A metal-impregnation technique (tannin-ferrocyanide- osmium tetroxide) and thin metal coating imparted excellent preservation , and electric and thermal properties to milk products for scanning electron microscopy, resulting in high- resolution images. Three nanometer resolution was obtained, with minimal edge effects, charging , thermal drift, and decoration. Samples were fixed in 2% gluta raldehyde, cryoprotected in 70% ethanol, and cryofractured, exposing internal structure. Fat was extracted with Freon 113 and the sample were metal -impregnated with 1.0% osmium tetroxide and 1.5% potassium ferrocyanide, reduced with 1% hydroquinone, dried using !he critical-point drying melhod , and ion beam sputter-coated with 2-5 nm of iridium. Hard cheeses, cream cheese, and yogurt were prepared and imaged using this procedure . Images were recorded at low and high magnifications.
McManus, William R.; McMahon, Donald J.; and Oberg, Craig J.
"High-Resolution Scanning Electron Microscopy of Milk Products: A New Sample Preparation Procedure,"
4, Article 8.
Available at: http://digitalcommons.usu.edu/foodmicrostructure/vol12/iss4/8