Food Structure


S. H. Yiu


Fluorescence techniques were used to study the microstructure of several varieties of cheese. The size and distribution of fat globules in various cheeses were demonstrated by fluorescent staining using Nile Blue A as a marker. Acridine Orange was used as a dye to detect structural differences between casein matrices of various cheese varieties. Differences between the ripe and the less- ripe zones of Ca membert cheese were detected by staining the cheese sections with Acridine Orange and Nile Blue A separately, and then comparing the re sults of the stainings. The Nile Blue A stain ing s howed that fat globules were absent from the ripe zone immediately below the surface molds, but were present in other areas of the cheese . Results from the Acridine Orange staining indicated that the protein matrix in the same area was different. both struc turally and chemi cally, from the protein ma trix in other locations . The findings indicated the presence of degraded proteins and fats in the ripe zo ne of the Camembert cheese. In another experiment . the presence of small crystalline inclusions, 10- 30 ~ m in diameter, and their distribution in cheese were detected by various staining methods including the Von Kossa technique. Acridine Orange was also shown by the present study to be useful as a detecting reagent for revealing the crysta lline structures. Two fluorochromes. Acridine Orange and Acriflavine , were used separately to reveal the presence and distribution of the microflora that was us ed in the ripening and flavor development of several cheese varieties.

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