Fluidisation of whey powders above the glass-transition temperature

Moisture sorption and stickiness behaviour of hydrolysed whey protein/lactose powders

“…These authors also concluded that delays to crystallisation are dependent on the interaction behaviour between lactose and protein. Ibach and Kind (2007) and Nijdam et al (2008) also reported that proteins and salts increase the mean path length required for migration and association of lactose molecules. Given the similarity in mineral contents of WPH11 and WPH32, it appears that the role of salts was not responsible for differences in delays to crystallisation between these two powders.…”

Influence of milk proteins on the development of lactose-induced stickiness in dairy powders

“…Haque and Roos (2004) showed that T cr ÀT g (where T cr is the crystallisation temperature) increases in the presence of proteins and suggested that crystallisation was affected by lactose-protein interactions at a molecular level and that such interactions may also affect the rates of other changes above and below an observed T g . Ibach and Kind (2007) and Nijdam, Ibach, and Kind (2008), proposed that crystallisation of amorphous lactose, in partially crystalline whey powders, is delayed due to the concentration of proteins and salts in the non-crystalline powder matrix. Ibach and Kind (2007) suggested that the presence of proteins and salts effectively dilutes the concentration of amorphous lactose and lengthens the mean path length required for lactose molecules to migrate to bond with other lactose molecules.…”

Fast crystallization of lactose and milk powder in fluidized bed dryer/crystallizer

“…Fig. 2 The upper limit of fluidization on the relative humidity of process air, under lactose-base which materials can be fluidized Nijdam et al (2008) showed that the difference between the upper limits of fluidization for partially crystallized whey powder and fully crystallized whey powder was that fully crystallized whey powder can be fluidized up to a relative humidity of approximately two times greater than that of partially crystallized whey powder at any given air temperature. In this study, the same behaviour has been found for crystallized skim milk powder and amorphous fresh spray-dried skim milk powder, in the sense that fully crystallized skim milk powder can be fluidized up to a relative humidity that is approximately two times higher than fresh spray-dried skim milk powder at any corresponding air temperature.…”

“…High heat and mass-transfer rates, high yields and lower residence times are advantages that have made this technique into a robust and efficient industrial technique. Some researchers have recommended that the amorphous lactose fraction could be treated in a crystallization facility after spray drying to crystallize lactose-containing powders and thus limit the caking tendency of the powder (Hynd 1980;Nijdam et al 2008;Roetman 1979). No attempt was reported (Hynd 1980;Nijdam et al 2008) to decrease the degree of amorphicity or assess the progressive change in crystallinity of lactose or milk powder during processing at different temperatures and humidities in fluidized beds.…”

“…Palzer (2005) shows that the whole powder bed will collapse immediately when reaching the calculated critical moisture level when using air having a relative humidity of 90%. In addition, Nijdam et al (2008) found that a bed of amorphous whey powder could not be re-fluidized by a further increase in air velocity after a slight increase in air humidity above the fluidization limit. This humidity limit represents a point above which no amount of additional mechanical energy, either in the form of air flow or mechanical force (by vibration or stirring), can fluidize the milk powder in the fluidized bed.…”