EFFECT OF BAKING ON THE MICROSTRUCTURE OF RYE CELL-WALLS AND PROTEIN

Rye doughs and breads were baked from whole meals milled from two rye varieties, a Canadian Muskate and a Swedish Danko. A study was made of the effect of beta-glucanase and xylanase incubation on the kernel cr oss-sections. Beta-Glucanase studies indicated that beta-glucans are e venly distributed in the endosperm cell walls of the rye kernel. Xylan ase treatment degraded only peripheral endosperm cell walls and had gr eater effect on the Muskate rye kernels. This finding suggests that wa ll structure varies in the different parts of the rye kernel; hence va riety or growing conditions, or both, play an important role in the st ructural features of the plant. Examination of the microstructure of t he doughs and breads indicated that proteins are of major importance i n the structure of the rye dough just after mixing. The Muskate meal w as milled finer, and protein was released from the cells to the dough matrix. The Muskate dough components were tightly stuck together. The Danko dough was less cohesive and more rigid than the Muskate dough ju st after mixing, evidently because of a higher content of big, unbroke n particles in the Danko dough. As baking proceeds, endosperm walls ar e fragmented and, along with starch, their role in the formation of th e continuous matrix increases. The Danko bread contained long, unbroke n aleurone layers that, combined with a weak protein matrix, possibly decreased extensibility of the dough and distorted the gas cell struct ure. The Danko bread crumb was less elastic and more porous than the M uskate bread crumb.