Food Structure


Fluorescence microscopy was used to study the microstructure of oat cell walls during concentration of oat bran and isolation of ,B-glucans. The bran concentrate separated from c.v. Nasta contained mainly the aleurone and subaleurone endosperm layers, whereas that separated from a commercial bran mixture contained more endosperm . In contrast to Nasta, the commercial bran mixture contained ,B-glucan degrading enzymes, which survived the ,B-glucan isolation procedure. In the presence of enzymes, the solubility and yield of ,B-glucans improved but the viscosity decreased when it was measured at the same ,B-glucan concentration. For inactivation of the enzymes, 80% ethanol at 78 C was more effective than 80% or 94% ethanol at 60 •C or 94 % ethanol at 78 •c. The yield of 11-glucan extracted was higher from Nasta bran concentrate than from commercial bran concentrate, and after alkaline ex traction the Nasta solid residue exhibited intense red fluorescence in the aleurone and subaleurone endosperm cell walls. The solid residue from commercial bran had areas of starchy endosperm cell walls provided the B-glucan degrading enzymes were inactivated.

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