Interaction between sorghum endosperm proteins (kafirins), which are mainly formed by intermolecular disulphide cross-linking (Chandrashekar and Mazhar 1999) and starch granules has been studied extensively as a main factor that influences sorghum starch digestibility (Ezeogu and others 2008; Taylor and Emmambux 2010). Ezeogu and others (2005) found that cooking sorghum flour in the presence of a reducing agent (2-mercaptoethanol) improved flour starch digestibility by preventing or reducing disulphide-bonded polymerization of the kafirins, suggesting that sorghum proteins may act as a physical block to starch digestion.
In contrast to the results obtained in the present study, Austin and others (2012) found increase in starch digestibility of soft and hard sorghum endosperm porridges with the addition of anthocyanin-rich black sorghum bran. However, in the current study, whole grain sorghum flour was used instead of bran. Sorghum bran has been shown to contain mainly insoluble fiber (Gordon 2001) while whole grain sorghum flour also contains soluble fiber which in comparison to insoluble fiber has the ability to decrease enzyme accessibility to food in the small intestine by delaying gastric emptying due to its higher viscosity and gel forming properties (Pi-Sunyer 2002). The decrease in starch digestibility of sorghum-containing pastas may also be attributed to the inhibitory effect of sorghum polyphenolics on digestive enzyme activity (Mkandawire and others 2013) and interaction of sorghum polyphenolics with starch molecules (Barros and others 2012). The RDS values found in 40% RSF or 40% WSF pasta in the present study were lower than those reported in flat bread incorporating RSF or WSF at the same level (Yousif and others 2012). These differences could be attributed to the more compact structure of pasta, which is responsible for the reduced enzymatic susceptibility of starch in pasta. On the other hand the open structure of flat bread allows high accessibility to starch hydrolysis enzymes, resulting in high levels of RDS (Cavallero and others 2002). Given the relation between in vitro and in vivo starch digestion rates (Vonk and others 2000), it would be anticipated that the addition of sorghum flour into pasta would lower its glycemic index
โต้ตอบระหว่างข้าวฟ่างเอนโดสเปิร์มโปรตีน (kafirins), ซึ่งส่วนใหญ่ได้ก่อตั้งขึ้น โดย intermolecular disulphide cross-linking (Chandrashekar และ Mazhar 1999) และเม็ดแป้ง มีการศึกษาอย่างกว้างขวางเป็นปัจจัยหลักที่มีผลต่อแป้งข้าวฟ่าง digestibility (Ezeogu และอื่น ๆ 2008 เทย์เลอร์ก Emmambux 2010) Ezeogu และคนอื่น ๆ (2005) พบว่า อาหารแป้งข้าวฟ่างในต่อหน้าของตัวแทนลดลง (2 mercaptoethanol) ปรับปรุง digestibility แป้งแป้ง โดยการป้องกัน หรือลดการถูกผูกมัด disulphide polymerization ของ kafirins แนะนำว่า โปรตีนข้าวฟ่างอาจทำหน้าที่เป็นบล็อคจริงเพื่อย่อยอาหารแป้งIn contrast to the results obtained in the present study, Austin and others (2012) found increase in starch digestibility of soft and hard sorghum endosperm porridges with the addition of anthocyanin-rich black sorghum bran. However, in the current study, whole grain sorghum flour was used instead of bran. Sorghum bran has been shown to contain mainly insoluble fiber (Gordon 2001) while whole grain sorghum flour also contains soluble fiber which in comparison to insoluble fiber has the ability to decrease enzyme accessibility to food in the small intestine by delaying gastric emptying due to its higher viscosity and gel forming properties (Pi-Sunyer 2002). The decrease in starch digestibility of sorghum-containing pastas may also be attributed to the inhibitory effect of sorghum polyphenolics on digestive enzyme activity (Mkandawire and others 2013) and interaction of sorghum polyphenolics with starch molecules (Barros and others 2012). The RDS values found in 40% RSF or 40% WSF pasta in the present study were lower than those reported in flat bread incorporating RSF or WSF at the same level (Yousif and others 2012). These differences could be attributed to the more compact structure of pasta, which is responsible for the reduced enzymatic susceptibility of starch in pasta. On the other hand the open structure of flat bread allows high accessibility to starch hydrolysis enzymes, resulting in high levels of RDS (Cavallero and others 2002). Given the relation between in vitro and in vivo starch digestion rates (Vonk and others 2000), it would be anticipated that the addition of sorghum flour into pasta would lower its glycemic index
การแปล กรุณารอสักครู่..
