Food Structure


Various methods of preparing emulsions for electron microscopy were examined with peanut oil/protein and ice cream mix emulsions. For transmission electron microscopy {TEM) , fresh peanut oil/bovine serum albumin emulsions were mixed with 2% agar , fixed in phosphate-buffered (pH 7 . 0) 4% glutaraldehyde solution and postfixed in phosphate-buffered (pH ? . 0) 1% osmium tetroxide alternatively , the glutaraldehyde- fixed samples were briefly rinsed in acetone prior to postfixation . Both preparations yielded satisfactory fat globule preservation. Similar emulsions were prepared on loops and suspended over vapors of 25% gJ nt.RrBl r'lehyr'le Rnc'l 1% oRmi urn tetroxide . This preparation resulted in angular fat globules surrounded by a heavy protein precipitate.

Ice cream mix emulsions were prepared for TEM study by mixing with 4% agar , mixing with 2% agarose or using agar tubes. After fixation in phosphate- buffered 4% glutaraldehyde (pH 7 .0) solution , the samples were postfixed in either phosphate/imidazole buffe red (pH 7 . 0) or phosphate- buffered (pH 7 .0) 1% osmium tetroxide . ~lixing with 2% agarose and postfixing in imidazole/phosphate buffered osmium tetroxide yielded the best results . A clearly visible fat membrane and well-delineated fat crystals were observed.

Scanning electron microscope (SEM) studies o!' peanut oil/casein emulsions mixed with 4% agar yielded good results whereas in ice cream mix emul s i ons , the results were inconclusive.

Included in

Food Science Commons