25
digestion property through the partial shortening of amylopectin A and B1 exterior
chains, as well as linear chains of amylose, through the action of β-amylase and
maltogenic α-amylase (Ao et al. 2007). This correlated closely with an increase in
the number of α-1, 6 linkages and a simultaneous decrease in the number of α-1, 4
linkages. The enzyme-treated starch consists of B- and V-type crystalline structures,
which increases the resistance of starch to digestion. These studies suggested that
enzymatic debranching of the exterior chains of amylopectin molecule can change
its structure and form higher proportions of SDS and RS.
Chemical Modifications
In many processes, starch is being modified by chemical reagents to improve functionality and create commercially valuable, starch based products. The most common chemical treatments are acid treatment, oxidation, cross-linking and substitution
including esterification and etherification. Recently studies have focused on such
treatments in SDS and RS production (Zhao et al. 2012; Ashwar et al. 2016; Ashwar
et al. 2018). The enzymatic resistance in RS4 is done by cross linking with chemical
agents (Haynes et al. 2000). Cross linked starches are obtained by reaction of starch
with bi- or polyfunctional reagents like phosphorus oxychloride, sodium trimetaphosphate, or mixed anhydrides of acetic acid and dicarboxylic acids like adipic
acid. Cross-linking of rice, wheat, corn, potato, tapioca, oat and mung bean starches
using sodium trimetaphosphate (STMP), sodium tripolyphosphate (STPP), epichlorohydrin or phosphoryl chloride (POCl 3 ), produced type 4 resistant starch (Seib and
Woo 1999; Zhao et al. 2012). These authors explained that the levels of RS in wheat
starch cross-linked with 2% POCl 3 , 12% STMP/STPP, and 2% epichlorohydrin
were 85.6, 75.6 and 75.8 g/100 g starch, respectively. Sang et al. (2010) prepared
phosphorylated wheat starch with high levels of the RS (68.7%) and SDS (24.4%).
Cross-linking when carried out by sulphonate and phosphate groups between starch
molecules through their hydroxyl groups brings resistance to enzymatic hydrolysis
(Hamilton and Paschall 1967). Cross-linking of starch with mixtures of STMP and
STPP under alkaline conditions restricts swelling of starch and imparts increasing
resistance to digestive enzymes (Woo and Seib 2002). Simsek et al. (2012) prepared
acetylated bean starch with high levels of the RS (44%). Acetylation of starch
increased the RS content in bean, as a result of acetyl groups which blocks the
action of digestive enzymes (Chung et al. 2008). Modification of starch with octenyl
succinic anhydride is known to increase levels of SDS and RS more than other
modifications such as acetylation, hydroxypropylation, or crosslinking (Han and
BeMiller 2007; Juansang et al. 2012). Esterification with octenyl succinic anhydride
(OSA) has been shown to be the most potent method of modifying waxy starch to
form SDS, followed by combined modifications like crosslinkinghydroxypropylation, acetylation and crosslinking (Han and BeMiller 2007). The
modified starch with attached OSA molecules may act as uncompetitive inhibitors
to reduce the enzyme activity and thereby cause slow digestion of starch. As these
Resistant Starch and Slowly Digestible Starch
digestion property through the partial shortening of amylopectin A and B1 exterior
chains, as well as linear chains of amylose, through the action of β-amylase and
maltogenic α-amylase (Ao et al. 2007). This correlated closely with an increase in
the number of α-1, 6 linkages and a simultaneous decrease in the number of α-1, 4
linkages. The enzyme-treated starch consists of B- and V-type crystalline structures,
which increases the resistance of starch to digestion. These studies suggested that
enzymatic debranching of the exterior chains of amylopectin molecule can change
its structure and form higher proportions of SDS and RS.
Chemical Modifications
In many processes, starch is being modified by chemical reagents to improve functionality and create commercially valuable, starch based products. The most common chemical treatments are acid treatment, oxidation, cross-linking and substitution
including esterification and etherification. Recently studies have focused on such
treatments in SDS and RS production (Zhao et al. 2012; Ashwar et al. 2016; Ashwar
et al. 2018). The enzymatic resistance in RS4 is done by cross linking with chemical
agents (Haynes et al. 2000). Cross linked starches are obtained by reaction of starch
with bi- or polyfunctional reagents like phosphorus oxychloride, sodium trimetaphosphate, or mixed anhydrides of acetic acid and dicarboxylic acids like adipic
acid. Cross-linking of rice, wheat, corn, potato, tapioca, oat and mung bean starches
using sodium trimetaphosphate (STMP), sodium tripolyphosphate (STPP), epichlorohydrin or phosphoryl chloride (POCl 3 ), produced type 4 resistant starch (Seib and
Woo 1999; Zhao et al. 2012). These authors explained that the levels of RS in wheat
starch cross-linked with 2% POCl 3 , 12% STMP/STPP, and 2% epichlorohydrin
were 85.6, 75.6 and 75.8 g/100 g starch, respectively. Sang et al. (2010) prepared
phosphorylated wheat starch with high levels of the RS (68.7%) and SDS (24.4%).
Cross-linking when carried out by sulphonate and phosphate groups between starch
molecules through their hydroxyl groups brings resistance to enzymatic hydrolysis
(Hamilton and Paschall 1967). Cross-linking of starch with mixtures of STMP and
STPP under alkaline conditions restricts swelling of starch and imparts increasing
resistance to digestive enzymes (Woo and Seib 2002). Simsek et al. (2012) prepared
acetylated bean starch with high levels of the RS (44%). Acetylation of starch
increased the RS content in bean, as a result of acetyl groups which blocks the
action of digestive enzymes (Chung et al. 2008). Modification of starch with octenyl
succinic anhydride is known to increase levels of SDS and RS more than other
modifications such as acetylation, hydroxypropylation, or crosslinking (Han and
BeMiller 2007; Juansang et al. 2012). Esterification with octenyl succinic anhydride
(OSA) has been shown to be the most potent method of modifying waxy starch to
form SDS, followed by combined modifications like crosslinkinghydroxypropylation, acetylation and crosslinking (Han and BeMiller 2007). The
modified starch with attached OSA molecules may act as uncompetitive inhibitors
to reduce the enzyme activity and thereby cause slow digestion of starch. As these
Resistant Starch and Slowly Digestible Starch