Food Microstructure and Starch Digestion - Advances in Food and Nutrition Research - page 171

et al., 2008 ) . The reduction in cohesiveness between starch and proteins of
dough may increase the starch accessibility to

-amylase that leads to greater
digestibility. A detailed review has been published recently on the impor-
tance of structure development at microscopic and molecular level during
pasta making and its relationship with starch and protein digestibility
( Petitot, Abecassis, &Micard, 2009 ) . The authors emphasized that the com-
pact structure of pasta, the encapsulation of starch by proteins, and the phys-
ical structure of starch are mainly responsible for the reduced enzymic
susceptibility of starch in cooked pasta.
Assimilation of starches may be enhanced by a series of processes, such as
cracking of the grain, and then converting it from a crystalline to a gel struc-
ture, which promotes efficient entry into the luminal polar solution for
interaction with the

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-amylases ( Goni, Garcia-Alonso, & Saura-Calixto,
1997 ). Effects of microwave heating and other heating methods, such as
cooking and pressure cooking, on the rate of hydrolysis and GI were com-
pared between kudzu starch and maize starch ( Geng, Zongdao, & Toledo,
2003 ). The rate of hydrolysis for both the starches increased following heat
treatment and to a greater extent with microwaving cooking, which may be
attributed to the greater penetration of heat during microwave heating. The
change in degree of susceptibility of the starches toward enzymatic digestion
is a function of the extent to which the microwave heating process induced
any changes in the crystalline structure of the starches ( Anderson & Guraya,
2006 ). Recently, the effects of microwave treatment time on the digestibility
of Canna edulis starch have been reported by Zhang, Wang, and Shi (2009) .
Their results indicated that both low (400 w) and high (1000 w) microwave
powers are advantageous to the formation of RS. Irradiation has been used
to extend the shelf life and safety of food and is permitted now in many
countries. Degradation of starch polymers by gamma irradiation may result
in reduction in molecular weight of amylose and amylopectin, decreased vis-
cosity, and increased acidity ( Abu, Duodu, & Minnaar, 2006; Bao, Ao, &
Jane, 2005 ). Chung and Liu (2009) studied the effect of gamma irradiation
on the enzymatic digestibility of corn starch and reported that a slower dose
rate decreases the RDS and SDS contents and increased RS content.
During the gelatinization of starch, the crystalline structure of amylopec-
tin disintegrates and the polysaccharide chains take up a random configura-
tion, thus causing the swelling and rupturing of the starch granules ( Singh,
Kaur, & McCarthy, 2007 ). After gelatinization and cooling of the cooked
starch, recrystallization of the starch chains starting to occur. Amylose aggre-
gation and crystallization in the cooked starch pastes have been reported to

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