Food Structure


A study was undertaken to establish whether suspension of dry milk powder in isobutanol and 1-octanol during particle size analysis and preparation for scanning electron microscopy introduced artifacts. The median , volume-based diameter, d[v, 0.5], of spray-dried milk powders containing 27-67% lactose changed over time of exposure to isobutanol. No changes in median diameter were observed when powders were exposed to 1-octanol. Changes in particle si ze resulted from solubilization of amorphous lactose and/or recrystallization of lactose on the particle surface. Both a- and ,6 -lactose were formed during contact with isobutanol as indicated by X-ray diffraction and scanning electron microscopy. The magnitude of the characteristic peaks for a- and ,6 -lactose and scanning electron micrographs indicated that the amount of lactose crystal form ed was proportional to the initial amount of amorphous lactose in the sample. 1-Octanol was determined to be a suitable suspension medium for sizing of milk powders containing lactose.

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