29
more slowly digested than unheated samples. Severijnen et al. (2007) used these
principles to study the production of a sterilized liquid product with a low GI. When
the modified high amylose starch was heated above 120
°
C for 4–5 min., the SDS
content increased and reached a maximum, where it remains stable for several
months when stored at 4 °C. According to Woortman and Steeneken (2004), high
SDS content was achieved when a starch product with an amylose content of below
50% was heated to at least 170 °C under mild acidic conditions, followed by rapid
cooling. High amylose starch is rich source of RS2 (Berry 1986), which after heating and cooling gives RS3 in high yields (Sievert and Pomeranz 1989) or retrograded starch (Englyst et al. 1992). Retrograded amylose in wheat, maize, peas and
potatoes was found to be highly resistant to digestion (Ring et al. 1988). Park et al.
(2009) reported that temperature cycled storage increased the formation of resistant
starch and reduced the GI (glycemic index) of waxy corn starch. Borczak et al.
(2014) claimed that prolonged frozen storage of wheat-flour rolls significantly
increased RS formation. Dual-retrogradation treatment was more efficient as compared to single retrogradation (Tian et al. 2013). Repeated autoclaving of wheat
starch increased the RS upto 10%. Retrogradation of amylose was recognized as the
main factor for the formation of RS and higher amounts were obtained with repeated
autoclaving (Dundar and Gocmen 2013; Bjorck et al. 1990). On storage, gelatinized
starch pastes undergo retrogradation to semicrystalline structure that resists enzymatic digestion. Wheat bread and corn flakes are rich sources of this type of RS
where as cooked and cooled potatoes have only 25% of RS3 (retrograded starch)
(Englyst and Cummings 1985).
Interactions of Starch with Other Components
Interactions of starch with other food components are known to influence the formation of SDS or RS. Two important types of starch interaction with other components
involve formation of starch-lipid complexes and starch-protein interactions.
Interaction of starch with the protein is thought to reduce the rate of α-amylolysis of
starch in cereal and legume products (Wursch et al. 1986; Jenkins et al. 1987;
Colonna et al. 1990; Biliaderis 1991). According to Granfeldt and Bjorck (1991), a
dense and viscoelastic gluten network surrounds the starch granules in pasta products which restricts the swelling and leaching of starch molecules during boiling
and also reduces the access of enzymes to the starch. The interaction of starch with
protein also limited the glycemic response of starch in white bread made from regular flour, while gluten-free bread showed a higher glycemic and insulinemic response
(Jenkins et al. 1987). In another study, mixture of potato starch and albumin protein
was autoclaved and then cooled to −20 °C, and effect of albumin on digestibility of
potato starch was studied. It was found that added albumin reduced the content of
resistant starch (Escarpa et al. 1997). In a study by Holm et al. (1983), it was claimed
that amylose molecules formed complexes with lysolecithin, and these complexes
were degraded slowly and were completely absorbed in the GI tract of rats within
Resistant Starch and Slowly Digestible Starch
more slowly digested than unheated samples. Severijnen et al. (2007) used these
principles to study the production of a sterilized liquid product with a low GI. When
the modified high amylose starch was heated above 120
°
C for 4–5 min., the SDS
content increased and reached a maximum, where it remains stable for several
months when stored at 4 °C. According to Woortman and Steeneken (2004), high
SDS content was achieved when a starch product with an amylose content of below
50% was heated to at least 170 °C under mild acidic conditions, followed by rapid
cooling. High amylose starch is rich source of RS2 (Berry 1986), which after heating and cooling gives RS3 in high yields (Sievert and Pomeranz 1989) or retrograded starch (Englyst et al. 1992). Retrograded amylose in wheat, maize, peas and
potatoes was found to be highly resistant to digestion (Ring et al. 1988). Park et al.
(2009) reported that temperature cycled storage increased the formation of resistant
starch and reduced the GI (glycemic index) of waxy corn starch. Borczak et al.
(2014) claimed that prolonged frozen storage of wheat-flour rolls significantly
increased RS formation. Dual-retrogradation treatment was more efficient as compared to single retrogradation (Tian et al. 2013). Repeated autoclaving of wheat
starch increased the RS upto 10%. Retrogradation of amylose was recognized as the
main factor for the formation of RS and higher amounts were obtained with repeated
autoclaving (Dundar and Gocmen 2013; Bjorck et al. 1990). On storage, gelatinized
starch pastes undergo retrogradation to semicrystalline structure that resists enzymatic digestion. Wheat bread and corn flakes are rich sources of this type of RS
where as cooked and cooled potatoes have only 25% of RS3 (retrograded starch)
(Englyst and Cummings 1985).
Interactions of Starch with Other Components
Interactions of starch with other food components are known to influence the formation of SDS or RS. Two important types of starch interaction with other components
involve formation of starch-lipid complexes and starch-protein interactions.
Interaction of starch with the protein is thought to reduce the rate of α-amylolysis of
starch in cereal and legume products (Wursch et al. 1986; Jenkins et al. 1987;
Colonna et al. 1990; Biliaderis 1991). According to Granfeldt and Bjorck (1991), a
dense and viscoelastic gluten network surrounds the starch granules in pasta products which restricts the swelling and leaching of starch molecules during boiling
and also reduces the access of enzymes to the starch. The interaction of starch with
protein also limited the glycemic response of starch in white bread made from regular flour, while gluten-free bread showed a higher glycemic and insulinemic response
(Jenkins et al. 1987). In another study, mixture of potato starch and albumin protein
was autoclaved and then cooled to −20 °C, and effect of albumin on digestibility of
potato starch was studied. It was found that added albumin reduced the content of
resistant starch (Escarpa et al. 1997). In a study by Holm et al. (1983), it was claimed
that amylose molecules formed complexes with lysolecithin, and these complexes
were degraded slowly and were completely absorbed in the GI tract of rats within
Resistant Starch and Slowly Digestible Starch