An imaging method using fluorescence fingerprints (FFs) for visualizing the distribution of gluten and starch in dough without any staining was developed. Wheat flour dough was mixed up to three stages, i.e., under-mixing, optimum-mixing, and over-mixing, and thin sections of the doughs were prepared with a cryotome. Fluorescence images of the sections were acquired in 63 combinations of excitation and emission wavelengths, thereby constructing the FFs of the constituents at each pixel. The cosine similarity between the FFs of each pixel and the FF of pure gluten were calculated and pixels were arranged in order of cosine similarity. Pixels with higher values of cosine similarity were categorized as “gluten” and the rest as “nongluten”. The number of pixels categorized as “gluten” was based on the overall ratio of gluten in the dough. The same process was performed with the FF of pure starch, and all pixels were divided into “starch” and “nonstarch”. Colors were assigned to each division, and the distributions of gluten and starch were visualized. Changes in the distributions of gluten and starch were observed at the over-mixing stage, which suggested the breaking up of gluten and the alteration of gluten and starch.
2013 by Japanese Society for Food Science and Technology