2009;Murrieta-Pazos et al 2011), may melt and also contribute to adhesion between colliding particles. Despite agglomeration being an important step in the production of "instant milk powder" (Banjac et al 1998(Banjac et al , 2009Koga et al 1989;Neff and Morris 1968), some knowledge gaps still exist especially concerning the mechanisms of agglomerate formation and their relation with initial particle properties and process conditions.…”

Influence of top spray fluidized bed agglomeration conditions on the reconstitution property and structure modification of skim yoghurt powder

“…On the other hand, spray drying step cannot be the only solution in order to obtain powders with good end use properties. Spray dried powders obtained from one stage spray driers have small particle size (<50 µm) that cause poor handling and reconstitution properties due to higher cohesive forces between particles (Chen, Yang, Dave, & Pfeffer, ; Murrieta‐Pazos et al, ). Agglomeration process is defined as the transformation of small native particles into larger size agglomerates.…”

Avaliação Do Índice De Soroproteína Não Desnaturada Como Um Indicador De Tratamento Térmico Para Leite Uht E Leite Em Pó

“…De acordo com Yazdanpanah e Langrish (2013) a partícula de leite em pó com elevados teores de desnaturação proteica tende a apresentar maior tendência à cristalização da lactose durante o período de estocagem, fato este que pode influenciar negativamente o processo de reconstituição do produto ou sua aplicação em outros alimentos. Murrieta-Pazos et al(2011) sugere que a perda das funcionalidades do leite em pó tende a ser mais intensa quando o produto apresenta baixos teores de lipídios, visto a maior concentração de lactose e proteínas desnaturadas na superfície da partícula do pó.…”