Microstructure of Sasakamaboko: Stainability of Surimi Protein and Amounts of Mixed Starch and Mingled Air Bubbles.

The stainability of surimi protein in sasakamaboko products and uncooked surimi was examined. The components originating from fish, the amount of mixed starch, and the mingled air bubbles during processing were also studied.<BR>Four brands of sasakamaboko products, each of which were broiled, and their uncooked surimi samples were used in this study. Two samples were taken from both sasakamaboko and uncooked surimi. One was fixed in 10% formalin and another was frozen in a mixture of dry ice and acetone. Paraffin sections or frozen sections were stained with Azan, Hematoxylin-Eosin (H-E), Picrosirius (PS) and acrolein-Schiff (AS) to assess protein stainability. Starch was stained with periodic acid-Schiff (PAS) and iodine. The proportions of starch granules and air bubbles were obtained by measuring their cross-sectional areas present in a fixed area.<BR>With the sasakamaboko products, the superficial thin (ST) layer was stained more intensely with Eosin and AS than the interior. In Azan stain, the ST layer was stained with Azocarmine G, whereas the interior was stained with Aniline Blue. In PS stain, the ST layer was stained with picric acid, whereas the interior was stained weakly with Sirius Red. The uncooked surimi was stained uniformly with Eosin, AS, Azocarmine G in Azan stain, and picric acid in PS stain. The findings show that broiling changes stainability of surimi protein. Collagen fibers stained with Aniline Blue and Sirius Red were dispersed in the sasakamaboko products and uncooked surimi. Gelatinized and swollen or multiform starch granules were dispersed in the products. Round or multiform starch granules were dispersed in the surimi. The round starch granules in the surimi and a few round starch granules dispersed at the center of two brands of the sasakamaboko products showed birefringence. Starch was diffused from some starch granules into surimi protein in the sasakamaboko products and uncooked surimi. The sasakamaboko products contained 1.8∼5.8% starch granules and 12.7∼18.2% air bubbles. Some brand included a very small amount of finely ground scales.