Life Sciences Commons^™

Complementary Replicas Of Ultra-Rapidly Frozen Specimens, M. J. Costello, R. D. Fetter, T. G. Frey

Scanning Electron Microscopy

Complementary freeze-fracture replicas have been prepared of ultra-rapidly cooled specimens in the absence of chemical pretreatments. The grid-sized replicas were stabilized by open mesh gold grids during the cleaning process and, after cleaning, were supported on thin Formvar films. The complementary replicas were valuable for describing artifacts, for interpreting the nature of fracture planes and for evaluating the resolution of replicas. Complementary images demonstrated that heat emitted from resistance electrodes or electron guns during evaporation can seriously distort fracture surfaces even for samples held at -150°C. Complementary images of crystalline membranous cytochrome c oxidase helped establish that fracturing reveals hydrophilic …

Characterisation Of Milk Proteins In Confectionery Products, J. F. Heathcock

Food Structure

The proteins from milk play an important part in the structural properties of confectionery products. These properties will in turn influence texture and flavour. Electron microscopy techniques have been used to examine milk chocolate, caramel and fudge and to locate and characterise the milk proteins within their structures. Following scanning electron microscopy examination of the products at low temperature, thin sectioning and freeze-fracture were used to resolve the fine ultrastructure of casein and whey proteins.

A chocolate prepared from milk crumb could be distinguished from one made with a dry milk powder on the basis of a more even distribution …

Combining Microscopy And Physical Techniques In The Study Of Cocoa Butter Polymorphs And Vegetable Fat Blends, J. D. Hicklin, G. G. Jewell, J. F. Heathcock

Food Structure

Transmission electron microscopy, differential scanning calorimetry and X-ray diffraction have been used to study the cocoa butter polymorphs and blends of cocoa butter with a hydrogenated vegetable fat. The results indicate the presence of six polymorphs and confirm observations made by other workers. Vegetable fat addition affects both the molecular structure and the morphology of the crystals observed. After temperature cycling, a blend containing 50% vegetable fat developed two crystal types and differences in the X-ray pattern were apparent. Correlations could be made between the known molecular structure and the morphology observed in most of the polymorphs. In selected cases, …