Applications of Confocal Microscopy to Fat Globule Structure in Cheese

Direct In Situ Viability Assessment of Bacteria in Probiotic Dairy Products Using Viability Staining in Conjunction with Confocal Scanning Laser Microscopy

“…Some background fluorescence of the protein matrix was seen in the green channel, although this was at a lower intensity than bacterial fluorescence. Fat globules appeared as dark rounded regions by negative contrast as observed in a previous study (8). The homogeneous staining of the protein matrix with SYTO9 was most likely due to nonspecific binding of the stain to milk proteins.…”

Cheese structure and current methods of analysis

“…Studies using CLSM have examined the fat globule structure in cheese (Gunasekaran & Ding, 1999;Muthukumarappan, Gunasekaran, Johnson, & Olson, 1995), milk gelation and cheese melting (Auty, Fenelon, Guinee, Mullins, & Mulvihill, 1999), permeability of rennet casein gels (Zhong, Daubert, & Velev, 2004), the effect of the pasta filata process on fat globule coalescence in Mozzarella cheese (Rowney, Roupas, Hickey, & Everett, 2003b) and Cheddar cheese (Everett & Olson, 2003;Everett, Ding, Olson, & Gunasekaran, 1995), localisation of probiotic bacterial cells (Auty et al, 2001a) and starter cells in cheese (Hannon, Lopez, Madec, & Lortal, 2006), location of exopolysaccharides (EPS) in cheese (Hassan, Frank, & Qvist, 2002), and correlation with sensory data of acid milk gels (Pereira, MatiaMerino, Jones, & Singh, 2006). Non-confocal fluorescence microscopy with dual-labelling of the fat and casein components has shown the importance of casein hydrolysis and fat in ripening Camembert cheese (Yiu, 1985).…”

“…Analysis of the size and shape of fat areas in cheese can be done by computerised 2D and 3D analysis of confocal micrographs with appropriate fluorescent staining of the fat or the aqueous protein phase (Everett et al, 1995). Aggregates of fat globules in Cheddar cheese are seen to align along the direction of the casein fibres (Hall & Creamer, 1972), presumably due to the forces imposed by the cheddaring process.…”

Comparison of microscopy techniques for the examination of the microstructure of starch-containing imitation cheeses

“…Other imaging techniques such as confocal microscopy (Auty, Fenelon, Guinee, Mullins, & Mulvihill, 1999;Everett, Ding, Olson, & Gunasekaran, 1995) and TEM (Drake, Chen, Gerard, & Gurkin, 1998;Tunick, Van Hekken, Cooke, & Malin, 2002) have also been used to examine cheese microstructure. However these techniques have some limitations.…”