Cereals & Grains Association
Log In

Visualization of gluten, starch, and butter in pie pastry by fluorescence fingerprint imaging
M. KOKAWA (1), J. Sugiyama (2), M. Tsuta (2), K. Fujita (2), M. Yoshimura (2), M. Shibata (2), T. Araki (1), H. Nabetani (2). (1) The University of Tokyo, Tokyo, Japan; (2) National Food Research Institute, National Agriculture and Food Research Organization, Tsukuba, Japan

Gluten, starch and fat make up the structure of pastry doughs, and the texture of the product is strongly influenced by the way these constituents are distributed in the dough. For example, puff pastry and flaky pastry differ in the way fat is distributed in the gluten-starch matrix, and this changes the flakiness and crispness of the finished product. The objective of this study was to visualize gluten, starch and butter in puff pastry dough without any staining by use of a fluorescence fingerprint (FF). The FF, also known as a excitation-emission matrix (EEM), is a set of intrinsic fluorescence spectra acquired at multiple excitation wavelengths. Because the pattern of the FF is unique for each substance, constituents in a sample can be predicted by analyzing the FF pattern. The distribution of constituents can be predicted by using a digital camera to acquire fluorescence images of a sample at all combinations of excitation and emission wavelengths that construct the FF, thereby acquiring a set of data consisting of the FF of each pixel. Samples of 10μm thickness were made from puff pastry dough, gluten, starch, and butter, and fluorescence images of the samples were acquired. The FF of each pixel in the dough image was analyzed with non-negative matrix factorization (NNMF) and the amount of gluten, starch, and butter existing at that point was obtained. By showing the amounts of gluten, starch, and butter at each point in gradations of red, green, and blue, respectively, the distribution image of these three constituents was obtained. Finally, the imaging method was validated by double-staining the same dough sample with fluorescent dyes for protein and fat, and comparing the stained image with FF imaging method. The FF imaging method succeeded in visualizing the gluten strands and starch granules with high accuracy.

View Presentation