Confocal Microscopy of Bread

Abstract

The microscope, in its various forms, is a most appropriate technique for evaluating food structure. Various researchers have helped elucidate the location and distribution of cereal components which in turn related to their functionality in baked goods such as bread (1,2,3,4). Laser Scanning Confocal Microscopy (LSCM) is unlike other light microscopy techniques (e.g. fluoresence, bright field and polarized light) in which non-coherent light is applied and all the reflective light is collected, including that above and below the focal plane, resulting in a blurred or diffused image for a specimen with considerable thickness (5). The confocal microscope uses a point light source (laser) which is focused on a small volume within the specimen rendering an image of in-focus plane only, with the out-of-focus parts appearing as black background (4). Additionally, the confocal microscope provides an opportunity to observe a 3-D image without the need to physically section the sample, allowing a disturbance-free observation of the specimen. Although Transmission Electron Microscopy (TEM) can provide a 3-Dimensional view of the specimen, the sample must be dried or frozen (or replicated with platinum and carbon) since TEM is carried out in vacuum. Confocal microscopy can be used to observe dynamic process such as dough formation (5) since no such restriction on sample preparation is necessary. Finally, two powerful techniques such LSCM and fluoresence microscopy can be combined to localize and identify different components by using specific fluorescent labels (such as fluorescein for protein, Texas Red for starch, and Nile Blue for lipids).