Biology Reference
In-Depth Information
Sodhi, 2002
)
. During cooking, changes in the foodmicrostructure and texture
occur due to continuous heat treatment over a certain period. These changes
have beenmainly associatedwith the gelatinization behavior of starch (
Alvarez,
Kaur, et al., 2008; Singh et al., 2002
)
though cell wall andmiddle lamellae struc-
tural components alsoplay a part (
Alvarez&Canet, 1998;Ormerodet al., 2002;
Starch in some natural foods such as legumes is situated inside the living
cotyledon cells (
Hahn, Jones, Akhavan, & Rockland, 1977
)
. Primary cell
walls of growing and fleshy tissues have a conserved general composition
of cellulose, hemicelluloses, and pectin
(
Chanda, 2005
). The noncellulosic
material acts as a “glue” that holds the microfibrils of cellulose together
which in turn is responsible for the stability of cell walls (
Carpita &
Gibeaut, 1993
). The starch granules in beans are present in the cotyledon
cells and are embedded in the protein matrix of the cellular contents
(
Daussant, Mosse, & Vaughan, 1983
)
. This situation restricts the complete
swelling of starch during gelatinization due to steric hindrance and other
limiting effects including restricted water availability.
Hahn et al. (1977)
and
Kon, Wagner, Becker, Booth, and Robbins (1971)
observed birefrin-
gence of intracellular starch granules when microscopically examining
cooked beans using plain polarized light.
Wursch, Delvedovo, and
Koellreutter (1986)
pointed out that the thick and mechanically resistant
nature of the cotyledon cell walls in legumes prevent complete swelling
of starch granules during gelatinization, which may restrict their interaction
with digestive enzymes.
Depending on the botanical origin, physicochemical characteristics,
and type of processing, starch-based carbohydrates are hydrolyzed at differ-
et al., 2010
)
. Cooking or thermal treatment during processing of starch leads
to an increase in the rate of hydrolysis by gelatinizing the starch and making it
more easily available for enzymatic attack during digestion.
Two case studies (Case I: cooked potatoes and Case II: beans) have
been discussed to understand the microstructure of natural foods and its role
during starch digestion.
