Debranched Starch Research Articles

Structural transformation of crystallized debranched cassava starch during dual hydrothermal treatment in relation to enzyme digestibility

Structural transformation of crystallized debranched cassava starch prepared by temperature cycling (TC) treatment and then subjected to annealing (ANN), heat-moisture treatment (HMT) and dual hydrothermal treatments of ANN and HMT was investigated. The relative crystallinity, lateral crystal size, melting temperature and resistant starch (RS) content increased for all hydrothermally treated samples, but the slowly digestible starch (SDS) content decreased. The RS content followed the order: HMT → ANN > HMT > ANN → HMT > ANN > TC, respectively. The HMT → ANN sample showed a larger lateral crystal size with more homogeneity, whereas the ANN → HMT sample had a smaller lateral crystal size with a higher melting temperature. After cooking at 50% moisture, the increased RS content of samples was observed, particularly for the ANN → HMT sample. These results suggest that structural changes of crystallized debranched starch during hydrothermal treatments depend on initial crystalline characteristics and treatment sequences, influencing thermal stability, enzyme digestibility, and cooking stability.

Acetylated debranched rice starch: Structure, characterization, and functional properties

ABSTRACTCombining biological and chemical methods for the modification of starch is a very interesting prospect. The goal of this work was to investigate the influence of debranching and acetylation on the structure of rice starch (RS), ultimately to improve the function of RS. Our experimental results showed that RS particles can be completely destroyed by debranching. The crystal structure of RS is A-type, but the structure of debranched rice starch (DRS) and acetylated debranched rice starch (ADRS) is B-type. The crystallinity degree of DRS and ADRS was less than that of RS. The surface of DRS and ADRS particles became very rough, marking a complete departure from the surface of smooth RS granules. Acetylation occurred specifically at the sides of DRS granules. The surface hydroxyl numbers of RS increased after debranching and acetylation, and the thermal characteristics changed substantially. Debranching led to an increase in onset temperature from 97.79 to 107.64°C; acetylation improved the freeze-thaw stability and swelling power of both the RS and DRS. The blue value of RS varied from 0.424 to 0.640 due to debranching.

In vitro fermentabilities of raw and cooked canna starches and their derivatives

The undigested residues remaining after amylase hydrolysis of raw and cooked canna starches, including native, retrograded, retrograded debranched, heat-moisture treated (HMT), hydroxypropylated and cross-linked starches, were in vitro fermented with pig cecal content. Fermentation of raw native canna starch generated butyric acid as a main short-chain fatty acid (SCFA), while acetic acid was a major component of SCFAs derived from raw modified starches. For cooked starches, the highest butyric acid concentration was found in cross-linked starch (28.8mM), followed by retrograded debranched starch (26.0mM). On the basis of initial weight of starches, retrograded debranched starch was the best substrate since it produced the highest amounts of SCFAs (295.7mmol/100g starch) and butyric acid (86.8mmol/100g starch) after 3 d of fermentation.

Structural characterization of aroid starches by means of chromatographic techniques

Starch functional properties are largely determined by the molecular structure. The weight average molar mass and radius of gyration can be calculated by the analysis of solubilized polymers using AF4-MALLS-DRI systems. The chain length distribution can be determined by analysing debranched starches by gel permeation chromatography (GPC) and high performance anion exchange chromatography (HPAEC-PAD). Aroid starches were used as study case for structure analysis with the abovementioned chromatographic techniques. Amylose and amylopectin chains from aroid starches exhibited weight-average molar mass (Mw) higher than 2.5 × 107 g mol−1 and 5.7 to 13 × 108 g mol−1, respectively. The relatively high values of Mw are correlated to high radius of gyration to both amylose and amylopectin molecules (253–291 nm and 311–410 nm, respectively). The hydrodynamic coefficient (υG) of amylose and amylopectin was 0.6–0.7 and 0.28–0.35, respectively, suggesting random coil conformation for amylose and spherical conformation for amylopectin. The conformation of amylopectin was confirmed by GPC and HPAEC-PAD with the presence of high population of short amylopectin chains (DP 6–12–30% and DP 13–24–50%).

In structure and in-vitro digestibility of waxy corn starch debranched by pullulanase

Waxy corn starch (WCS) debranched by pullulanase was used to prepare starches with different debranching degrees. The effects of debranching degree on in vitro digestibility and structural properties of WCS were investigated. Pullulanase debranching of WCS decreased rapidly digestible starch (RDS), and increased slowly digestible starch (SDS; from 2% to 23%) and resistant starch (RS; from 13% to 19%) contents, with increase in debranching degrees. Weight-average molecular weights of debranched starches (determined using gel permeation chromatography) decreased from 450 kDa to 100 kDa, which were considerably smaller than WCS. X-ray diffraction patterns of debranched and B-type starches were almost similar, confirming that debranched starches contain partially ordered crystalline structures. SDS contents of debranched starches can be increased by increasing debranching degrees and provides useful information for the application of debranched starches in food industries.

Implications of Stisa2 catalytic residue restoration through site directed mutagenesis

Abstract Objective Restoration of catalytic activity of Isa2 from Solanum tuberosum (Stisa2) through restoration of conserved catalytic residues by site directed mutagenesis. Methods The six conserved amino acid residues absent in the Stisa2 gene were restored by mutation using the overlap extension PCR and the asymmetrical overlap extension PCR methods. Next, mutant Stisa2 with restored catalytic residues was expressed in E. coli Rosetta 2 under optimized conditions. Evaluation of debranching activity on starch, amylopectin and β-limit dextrin was carried out by measuring the amount of glucose equivalents released using the bicinchoninic acid assay. Results Both qualitative and quantitative analysis showed that the restoration of the conserved residues in the catalytic site did not restore starch debranching activity. Molecular modeling showed greater than expected distances between the catalytic triad in mutant Stisa2. These additional distances are likely to prevent hydrogen bonding which stabilizes the reaction intermediate, and are critical for catalytic activity. Conclusions These results suggest that during evolution, mutations in other highly conserved regions have caused significant changes to the structure and function of the catalytic network. Catalytically inactive Isa2, which is conserved in starch-producing plants, has evolved important non-catalytic roles such as in substrate binding and in regulating isoamylase activity.

Octenyl succinylation of granular and debranched waxy starches and their application in low-fat salad dressing

The reactions of octenyl succinic anhydride (OSA) at 3% and 15% concentrations (based on weight of starch) with granular and debranched starch forms of waxy rice and waxy potato starches were investigated and compared. Reaction efficiencies of debranched starches with 3% OSA (83.6–87.4%) were significantly higher than those of the granular starches (51.2–56.1%), but their recovery yields were lower (80–85% and 94–98% for debranched and granular starches, respectively). Similar trends were found for the starches modified with 15% OSA but with less reaction efficiencies. Molecular weights of the modified debranched starches were substantially higher than the unmodified ones, presumably due not only to the substituted groups, but also the association of starch chains. Native, debranched, 3% OS granular and 3% OS debranched starches were then evaluated as a fat replacer in a low-fat salad dressing. Viscosities of the dressings incorporated with native and OS granular starches were reduced markedly after storage for 3 d, while the consistency and appearance of the dressings containing debranched starches, either modified or not, were similar to commercial low-fat dressing at up to 90 d storage. Relative calorie values of the dressings containing debranched starches were approximately 50% and 10% less than the reference formula and commercial dressing, respectively.

Structural and functional characterization of RS III produced from gelatinized, enzyme-hydrolyzed and retrograded sweet potato starch

The demand for the application of resistant starch as a functional ingredient is growing, thus, the analysis of its structural, thermal and digestibility properties can help food producers in optimizing industrial applications. The effect of autoclaving (120 °C/30 min)-debranching (2% pullulanase/50 °C) time (1 or 11 or 21 h) and retrogradation temperature (4 or 32 or 60 °C/24 h) on sweet potato starch fractions were studied. Further, the functional, pasting, thermal and structural properties of gelatinized, enzyme-hydrolyzed and retrograded (GEHRS) were also investigated. All the treated starches exhibited a dextrose equivalent value ranging between 3.70 and 5.30%. Debranching of starch at 50 °C for 21 h and retrogradation at 4 °C yielded 63% of RS. Results showed that most of the functional properties had been enhanced in GEHRS. GEHRS registered a lower pasting profile, higher gelatinization temperatures and displayed the B + V diffraction pattern with an increased crystallinity. The SEM of debranched starches showed rough plate-like surfaces with irregularly shaped structures. The study concludes that pullulanase debranching of sweet potato starch at 50 °C for 21 h and subsequent retrogradation at 4 °C produce a higher amount of resistant starch in sweet potato starch.

Effect of pullulanase debranching and storage temperatures on structural characteristics and digestibility of sweet potato starch

The effect of autoclaving (120°C/30min), debranching (2% pullulanase/1h) and storage at 4°C (DS4) or 32°C (DS32) or 60°C (DS60) for 24h on starch fractions, functional, pasting, thermal and structural properties of sweet potato starch was investigated. Results showed that DS4 sample displayed the lower functional properties than other modified starches. Debranching showed a significant increase in the apparent amylose content of native starch from 18.56% to 25%. A higher yield of RS (28.76%) was observed in debranched starch stored at 4°C (DS4) due to the higher degree of retrogradation. All debranched starches showed a substantial decrease in pasting profile and higher gelatinization temperatures than in native starch. B+V X-ray diffraction pattern was observed in debranched starches with increased crystallinity value. The scanning electron micrographs of debranched starches showed rough plate-like surfaces with irregularly shaped structures were observed due to debranching and retrogradation during storage. The study concludes that a combination of autoclaving, debranching and subsequent storage at 4°C is best technique to produce a higher amount of resistant starch in the sweet potato starch.

Comparison of Physicochemical Characteristics of Starch Isolated from Sweet and Grain Sorghum

The worldwide interest about sweet sorghum (Sorghum bicolorL. Moench) goes towards stem sugar, but little has been focused on its grain. The starches were isolated from the grains of eight sweet and four grain sorghum varieties, and their physical, chemical, and morphological properties were carefully compared. The results reflected that starch from sweet varieties usually had larger granule size than that from grain ones, especially from two sweet varieties GL-4 and GL-6 with the granule size of 15.49 μm and 15.67 μm, respectively. The amylose content of sweet varieties starch was lower than that of grain ones. For water solubility index, starch from sweet varieties ranked top, whereas that from grain varieties ranked top for swelling power. The starch from both sweet and grain had A-type crystalline pattern, while the data from13C NMR reflected pattern differences forC1andC6resonance between sweet and grain varieties. Chains length distribution from sweet varieties debranched starch was found a little different from grain one. The starch particles surface of sweet sorghum was smooth with some dents, while that from grain was smooth without appearance of dents. As sweet sorghum has ability to withstand harsh environments where other crops do not and is characterized by low production cost, the extensive potential existed for starch from sweet varieties to be used in starch industries.

Starch Debranching Enzyme Activity and Its Effects on Some Starch Physicochemical Characteristics in Developing Substituted and Complete Triticales (X Triticosecale Wittmack)

The present work was carried out to make a comparison between the starch debranching enzyme activity and the synthesis of total carbohydrates, starch, amylose, and amylopectin in developing kernels of two sets of triticales differing in genome composition (complete and substituted triticales). The results showed that the carbohydrate and starch accumulation observed in both genotypes of triticales increased rapidly at the early stage, reaching the maximum at the medium stage and decreasing slightly or remaining relatively constant at the last stage of kernel development. At the end of the development stage, the mature grains of complete and substituted triticales accumulated 62.5 and 54.6% starch, respectively. Both sets of triticales showed the same amylose accumulation profile as well as degree of polymerization; however, at the maturity stage there was a small but significant difference between the two sets. The final polymerization values of amylose chains in mature seeds of complete and substituted triticales were DP 1,549 and 1,313. A and B1 amylopectin chains of the complete triticales were approximately 19 and 33% shorter than those of the substituted triticales. The complete triticales showed higher isoamylase and pullulanase activities than the substituted triticales, which coincided with the highest starch and amylose contents observed in kernels under development. The results of this study demonstrate that the synthesis of starch differs between the triticale genotypes used in the study, which influences their chemical structure and physicochemical properties.

Structure and digestibility of debranched and repeatedly crystallized waxy rice starch

Debranched waxy rice starch was subjected to repeated crystallization (RC) treatment, and its physicochemical properties and digestion pattern were investigated. The A-type crystalline pattern of native starch was crystallized to a complex of B- and V-type patterns by debranching and RC treatment. Among the treated starches, the relative crystallinity of debranched starch reached its maximum (29.6%) after eight repetitions of crystallization. Changes in weight-average molar mass among treated starch samples were not significantly different. The repeated-crystallized starches showed higher thermal transition temperatures and melting enthalpy than that of debranched starch. As a result, slowly digestible starch (SDS) content of repeated-crystallized starches reached a very high level (57.8%). Results showed that RC treatment induced structural changes of waxy rice starch result in a great amount of SDS.

Amylose and amylopectin branch chain reactivity in a model derivatization system

The impact of starch granule structure on amylose (AM) and amylopectin (AP) chain reactivities was investigated over a 24h period in a model reaction system utilizing a fluorescent probe [DTAF, 5-(4,6-dichlorotriazinyl)aminofluorescein] as a reagent. For various reaction time intervals (0.5, 4, 12, or 24h), molecular reactivities of debranched starch derivatives were assessed via size-exclusion chromatography equipped with refractive index and fluorescence detection. For all starch chain fractions, the initial rate of derivatization (0–0.5h) was rapid, but decreased thereafter. Starch chain reactivities followed the general order: AP long chains≫AM, AP medium chains>AP short chains, though both AM and AP long chain reactivities were somewhat impacted by the high relative reactivity of starch chains eluting in the AM/AP long chain boundary region. Varied starch chain reactivities were attributed to their relative locale within the granule, corroborating the impact of granule architecture on molecular-level reaction patterns of starch chains.

Quality assessment of noodles made from blends of rice flour and canna starch

Canna starch and its derivatives (retrograded, retrograded debranched, and cross-linked) were evaluated for their suitability to be used as prebiotic sources in a rice noodle product. Twenty percent of the rice flour was replaced with these tested starches, and the noodles obtained were analyzed for morphology, cooking qualities, textural properties, and capability of producing short-chain fatty acids (SCFAs). Cross-linked canna starch could increase tensile strength and elongation of rice noodles. Total dietary fiber (TDF) content of noodles made from rice flour was 3.0% and increased to 5.1% and 7.3% when rice flour was replaced with retrograded and retrograded debranched starches, respectively. Cooking qualities and textural properties of noodles containing 20% retrograded debranched starch were mostly comparable, while the capability of producing SCFAs and butyric acid was superior to the control rice noodles; the cooked noodle strips also showed fewer tendencies to stick together.

Oligosaccharide and Substrate Binding in the Starch Debranching Enzyme Barley Limit Dextrinase

Complete hydrolytic degradation of starch requires hydrolysis of both the α-1,4- and α-1,6-glucosidic bonds in amylopectin. Limit dextrinase (LD) is the only endogenous barley enzyme capable of hydrolyzing the α-1,6-glucosidic bond during seed germination, and impaired LD activity inevitably reduces the maltose and glucose yields from starch degradation. Crystal structures of barley LD and active-site mutants with natural substrates, products and substrate analogues were sought to better understand the facets of LD–substrate interactions that confine high activity of LD to branched maltooligosaccharides. For the first time, an intact α-1,6-glucosidically linked substrate spanning the active site of a LD or pullulanase has been trapped and characterized by crystallography. The crystal structure reveals both the branch and main-chain binding sites and is used to suggest a mechanism for nucleophilicity enhancement in the active site. The substrate, product and analogue complexes were further used to outline substrate binding subsites and substrate binding restraints and to suggest a mechanism for avoidance of dual α-1,6- and α-1,4-hydrolytic activity likely to be a biological necessity during starch synthesis.

Preparation and characterization of pullulanase debranched starches and their properties for drug controlled-release

Linear short amylose and glucan tend to align and aggregate to form hydrogels that hold less water. The drug release properties of debranched starch based tablets can be controlled by the pullulanase modification conditions.

Pullulanase hydrolysis behaviors and hydrogel properties of debranched starches from different sources

In the present study, debranched starches (DBS) from different sources were prepared by treatment with pullulanase with an aim to investigate the differences in pullulanase hydrolysis and the hydrogel properties of the resulting DBS. The results indicated that all DBS were V-type starches with hollow, single-helical structures. Debranched maize starch (DBMS) and wheat starch (DBWS) performed similarly. Pullulanase treatment resulted in an obvious reduction in viscosity for all tested starches except debranched pea starch (DBPeS). The average molecular weight of small fragments of debranched potato starch (DBPoS) was higher than that of the other samples, and longer lateral chains tended to be cleaved by pullulanase for DBPoS. The results of the solubility and water-holding capacity analyses indicated the DBS starches were capable of capturing water to form hydrogels. DBPoS was more easily digested by gastrointestinal amylase, whereas its pea-source counterpart showed the opposite trend. The results confirmed that generation of short linear glucan chains by pullulanase hydrolysis effectively improved solubility and water-holding capacity, which contributed to their hydrogel-forming properties.

Physicochemical and structural properties of debranched waxy rice, waxy corn and waxy potato starches

Starch gels of waxy rice (WR), waxy corn (WC) and waxy potato (WP) were hydrolyzed with pullulanase, and the products obtained were analyzed for unit chain length distribution and certain physicochemical properties. Average chain lengths of debranched WR, WC and WP starches were 18.2, 19.2 and 25.6, respectively. The debranched starches had a greater ability to form complexes with iodine and possessed higher solubility but lower viscosity compared with their corresponding dispersed native starches. Their complexing abilities with fatty acids (palmitic and butyric acids) were found to be dependent on the unit chain length. Among the three debranched starches, debranched waxy potato starch exhibited the greatest ability to form complexes with iodine and fatty acids, while debranched waxy rice starch had the highest solubility and lowest viscosity. The debranched starches formed stable gels at high concentrations (10–20%) and formed precipitates at concentrations up to 5%.

RETRACTED: Preparation and characterization of hydrophilic debranched starch modified by pullulanase on swollen granule starch

RETRACTED: Preparation and characterization of hydrophilic debranched starch modified by pullulanase on swollen granule starch

Exploring extraction/dissolution procedures for analysis of starch chain-length distributions

The analysis of starch chain-length distributions (CLDs) is important for understanding starch biosythesis–structure–property relations. It is obtained by analyzing the number distribution of the linear glucan chains released by enzymatic debranching of starch α-(1→6) glycosidic bonds for subsequent characterization by techniques such as fluorophore-assisted carbohydrate electrophoresis (FACE) or size-exclusion chromatography (SEC). Current literature pretreatments for debranching prior to CLD determination involve varying protocols, which might yield artifactual results. This paper examines the two widely used starch dissolution treatments with dimethyl sulfoxide (DMSO) containing 0.5% (w/w) lithium bromide (DMSO-LiBr) at 80°C and with aqueous alkaline (i.e. NaOH) solvents at 100 ˚C. Analyses by FACE with a very high range of degree of polymerization, and by SEC, of the CLD of barley starches with different structures show the following. (1) The NaOH treatment, even at a dilute concentration, causes significant degradation at higher degrees of polymerization, leading to quantitatively incorrect CLD results in longer amylopectin and in amylose chains. (2) Certain features in both amylopectin and amylose fractions of the CLD reduced to bumps or are missing with NaOH treatment. (3) Overestimation of amylose chains in starch CLD due to incomplete amylopectin dissolution with dilute NaOH concentration. These results indicate starch dissolution with DMSO-LiBr is the method of choice for minimizing artifacts. An improved pretreatment protocol is presented for starch CLD analysis by FACE and SEC.