The crystallisation of lactose with particular reference to its occurrence in milk powder

Abstract

(the late) C. H. F. FULLER and A. V. BELL X-ray diffraction patterns and infra-red spectra have shown that although the lactose in spray-dried milk powder is normally in the amorphous state, it can sometimes be present as the crystalline a-monohydrate, or in an unusual crystalline form.Studies have been made of the absorption and subsequent loss of moisture in humid atmospheres by (a) spray-and freeze-dried milks, and ( b ) spray-and freeze-dried lactose prepared from lactose solutions. I t is shown that milk powders exposed to these conditions generally contain a-lactose monohydrate, but the spray and freeze-dried lactose produce a mixture of the a-monohydrate and the ,!?-anhydride.For identification purposes all the known crystalline forms of lactose have been prepared and studied by X-ray diffraction and infra-red methods, and it has been found that the above-mentioned unusual crystalline form of lactose found in some milk powders is the anhydrous molecular compound consisting of a-lactose and ,!?-lactose in a molar ratio of 5 : 3. This compound gives an X-ray diffraction pattern which is different from, but an infra-red spectrum similar to, those of the stable &-lactose anhydride.

Lactose Composite Carriers for Respiratory Delivery

“…The composite carrier diffraction patterns had intensities less than that of the regular carrier, most likely due to the significant difference in the primary crystal size (2-10 μm in comparison to 63-90 μm). Interestingly, the composite carriers had an additional peak at 10.6°2θ, suggesting the presence of β-lactose (28) which is produced due to the mutarotation of the α-form during the drying process (29).…”

Kinetics of lactose crystallization and crystal size as monitored by refractometry and laser light scattering: effect of proteins

“…Analyzer software parameters appropriate for crystal analysis were selected for calculation of size distribution: "general purpose", "normal calculation sensitivity" and "irregular particle shape". A refractive index of 1.53 for α-lactose monohydrate crystals, as determined by Bushill et al, was used [3]. A slightly supersaturated lactose solution at 25 °C (27.5 g·100 g -1 water) was prepared as mentioned above and was used as dispersant medium to prevent the dissolution of crystals in the analyzer.…”

“…Additionally, compared with mean diameters such as d 4,3 (the average volume-weighted diameter) or d 3,2 (the average volume-surface diameter), the mode values are scarcely affected by the accidental presence of very small particles, formed by breakage during suspension circulation in the analyzer, and very big particles such as air bubbles. Nevertheless, in the absence of these particles, evolution of d 4,3 and evolution of mode are very similar (Fig. 5).…”

Isothermal batch crystallization of alpha-lactose: A kinetic model combining mutarotation, nucleation and growth steps

“…Analyzer software parameters appropriate for crystal analysis were selected for calculation of size distribution: ''general purpose'', ''normal calculation sensitivity'' and ''irregular particle shape''. A refractive index of 1.53 for alpha-lactose monohydrate crystals, as determined by Bushill et al (1965), was used. A slightly supersaturated lactose solution at 25 C (27.5 g 100 g À1 water) was used as the dispersant medium to prevent the dissolution of crystals in the analyzer.…”