31
Processing Conditions
Processing/cooking, post processing and storage conditions (retrogradation) influence the formation of SDS and RS in food. This fact is of great concern for the food
industry, since it offers the possibility of increasing the SDS and RS contents of
processed foods and foodstuffs. Autoclaving, pressure-cooking, baking, flaking and
parboiling, among other methods, are known to influence the starch digestibility
and the yield of RS and SDS (Brand et al. 1985; Holm et al. 1985; Casiraghi et al.
1993; Kingman and Englyst 1994; Ashwar et al. 2016; Ashwar et al. 2017). Holm
et al. (1985) demonstrated that starch in flaked whole grained wheat was more resistant to digestion than that in boiled, steam-cooked and popped wheat during in vitro
assay. In a study of Casiraghi et al. (1993), both parboiled and quick cooking parboiled rice were digested more slowly with a lower GI than polished rice, which was
related to the availability of starch for α-amylase. Autoclaving of red kidney beans
has been shown to increase the blood glucose and insulin response as compared to
boiling at atmospheric pressure, and this may be due to thermal or mechanical alteration of the structure of seeds and may also be related to the release of physically
inaccessible starch due to mechanical disruption of cell walls (Tovar et al. 1992).
Granfeldt et al. (2000) reported that thick rolled oats cause lower glycemic responses
than thin flakes or reference bread. Boiling and pressure-cooking significantly
decreased the SDS content in three Doongara, Inga and Japonica varieties of rice
and the amylose content affected starch digestibility, which has been attributed to
the retrogradation process (Sagum and Arcot 2000). According to Guraya et al.
(2001a), when 10% waxy and nonwaxy starch suspensions were debranched with
pullulanase, followed by heating and cooling treatments to allow the crystallization
or gelling to occur, the digestibility decreased because of the formation of crystalline structures or double helices. During pullulanase debranching and retrogradation treatments of the cooked waxy maize starch suspensions, short-term
retrogradation have occurred as a result of gelation and crystallization of amylose
molecules, leading to the formation of SDS; in contrast, long-term retrogradation
occurs during storage of starch gels due to the amylopectin molecules (Miao
et al. 2009).
Determination of Resistant Starch and Slowly Digestible
Starch
Different methods have been developed for the determination of RS with significant
differences in sample preparation, enzymes used, and the establishment of experimental conditions that mimic gastrointestinal environment. Most of the methods are
employed for the determination of total RS, but some specific methods have been
developed for the quantification of RS1, RS2 and RS3.
Resistant Starch and Slowly Digestible Starch
Processing Conditions
Processing/cooking, post processing and storage conditions (retrogradation) influence the formation of SDS and RS in food. This fact is of great concern for the food
industry, since it offers the possibility of increasing the SDS and RS contents of
processed foods and foodstuffs. Autoclaving, pressure-cooking, baking, flaking and
parboiling, among other methods, are known to influence the starch digestibility
and the yield of RS and SDS (Brand et al. 1985; Holm et al. 1985; Casiraghi et al.
1993; Kingman and Englyst 1994; Ashwar et al. 2016; Ashwar et al. 2017). Holm
et al. (1985) demonstrated that starch in flaked whole grained wheat was more resistant to digestion than that in boiled, steam-cooked and popped wheat during in vitro
assay. In a study of Casiraghi et al. (1993), both parboiled and quick cooking parboiled rice were digested more slowly with a lower GI than polished rice, which was
related to the availability of starch for α-amylase. Autoclaving of red kidney beans
has been shown to increase the blood glucose and insulin response as compared to
boiling at atmospheric pressure, and this may be due to thermal or mechanical alteration of the structure of seeds and may also be related to the release of physically
inaccessible starch due to mechanical disruption of cell walls (Tovar et al. 1992).
Granfeldt et al. (2000) reported that thick rolled oats cause lower glycemic responses
than thin flakes or reference bread. Boiling and pressure-cooking significantly
decreased the SDS content in three Doongara, Inga and Japonica varieties of rice
and the amylose content affected starch digestibility, which has been attributed to
the retrogradation process (Sagum and Arcot 2000). According to Guraya et al.
(2001a), when 10% waxy and nonwaxy starch suspensions were debranched with
pullulanase, followed by heating and cooling treatments to allow the crystallization
or gelling to occur, the digestibility decreased because of the formation of crystalline structures or double helices. During pullulanase debranching and retrogradation treatments of the cooked waxy maize starch suspensions, short-term
retrogradation have occurred as a result of gelation and crystallization of amylose
molecules, leading to the formation of SDS; in contrast, long-term retrogradation
occurs during storage of starch gels due to the amylopectin molecules (Miao
et al. 2009).
Determination of Resistant Starch and Slowly Digestible
Starch
Different methods have been developed for the determination of RS with significant
differences in sample preparation, enzymes used, and the establishment of experimental conditions that mimic gastrointestinal environment. Most of the methods are
employed for the determination of total RS, but some specific methods have been
developed for the quantification of RS1, RS2 and RS3.
Resistant Starch and Slowly Digestible Starch