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The crystallisation of lactose with particular reference to its occurrence in milk powder
Author(s) -
Bushill J. H.,
Wright W. B.,
Fuller C. H. F.,
Bell A. V.
Publication year - 1965
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740161010
Subject(s) - lactose , anhydrous , spray drying , powder diffraction , crystallization , chemistry , amorphous solid , crystallography , materials science , food science , chromatography , organic chemistry
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 α‐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. It is shown that milk powders exposed to these conditions generally contain α‐lactose monohydrate, but the spray and freeze‐dried lactose produce a mixture of the α‐monohydrate and the β‐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 α‐lactose and β‐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 α‐lactose anhydride.