Molecular Structure Of Amylopectin Research Articles

Exploration of unique starch physicochemical properties of novel buckwheat lines created by crossing Golden buckwheat and Tatary buckwheat

Buckwheat is considered as a healthy cereal food, and it is essential to cultivate new buckwheat lines with good starch physicochemical properties for both consumers and food producers. Six novel buckwheat (Duoku, Dk) were generated by crossing of Golden buckwheat and Tatary buckwheat, and their kernel appearance properties and starch physicochemical properties were analyzed together with one domestic line (Cimiqiao) and one wild line (Yeku). The results showed that Dk samples had better appearance properties than two control samples. The Dk samples showed lower amylose content, similar amylopectin molecular structure and chain length distributions, and larger starch granules compared with Cimiqiao. The digestion results showed that two Dk samples: Dk6 & Dk9 had high resistant starch content; while the other two Dk samples: Dk37 & Dk38 had a steady glucose releasing rate. The Dk samples also showed high gelatinization temperature, indicating they were good raw materials for producing glass noodle. This study proved that Dk buckwheat had unique starch physicochemical properties, and could be used as new food materials in the future.

Molecular structure of lotus seed amylopectins and their beta-limit dextrins

Investigation on amylopectin molecular structure is gaining importance for understanding starch property. Lotus seeds are a novel starch source with high apparent amylose content. Current understanding on the molecular structure of amylopectin in lotus seed starch is scarce. This study compared the molecular structure of a range of lotus seed amylopectins with those of maize and potato amylopectins. Internal structures of these amylopectins were compared via investigating the chain length distribution of their β-limit dextrins. The average lengths and molar compositions of unit chains in lotus seed amylopectins and their β-limit dextrins fell generally between those of maize and potato. The average chain lengths of lotus seed, maize, and potato amylopectins were 19.95 (on average), 19.11, and 21.19 glucosyl residues, respectively. Lotus seed amylopectins had higher weight proportion of clustered unsubstituted chains (44.94 % on average) than those of potato (43.99 %) and maize amylopectins (42.95 %). Results of correlation analysis indicated that apparent amylose content of LS was related to structural characteristics of its amylopectin due to the presence of long external chains. The results of this study are of fundamental importance for the utilization of lotus seed starch as a novel starch source.

High fructan barley lines produced by selective breeding may alter β-glucan and amylopectin molecular structure

Six cross-bred barley lines developed by a breeding strategy with the target to enhance the fructan synthesis activity and reduce the fructan hydrolysis activity were analyzed together with their parental lines, and a reference line (Gustav) to determine whether the breeding strategy also affected the content and molecular structure of amylopectin and β-glucan. The highest fructan and β-glucan content achieved in the novel barley lines was 8.6 % and 12 %, respectively (12.3-fold and 3.2-fold higher than in Gustav). The lines with low fructan synthesis activity had higher starch content, smaller building blocks in amylopectin, and smaller structural units of β-glucans than the lines with high-fructan synthesis activity. Correlation analysis confirmed that low starch content was associated with high amylose, fructan, and β-glucan content, and larger building blocks in amylopectin.

Effects of amylose and amylopectin molecular structures on starch electrospinning

The role of amylose content in electrospinning starch nanofibres is well understood, but that is not the case for the roles of the molecular structures of amylose and amylopectin. Here, correlations between starch molecular-structure parameters and electrospinnability evaluation indices (average droplet number, average bead number, and average fibre diameter) and dope properties (shear viscosity, conductivity, and surface tension) were examined. Starches with lower amounts of short amylopectin chains, higher amounts of either/or long amylopectin chains and/or lower degree of branching showed decreased viscosity of the electrospinning dopes, and resulted in a reduced average droplet number of electrospun fibre mats. The molecular sizes of amylose and whole starch, and the average degree of polymerization for amylose chains, all correlated with the shear viscosity and surface tension of dopes, and thus influenced the average fibre diameter. This expands the current understanding between amylopectin molecular structure and starch electrospinning, thereby assisting a better choice of starches for desired electrospinnability properties.

Molecular structure of amylopectin/amylose from Solanum lycocarpum starch after enzymatic hydrolysis

The fruit of Solanum lycocarpum is a rich source of starch which remains unexploited despite its promising chemical and rheological properties. In this study, the molecular structures of amylopectin and amylose from S. lycocarpum starch were evaluated by HPAEC-PAD, being determined their chain length and degree of polymerization (DP). In addition, the starch was submitted to enzymatic hydrolysis using immobilized α-amylase (PANI-AMY) and glucoamylase (PANI-GLU). The enzymes immobilization onto polyaniline-glutaraldehyde derivatives was optimized through a Central Composite Rotatable Design (CCRD) and the hydrolysis products were characterized by Thin Layer Chromatography (TLC) and HPAEC-PAD. Results showed that amylopectin from S. lycocarpum starch had a maximal DP of 86, being observed a predominance of chains with type B1 (DP 13–24). On the other hand, the amylose is composed by short chain polymers, presenting DP of 57. Results from serial hydrolysis evidenced that the PANI-AMY reactor produced a set of malto-oligosaccharides, with predominance of pentoses (348.11 μg mL−1), while in the PANI-GLU reactor it was produced high levels of glucose. In addition, hydrolysis tests using high starch concentration (10% w/v) evidenced that the reactors can be efficiently used to hydrolyze starch at the similar concentration to that used in industrial processes, being able to efficiently produce starch liquefaction. Therefore, the results obtained in this work contribute to improve the information about the properties and potentialities of native and hydrolyzed starches from S. lycocarpum.

Distribution of short to medium amylose chains are major controllers of in vitro digestion of retrograded rice starch

In many cultures, rice is let to cool for a while after cooking before being consumed, which results in some retrogradation of the starch. The in vitro digestibility of 16 cooked rice starches after extended cold (4 °C) storage, which leads to extensive retrogradation, was investigated from the perspective of their starch molecular fine structure. Size-exclusion chromatography (SEC) and fluorophore-assisted carbohydrate electrophoresis (FACE) were used to characterize the starch chain-length distributions (CLDs) and whole molecular size distributions. The retrograded starch gel network was studied by differential scanning calorimetry and scanning electron microscopy. Pearson correlation analysis with in vitro digestibility revealed that the starch digestion rate was positively correlated with cell size and cell wall thickness within the formed gel network, which was mainly derived from the interactions of amylose short-medium chains and not strongly related to amylopectin molecular structure. This suggests that rather than just altering amylose content, modification of amylose fine molecular structure (e.g. increasing the amount of short-medium amylose chains) can also slow rice starch digestibility.

Properties and Digestibility of Octenyl Succinic Anhydride-Modified Japonica-Type Waxy and Non-Waxy Rice Starches.

Waxy and non-waxy rice starches from japonica type Korean rice varieties were esterified with different levels of octenyl succinic anhydride (OSA), and the molecular structure of amylopectin (AP), digestibility, and emulsion stability were investigated. As OSA levels increased, the degree of substitution, granule size, peak and final viscosities, emulsion stability, and short chain of AP increased. However, the gelatinization temperature and enthalpy, and digestibility decreased. All OSA esterified starches showed a new band at 1723 cm−1, but maintained A-type crystallinity. The DP6-12 of AP in waxy rice starch (WRS) was higher than that in non-waxy rice starch (NRS) with increasing OSA levels. Because the amylose and long chain of AP accessed easily with OSA groups, the digestibility of NRS was lower than that of WRS. The emulsion stability was higher in WRS than in NRS. From the above results, it is suggested that amylose should have a higher affinity with OSA esterification than AP and that the emulsion stability should increase in WRS, but the digestibility should decrease in NRS after OSA modification.

고아밀로스 쌀 품종 전분의 분자구조적, 열적특성 및 유화제 첨가에 의한 아밀로스-지질 복합체 형성

Purpose: The present study assessed molecular structural and thermal properties of rice starches with high amylose content and their ability to form amylose-lipid complexes with various emulsifiers. Methods: Rice starches from four cultivars (Dodamssal, Bukkyoung, Saegoami, and Saemimyeon) were analyzed for amylose and amylopectin molecular structure using high performance liquid chromatography (HPLC), thermal properties, amylose-lipid complex formation with various emulsifiers using differential scanning calorimeter (DSC), and in vitro starch digestibility. Results: Among the four starches, Dodamssal, which has significantly higher amylose content and longer branched chains of amylopectin than the other three starches, showed significantly different thermal properties, amylose-lipid complex formation, starch digestibility based on high starch pasting and gelatinization temperature, high amylose-lipid complex dissociation enthalpy, and high resistant starch content. Bukkyoung and Saegoami were not significantly different molecular structure and exhibited similar thermal characteristics, amylose-lipid complex formation, and starch digestibility. Conclusion: Differences in the molecular structures of amylose and amylopectin for the four starches significantly influenced the starch pasting and gelatinization characteristics, the amylose-lipid complex formation by various emulsifiers, and the in vitro starch digestibility. Dodamssal could be a potential source for effective amylose-lipid complex formation, which may contribute to enhancing type 5 RS.

Shear-thickening behavior of gelatinized waxy starch dispersions promoted by the starch molecular characteristics

An unusual shear-thickening behavior was observed in 10% w/w gelatinized waxy potato and waxy corn starch dispersions at shear rates around 20 s−1. However, the phenomenon was not found in gelatinized dispersions of waxy rice. The aim of this study was to investigate reasons for the observed shear-thickening behavior as well as its relationship with the amylopectin molecular structure. This unique phenomenon only appears at a shear rate of about 20 s−1 during the increasing shear rate stage of the first cycle of a two-cycle steady shear flow test. After 7 d storage, the shear-thickening behavior of waxy potato starch dispersions disappeared, while it remained in waxy corn starch dispersions. A small strain temperature sweep test applied to waxy potato starch dispersions stored for 7 d showed a significant increase in the elastic behavior of dispersions at temperatures lower than 60 °C. This behavior was not observed on fresh and 7 d stored waxy corn and waxy rice dispersions. The study provides valuable information on a unique rheological behavior of waxy starch dispersions and its relationship to the amylopectin structure, thus opening opportunities for the design of novel foods with desired nutritional and textural properties.

Effects of different Wx alleles on amylopectin molecular structure and enzymatic hydrolysis properties of rice starch

ABSTRACTAllelic variation at the Wx locus plays a vital role in regulating apparent amylose content (AAC) as well as other important starch properties in rice grain. However, the extent of Wx allelic variation affecting amylopectin fine structure and enzymatic hydrolysis properties of rice starch remains unknown. In this paper, a series of rice single-segment substitution lines with five different Wx alleles (wx, Wxt, Wxg1, Wxg2 and Wxg3) were used for comparative studies. The results showed that the five Wx alleles exhibited a wide variation in amylopectin molecular structure, hydrolysis and in vitro digestion properties of rice starch. Amylopectin chain length distribution as evaluated by fluorophore-assisted capillary electrophoresis was significantly different for the five Wx alleles, which might result in different functional properties. The hydrolysis degree of the five Wx genotype starches by α-amylase or amyloglucocidase was in the order wx > Wxt > Wxg1 > Wxg3 > Wxg2. The rapidly digestible starch (RDS) content of the tested rice starches followed the order wx = Wxg3 > Wxt = Wxg1 > Wxg2. The extent decrease of slowly digestible starch (SDS) content was wx = Wxt > Wxg1 > Wxg2 > Wxg3, while the trend in resistant starch (RS) content was Wxg2 > Wxg3 > Wxg1 > Wxt > wx. Correlation analysis indicated that AAC was significantly positively correlated with RS but significantly negatively correlated with SDS and hydrolysis. The RDS showed a significant positive correlation with amylopectin short chains (DP 6–12) but no significant correlations with other structural properties. The present results could provide important information for the application of rice starches with different Wx genotypes.

Effect of microwave irradiation on internal molecular structure and physical properties of waxy maize starch

Native waxy maize starch was treated at a moisture content of 30% by microwave irradiation for 5 min, 10 min and 20 min, respectively. The molecular structure and physical properties of waxy maize starch were characterized. Compared with native maize starch, lower population of short chains of amylopectin (A chain), higher proportion of short B1 and long B2 and B3 were observed in irradiated starches. 1H NMR data showed that α-(1,6) glycosidic linkages were destroyed more easily than α-(1,4) glycosidic linkages during microwave treatment. A increase in gelatinization temperatures and a decrease in the molecular weight, the relative crystallinity, ΔH, viscosities and syneresis were observed after microwave treatment. Gelatinization temperatures were positively correlated with long chains B3 with DP > 36, while ΔH and syneresis were negatively correlated with them. The extent of the changes induced by microwave treatment for different times revealed that the major degradation occurred in internal chain (amorphous region) at the first stage (microwave treatment for 5 min), the external chain (crystalline region) mostly destroyed at the second stage (microwave treatment for above 10 min). The foregoing data indicated that the molecular structure of amylopectin is a critical factor determining physical properties.

Amylopectin molecular structure in relation to physicochemical properties of quinoa starch

Structure-function relationships of starch components remain a subject of research interest. Quinoa starch has very small granules (∼2μm) with unique properties. In this study, nine quinoa starches varied greatly in composition, structure, and physicochemical properties were selected for the analysis of structure-function relationships. Pearson correlation analysis revealed that the properties related to gelatinization such as swelling power, water solubility index, crystallinity, pasting, and thermal properties are much affected by the amylopectin chain profile and amylose content. The parameters of gel texture and amylose leaching are much related to amylopectin internal structure. Other properties such as enzyme susceptibility and particle size distribution are also strongly correlated with starch composition and amylopectin structure. Interesting findings indicate the importance of amylopectin internal structure and individual unit chain profile in determining the physicochemical properties of starch. This work highlights some relationships among composition, amylopectin structure and physicochemical properties of quinoa starch.

Molecular structure of quinoa starch

Quinoa starch has very small granules with unique properties. However, the molecular structure of quinoa starch remains largely unknown. In this study, composition and amylopectin molecular structure of 9 quinoa starch samples were characterised by chromatographic techniques. In particular, the amylopectin internal molecular structure, represented by φ, β-limit dextrins (LDs), was explored. Great variations in the composition and molecular structures were recorded among samples. Compared with other amylopectins, quinoa amylopectin showed a high ratio of short chain to long chains (mean:14.6) and a high percentage of fingerprint A-chains (Afp) (mean:10.4%). The average chain length, external chain length, and internal chain length of quinoa amylopectin were 16.6, 10.6, and 5.00 glucosyl residues, respectively. Pearson correlation and principal component analysis revealed some inherent correlations among structural parameters and a similarity of different samples. Overall, quinoa amylopectins are structurally similar to that from starches with A-type polymorph such as oat and amaranth starches.

Effects of ripening temperature on starch structure and gelatinization, pasting, and cooking properties in rice (Oryza sativa).

The effect of ripening temperature on rice (Oryza sativa) grain quality was evaluated by assessing starch structure and gelatinization, pasting, and cooking properties. As the ripening temperature increased, the amylose content and number of short amylopectin chains decreased, whereas intermediate amylopectin chains increased, resulting in higher gelatinization temperatures and enthalpy in the starch. These results suggested that an increase in cooking temperature and time would be required for rice grown at higher temperatures. A high ripening temperature increased the peak, trough, and final viscosities and decreased the setback due to the reduction in amylose and the increase in long amylopectin chains. With regard to starch crystallinity and amylopectin molecular structure, the highest branches and compactness were observed at 28/20 °C. Rice that was grown at temperatures above 28/20 °C showed a deterioration of cooking quality and a tendency toward decreased palatability in sensory tests.

How is the assembly of crystalline lamella influenced by the molecular structure of amylopectin?

How is the assembly of crystalline lamella influenced by the molecular structure of amylopectin?

Amylopectin structure of heat–moisture treated starches

AbstractThe effects of heat–moisture treatment (HMT; moisture content of 25%, at 100°C for 24 h) on starch chain distribution and unit chain distribution of amylopectin in normal rice, waxy rice, normal corn, waxy corn, normal potato, and waxy potato starches were investigated. After HMT, starch chain distribution (amylose and amylopectin responses) of waxy corn and potato starches were identical to those of untreated starches, whereas the chromatographic response of waxy rice starch showed a slight decrease, but with a slight increase in peak tailing. This result indicated that HMT had no (or very limited) effect on the degradation of amylopectins. Analysis of unit chain distribution of amylopectins revealed that waxy characteristics affected the molecular structure of amylopectin in untreated starches, i.e., the CL of normal‐type starches was greater than that of waxy‐type starches. After HMT, the CL and unit chain distribution of all starches were no different than those of untreated starches. The results implied that changes in the physico‐chemical properties of HMT starches would be due to other phenomena rather than the degradation of amylopectin molecular structure. However, the thermal degradation of amylopectin molecules of waxy starches could occur by HMT at higher treatment temperatures (120 and 140°C).

Amylopectin molecular structure and functional properties of starch from three Ugandan cassava varieties

Amylopectin molecular structure is a very important determinant of starch functional properties. The main purpose of this study was to determine the strength of the relationship between the amylopectin structure of starches from cassava varieties and their functional properties. TME14 had the highest (46.63%) proportion of A chains while Bamunanika had the lowest 42.27%. Bamunanika had the highest (23.33%) proportion of B3+ chains while TME14 had the lowest 19.66%. TME14 had the highest amylopectin molecular weight 2.74x108 g/mol while NASE10 had the lowest 2.42x108 g/mol. TME14 had a higher gelatinisation temperature 65.37°C compared to the other varieties. Bamunanika had the highest final viscosity 2477.66 mPa s while NASE10 had the highest set back viscosity (494.50 mPa s). TME14 had the highest pasting temperature 67.80°C while NASE10 had the lowest 65.23°C. There was a significant negative correlation between final viscosity and A chains (r = -0.64), pasting temperature and A chains (r = - 0.77), A, B1 chains and gelatinisation temperature of retrograded starches (r = - 0.82, r = - 0.87), respectively, gyration radius and onset temperature of gelatinisation for the retrograded starch (r = -0.56) and a significant positive correlation between B2 chains and pasting temperature (r = 0.94), amylopectin molecular weight and percentage retrogradation (r = 0.66). These findings revealed possible improvement through breeding for starch with desired qualities. Key words: Amylopectin structure, cassava varieties, functional properties.

Study on molecular structure and hydration mechanism of Domyoji-ko starch by IR and NIR hetero 2D analysis

The hydration structure of starch molecule in Domyoji-ko, which is made from gluey rice, was investigated by hetero 2D correlation analysis of IR and NIR spectroscopy. The feature near 1020 cm −1 in the IR spectra of Domyoji-ko is changed by rehydration process, indicating that the molecular structure of amylopectin in the starch has been varied by the hydration without heating. The intensity of a band at 4770 cm −1 in NIR spectra is decreasing with the increasing of either the heating time with water or rehydration time without heating. These results suggest that the hydration of Domyoji-ko has proceeded in similar mechanisms on these processes. The generalized hetero 2D IR-NIR correlation analysis for rehydration of Domyoji-ko has supported the assignments for NIR bands concerning the gelatinization of starch.

北海道米の食味に関与するアミロペクチン分子の構造解析に関する研究

北海道米の食味に関与するアミロペクチン分子の構造解析に関する研究

Molecular structure of amylopectin from amaranth starch and its effect on physicochemical properties

The molecular structure of amylopectin and its ϕ,β-limit dextrins from starch of 13 amaranth cultivars was determined by HPAEC-PAD after debranching. Chain length profiles of amylopectins showed bimodal distributions. The molar-based ratios of the average chain lengths of amylopectins (CL ap) ranged from 17.41 to 18.22. The molar-based average chain lengths (CL ld) and average B-chain lengths (BCL ld) of ϕ,β-limit dextrins varied from 7.68 to 8.05, and from 14.10 to 14.73, respectively. Correlation analysis indicated that most structural parameters were positively correlated with thermal properties with few exceptions, whereas the content of fraction fa′ (“′” stands for molar-based chain length ratio) was negatively correlated with the thermal properties. Pasting properties of cold paste viscosity (CPV) and setback were also correlated with amylopectin structural parameters.