Tracheid walls are highly organized polymeric materials consisting of three secondary cell wall layers (S1, S2, and S3), the primary wall layer, and the middle lamella
Pectin, cellulose and hemicellulose are structural polysaccharides in the middle lamella
and primary cell walls of grape cells.
Plant cell wall can be categorized into 3 layers: layer one is adhesive between cell and another called "middle lamella
" composed of calcium pectate (pectic acid binding [Ca.sup.2+]), layer two is a real cell wall synthesized during cell division called "primary cell wall" composed of cellulose, hemicellulose, and pectic substances, and layer three synthesized after primary cell wall or in nongrowing stage of cell called "secondary cell wall" composed of cellulose, hemicellulose, and lignin [27, 28].
in many regions evident of degradation of middle lamella
is recognizable before complete degradation of ray cells bore holes appeared in the adjacent fiber cells The ray cells are penetrated by bore holes which fuse forming elongated cavities further gradually completely degrading the ray leaving behind a wide space.
The fruit softening, during the ripening, is frequently ascribed to enzymatic breakdown of middle lamella
of the cell wall (AWAD, 1993; FISHER et al., 1994).
When produce is immersed in hot calcium chloride solution, calcium helps with cross-linking the pectin chains of the middle lamella
of the cell, creating better cell-cell adhesion and firmer structure.
The lower eyelid consists of two lamellae separated by the orbital septum (some authors consider the septum as the middle lamella
in a trilamellar system) (1,2).
In the surface layers of peracetic-acid-treated boards, all cell wall regions were delignified, with the middle lamella
being the most severely affected.