In the present paper redispersion and wettability experiments of spray-dried whey protein stabilized emulsions are presented. Emulsion droplet size after redispersion gives information about eventual coalescence between emulsion droplets in the powder matrix during drying or storage, resulting in an increase in emulsion droplet size after redispersion. Results from redispersion experiments are combined with previously presented knowledge about powder surface composition and particle structure to elucidate internal processes in the powder matrix and external processes on the powder surface during drying and storage of whey protein powder. The results show that with addition of lactose to whey protein stabilized emulsions, emulsion droplet structure remains intact in the powder matrix during drying since the emulsion droplet size in the redispersed spray dried emulsion is unchanged. In the absence of lactose there is a growth in emulsion droplet size after redispersion of the spray-dried whey protein stabilized emulsion showing that a coalescense of emulsion droplets occurs during the drying or redispersion process. Storage of the whey protein stabilized powders in humid atmosphere (relative humidity 75 %, 4 days) induces changes in some powders. When the powder contains a critical amount of lactose there is a remarkable increase in emulsion droplet size after redispersion of humid stored powders as compared to the emulsion before drying and compared to the redispersed dry-stored powder. In addition, there is a release of encapsulated fat after humid storage of lactose containing powders detected by ESCA. For powders which do not contain any lactose there is no increase in emulsion droplet size after storage in humid atmosphere as compared to the redispersed dry stored emulsion. Addition of only a small amount lactose prevents coalescence of emulsion droplets and the subsequent increase in droplet size during drying. If the lactose content is kept rather low there is neither an effect on the droplet size after storage under humid conditions nor a release of fat onto powder surfaces detected. Furthermore, wettability of the spray-dried whey-protein stabilized emulsions by water is presented. It is concluded that it is beneficial to wettability in water to have as high coverage of lactose on the powder surface as possible. In addition, a review of particle structure for powders with various composition is presented.