Molecular Structure and Some Physicochemical Properties of High‐Amylose Barley Starches

Yoshimoto, Yasushi; Tashiro, Jyunko; Takenouchi, Tadahiro; Takeda, Yasuhito

doi:10.1094/cchem.2000.77.3.279

Cited by 70 publications

(49 citation statements)

References 29 publications

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“…Very little swelling was detected with the high amylose starch (Fig. 1E) in agreement with previous findings 12,37 . It might be expected from these results that the waxy and zero amylose starches would become susceptible to enzymic degradation at a lower temperature than normal starch.…”

Section: )79087 %2( (-7'977-32supporting

confidence: 93%

Gelatinisation Characteristics and Enzyme Susceptibility of Different Types of Barley Starch in the Temperature Range 48-72°C1

MacGregor

Bazin

Izydorczyk

2002

Journal of the Institute of Brewing

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The gelatinisation temperatures, pasting characteristics and enzymic susceptibilities in the temperature range 48-72°C of normal, high amylose, low amylose and zero amylose barley starches were determined. Normal starches had the lowest gelatinisation temperatures, but low and zero amylose starches had the lowest pasting temperatures. Normal starches were the most readily soluble in water at 48-60°C in the presence of a mixture of α-amylase, β-amylase and limit dextrinase and were most readily broken down to reducing sugars by these enzymes. High amylose starch was the most resistant to enzymic hydrolysis in the temperature range 48-72°C and, hence, produced the lowest level of reducing sugars.Key words: Barley, enzymic hydrolysis, gelatinisation, high amylose, pasting, starch, waxy.-2863(9'8-32The rapid and efficient conversion of starch to fermentable carbohydrates during brewing is dependent on a number of parameters including the level of starch degrading enzymes in the malt, the gelatinisation temperature of the starch and the actual temperature program of the mash. Starch hydrolysis is carried out by a number of malt enzymes working together. These include α-amylase, β-amylase, limit dextrinase and α-glucosidase 20,21 . Although α-amylase is able to hydrolyse intact starch granules, the rate of hydrolysis is very slow compared to that of solubilised starch 27,29 . Effective hydrolysis by α-amylase, therefore, occurs only after the starch has been solubilised (or gelatinised). When this has occurred, the enzyme rapidly degrades the starch components through random hydrolysis with concomitant reduction in the viscosity of the starch solution and formation of degradation products 22 that are substrates for β-amylase action. It is this action of β-amylase that is largely responsible for the conversion of starch to the major fermentable carbohydrates, glucose, maltose and maltriose 25 . β-Amylase, however, is relatively heat labile and rapidly loses activity 28 when mashing temperatures rise over 62.5°C. It is essential, therefore, that malt starch is gelatinised at or below this temperature to permit β-amylase to complete its action before losing a significant amount of activity through heat inactivation.The preferred substrates for limit dextrinase are the branched dextrins formed from starch by the combined action of α-and β-amylases 21 . Limit dextrinase appears to have only limited action during mashing, however 10 . This is caused, probably, through inhibition by low molecular weight inhibitors in the malt 17 rather than by excessive lability at mashing temperatures 28 . α-Glucosidase may play a role during mashing by hydrolysing small maltodexrins to glucose but the importance of α-glucosidase action remains unclear 31 .Several methods have been used to measure the gelatinisation (solubilisation) temperatures of starch granules but each tends to measure a different aspect of this complex phenomenon 2,34 and so not all methods give the same result. One of the most common methods, differential scanning cal...

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Section: )79087 %2( (-7'977-32supporting

confidence: 93%

Gelatinisation Characteristics and Enzyme Susceptibility of Different Types of Barley Starch in the Temperature Range 48-72°C1

MacGregor

Bazin

Izydorczyk

2002

Journal of the Institute of Brewing

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“…Furthermore, Goami 2 has a mutant amylose extender in its endosperm and was found in our present analysis in terms of the amylopectin profile to have the highest levels of medium length chains with a DP of 13 to 24, long chains with a DP of 25 to 36 and very long chains, but the lowest levels of short chains. This result is similar to the previous findings of Yoshimoto et al (2000) who demonstrated that amylopectin molecules from high amylose starches contain a relatively high proportion of very long chain products. The study of Radhika et al (1993) on rice starch has shown that a higher level of long chain, amylopecins is associated with firmer rice after cooking and that retrogradation is also more advanced in rice with more long chain amylopectins.…”

Section: Resultssupporting

confidence: 92%

Physicochemical Characteristics of Starches in Rice Cultivars of Diverse Amylose Contents

Yoon¹,

Chun²,

Oh³

et al. 2012

Korean Journal of Crop Science

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Through the sampling four rice cultivars with differing amylose contents, the relationship between the structural and gelatinization properties of endosperm starches was analyzed. These rice varieties exhibited different chain length distribution ratio within the amylopectin cluster as well as varing amylose levels. The proportion of amylopectin short chains of in Goami cutlivars was higher than the other varieties, whereas the Goami 2 which shows amylose extender mutant properties in the endosperm showed the highest proportion of long chains. In X-ray diffraction analysis of rice starches, the Goami 2 variety displayed a B-type pattern whereas the other varieties were all A-type. Among the cultivars with high and normal rice starch levels, those with the higher amylose contents showed distinctly lower swelling. Goami 2 rice was found to have the highest onset and peak gelatinization temperature from the differential scanning calorimetry results. The four rice cultivars under analysis also showed different rates of hydrolysis by amyloglucosidase. These findings suggest that the composition and chemical structure of the starch content is a major determinant of both the gelatinization and functional properties of rice.

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“…Amylose has a molecular weight range of approximately 10 5 _10 6 g/mol (BuMon et al, 1998;Mua and Jackson, 1997), degrees of polymerization (dp) of 324-4920 monomer units and 9-20 branch points equivalent to 3-11 chains per molecule (Hizukuri, etal., 1981;MuaandJackson, 1997;Takeda et al, 1987;Wang and White, 1994;Yashushi et al, 2002;Yoshimoto et al, 2000). Each chain contains approximately 200-700 glucose residues (Tester and Karkalas, 2002).…”

Section: Major Structural Componentsmentioning

confidence: 99%

The impact of heat-moisture treatment on the molecular structure and physicochemical properties of normal and waxy potato starches

Varatharajan

Hoover

Liu

et al. 2010

Carbohydrate Polymers

151

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Heat-moisture treatment (HMT) is a physical modification technique that modifies starch structure and properties without destroying its granular structure. HMT has been shown to cause starch chain interactions and crystallite disruption/reorientation within the amorphous and crystalline domains. However, the part played by amylose (AM) during HMT of starches is not properly understood. Furthermore, a systematic study has not been carried out to examine how variations in HMT temperatures influence molecular structure, physicochemical properties and digestibility of normal potato (NP) and waxy potato (WP) starches. Thus, the objective of this study was to determine changes to molecular structure, physicochemical properties and digestibility ofNP and WP starches on HMT at different temperatures (80,100,120 and l30°C) for 16 h at 27% moisture. Structural changes on HMT were monitored by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), polarized light microscopy (pLM), wide angle X-ray scattering (WAXS), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, fluorophore assisted capillary electrophoresis (FACE) and KlS spectra. Changes to physicochemical properties on HMT were determined by granular swelling, amylose leaching, gelatinization parameters and pasting properties. Digestibility of normal and waxy potato starches before and after HMT by porcine pancreatic a-amylase (PPA) was monitored by measuring initial velocity and by exarninationofthe granular structure at different stages of hydrolysis by SEM, CLSM and PLM. The results showed that structural changes on HMT were influenced by differences in starch chain mobility at different temperatures of HMT. Starch chain mobility, in turn, was influenced by the interplay between the extent to which B-type crystallites were transformed into A+B-type crystallites, kinetic energy imparted to starch chains and amylose content. The main type of structural changes influencing physicochemical properties at different temperatures of HMT were starch chain interactions (at 80 and IOO°C), disruption of hydrogen bonds between amylose-amylopectin and amylopectin-amylopectin (at 120 and l30°C), disorganization of amylopectin chains near the vicinity of the hilum (at 100, 120 and l30°C)andformationofinterruptedhelices(atl30°C).The susceptibility ofNP and WP starches towards a-amylase decreased at 80°C, but increased in the range 100 to l30°C. NPand WPstarches exhibited heterogeneity in degradation (NP>WP) Most studies have been on the impact ofHMT on the thermal properties, crystallinity and pasting propertiesofnorrnalstarches. Some researchers (Hoover and Manuel, 1996; Kweon el al., 2000;Zavareze et al., 2010) have attempted to explain the impact of HMT on the structure and physicochemical properties of starches varying in amylose content. However, the part played by amylose during HMT of starches is still not properly understood. Unlike in cereal starches, amylose has been shown to be co-crystallized with amylopectin...

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Molecular Structure and Some Physicochemical Properties of High‐Amylose Barley Starches

Cited by 70 publications

References 29 publications

Gelatinisation Characteristics and Enzyme Susceptibility of Different Types of Barley Starch in the Temperature Range 48-72°C1

Gelatinisation Characteristics and Enzyme Susceptibility of Different Types of Barley Starch in the Temperature Range 48-72°C1

Physicochemical Characteristics of Starches in Rice Cultivars of Diverse Amylose Contents

The impact of heat-moisture treatment on the molecular structure and physicochemical properties of normal and waxy potato starches

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