22
hydrolysis as compared to cereals which have A-type crystallinity (Mir et al. 2013).
Leguminous starch contains higher levels of amylose as compared to cereal and
pseudocereal starches which reflects their high RS content (Mikulíkova et al. 2008).
Quick retrogradation of cooked leguminous starch makes it exceptionally resistant
to hydrolysis (Tharanathan and Mahadevamma 2003).
RS content varies from a few percent to 80% in the legumes. It may further
increase or decrease due to hydrothermal processing, depending on the variety of
legumes and parameters of processing (Giczewska and Borowska 2003).
Processing had a great impact on the RS and SDS content of foods, and generally
RS contents are reduced by severe and longer periods of processing. RS content of
cooked rice reduced from 12% to 5% during grinding where as RS content of oats
reduced from 16% to 3% during cooking (Muir and O’Dea 1992). Autoclaving,
baking, flaking, and parboiling are known to influence starch digestibility and the
yield of SDS (Brand et al. 1985; Holm et al. 1985; Casiraghi et al. 1993; Kingman
and Englyst 1994). During pullulanase debranching and cooling treatment of the
cooked waxy maize starch, short-term retrogradation occurs as a result of the crystallization of the amylose fraction, leading to maximum SDS formation (Miao
et al. 2009).
Formation of Resistant Starch and Slowly Digestible Starch
Different modifications of starch like physical, chemical, enzymatic treatments,
irradiation and genetic modifications have been employed for the formation of RS
and SDS. Some of these modifications are described as follows:
Physical Modifications
Physical treatments for preparation of SDS and RS include hydrothermal treatments, recrystallization, polymer-entrapment, and extrusion. When starch is heated
to various levels, it leads to the formation of RS and SDS. RS was obtained by cooking the starch above its gelatinization temperature and drying simultaneously on
heated rolls like drum driers and extruders (Holm et al. 1988). Gelatinization of
starch at 120 °C for 20 min, followed by cooling to room temperature also provides
good yields of RS (Garcia-Alonso et al. 1999). High yields of SDS (39.3–56.7%)
were obtained by dual retrogradation treatment (gelatinization-retrogradationgelatinization- retrogradation) in rice starch (Tian et al. 2013). Good yields of RS3
were also obtained by various combinations of time and temperature treatments to
various sources of native starch. The temperature treatments were autoclaving the
starch at 110 °C (Berry 1986), at 121 °C (Sievert and Wursch 1993), at 127 °C
(Berry 1986), at 134 °C (Berry 1986), or at 148 °C Sievert and Pomeranz 1989) for
periods ranging from 30 min to 1 h. Recently effects of autoclaving temperature
B. A. Ashwar et al.
hydrolysis as compared to cereals which have A-type crystallinity (Mir et al. 2013).
Leguminous starch contains higher levels of amylose as compared to cereal and
pseudocereal starches which reflects their high RS content (Mikulíkova et al. 2008).
Quick retrogradation of cooked leguminous starch makes it exceptionally resistant
to hydrolysis (Tharanathan and Mahadevamma 2003).
RS content varies from a few percent to 80% in the legumes. It may further
increase or decrease due to hydrothermal processing, depending on the variety of
legumes and parameters of processing (Giczewska and Borowska 2003).
Processing had a great impact on the RS and SDS content of foods, and generally
RS contents are reduced by severe and longer periods of processing. RS content of
cooked rice reduced from 12% to 5% during grinding where as RS content of oats
reduced from 16% to 3% during cooking (Muir and O’Dea 1992). Autoclaving,
baking, flaking, and parboiling are known to influence starch digestibility and the
yield of SDS (Brand et al. 1985; Holm et al. 1985; Casiraghi et al. 1993; Kingman
and Englyst 1994). During pullulanase debranching and cooling treatment of the
cooked waxy maize starch, short-term retrogradation occurs as a result of the crystallization of the amylose fraction, leading to maximum SDS formation (Miao
et al. 2009).
Formation of Resistant Starch and Slowly Digestible Starch
Different modifications of starch like physical, chemical, enzymatic treatments,
irradiation and genetic modifications have been employed for the formation of RS
and SDS. Some of these modifications are described as follows:
Physical Modifications
Physical treatments for preparation of SDS and RS include hydrothermal treatments, recrystallization, polymer-entrapment, and extrusion. When starch is heated
to various levels, it leads to the formation of RS and SDS. RS was obtained by cooking the starch above its gelatinization temperature and drying simultaneously on
heated rolls like drum driers and extruders (Holm et al. 1988). Gelatinization of
starch at 120 °C for 20 min, followed by cooling to room temperature also provides
good yields of RS (Garcia-Alonso et al. 1999). High yields of SDS (39.3–56.7%)
were obtained by dual retrogradation treatment (gelatinization-retrogradationgelatinization- retrogradation) in rice starch (Tian et al. 2013). Good yields of RS3
were also obtained by various combinations of time and temperature treatments to
various sources of native starch. The temperature treatments were autoclaving the
starch at 110 °C (Berry 1986), at 121 °C (Sievert and Wursch 1993), at 127 °C
(Berry 1986), at 134 °C (Berry 1986), or at 148 °C Sievert and Pomeranz 1989) for
periods ranging from 30 min to 1 h. Recently effects of autoclaving temperature
B. A. Ashwar et al.