PRACTICAL ASPECTS OF ELECTRON-MICROSCOPY IN DAIRY RESEARCH

Milk products are based mostly on casein micelles, fat globules, and w hey proteins. The former two constituents are corpuscular and whey pro teins become corpuscular when coagulated. Structural changes in these basic constituents during processing have been studied by electron mic roscopy. This review discusses the structures of yoghurt, curd, cheese s (hard cheeses, mould-ripened cheeses, cream cheeses, and process che ese), cream, milk powders, and nontraditional dairy products. Defects and deviations from traditional structures of these products are expla ined where the causes are known. Examples of such causes are foaming o f milk, presence of unusual ingredients (bacterial polysaccharides, wh ey protein concentrates), and alterations in manufacturing procedures (temperature regimens, ultrafiltration, or microparticulation). The re view emphasizes the importance of electron microscopy alone and also i n conjunction with X-ray microanalysis and image analysis. Data obtain ed by structural studies facilitate understanding of sensory propertie s of the products and help to develop new foods with desired propertie s. The review is illustrated with 29 micrographs and supported by 165 references.