EFFECT OF STRUCTURAL CONSTITUENTS OF CELL-WALL ON THE DIGESTIBILITY OF GRAPE POMACE

In vitro dry matter digestibility, cell wall digestibility, and chemical composition of cell solubles and cell wall fractions were determined from three grape pomace varieties and two standard feeds. Dry matter digestibility of pomace was low (25-38%) compared to standard feeds. Cell solubles content of pomace is comparable to that of standard feeds but is comprised of organic acids (tartaric and acetic) and pectic polysaccharides. Cell wall digestibility of Cabernet Sauvignon pomace is very low (4%), and lignin + cutin level is very high (29%) compared to standard feeds (34-42% and 6-8%, respectively). The observed digestibility is explained in terms of the structural composition of the cell wall fraction. © 1990, American Chemical Society. All rights reserved.