Dynamic and extensional properties of starch in aqueous dimethylsulfoxide

The effect of starch composition and concentration on the rheological properties of starch in a mixed solvent, water–DMSO, was investigated in dynamic shear and extensional mode. High amylose corn starch containing 70% amylose and 30% amylopectin, common corn starch containing 25% amylose and 75% amylopectin, and waxy corn starch containing about 99% amylopectin were used in this study. Concentrations of 2, 4, 6, and 8% (w/v) in 10% water-90% DMSO (v/v) were used for each starch type. An increase in the amylopectin content of starch from 30 to 99% caused a change in behavior from semidilute solution to viscoelastic solid at a concentration of 8% (w/v). At a concentration of 2%, an increase in the amylopectin content of starch from 30 to 99% caused a change from Newtonian to incipient gel-like behavior. Behavior at intermediate concentrations of 4 and 6% (w/v) varied from semidilute to critical gel-like with increasing amylopectin content. A power-law relaxation was observed for all concentrations of common and waxy corn starches with the slope decreasing with increase in concentrations. A 2% waxy corn starch solution displayed extension thinning behavior, while a 2% high amylose corn starch solution displayed Newtonian behavior.     

Locations of hypochlorite oxidation in corn starches varying in amylose content

The general oxidation mechanism by hypochlorite on starch has been well studied, but the information on the distribution of the oxidation sites within starch granules is limited. This study investigated the locations where the oxidation occurred within corn starch granules varying in amylose content, including waxy corn starch (WC), common corn starch (CC), and 50% and 70% high-amylose corn starch (AMC). Oxidized corn starches were surface gelatinized by 13 M LiCl at room temperature to different extents (approximately 10%, 20%, 30%, and 40%). The surface-gelatinized remaining granules were separated and studied for structural characteristics including carboxyl content, amylose content, amylopectin chain-length distribution, thermal properties, and swelling properties. Oxidation occurred mostly at the amorphous lamellae. More carboxyl groups were found at the periphery than at the core of starch granules, which was more pronounced in oxidized 70% AMC. More amylose depolymerization from oxidation occurred at the periphery of CC. For WC and CC, amylopectin long chains (>DP 36) were more prone to depolymerization by oxidation. The gelatinization properties as measured by differential scanning calorimetry also supported the changes in amylopectin fine structure from oxidation. Oxidized starches swelled to a greater extent than their unmodified counterparts at all levels of surface removal. This study demonstrates that the locations of oxidation and physicochemical properties of oxidized starches are affected by the molecular arrangement within starch granules.     

Sorption of Monoterpenoids and Sesquiterpenoids by Natural Polysaccharides

Sorption of terpenoids (essential oil components) from aqueous solutions by six types of native food starches was studied by capillary gas chromatography. Sorption of volatile substances did not depend on amylose content in starch and specific surface of its granules. The degree of sorption was maximum (86%) for corn starch containing 25–28% amylose and decreased in the following order: tapioca starch (77%) > potato starch (74%) > wheat starch (70%) > high-amylose corn starch (58%) > amylopectin corn starch (57%). Amylopectin corn starch differed from other starches in the mechanism of sorption and selectivity to compounds with various functional groups.     

Effects of different starch sources on Bacillus spp. in intestinal tract and expression of intestinal development related genes of weanling piglets

The study was conducted to evaluate the effects of different starch sources on Bacillus spp. in intestinal tract and expression of intestinal development related genes of weanling piglets. Twenty-eight PIC male piglets were divided into four homogeneous groups according to initial body weight (similar birth and parity, weaned at 21 ± 1.5 days). Diets for the four treatments consisted of corn starch, wheat starch, tapioca starch and pea starch with the determined ratio for amylose to amylopectin of 0.21, 0.24, 0.12 and 0.52 respectively. Real-time quantitative polymerase chain reaction was applied to: (1) detect genomic DNA of Bacillus and to quantify the number of Bacillus in the intestinal tract chyme of piglets with the primers and probe which designed based on the 16S rRNA sequences of maximum species of Bacillus on GenBank; (2) measure the mRNA level of glucagon-like peptide 2 (GLP-2), insulin-like growth factors 1 (IGF-1) and epidermal growth factor (EGF) in duodenum, jejunum and ileum. Results showed that the number of Baciilus and the percentage based on all bacteria in the whole intestinal content of piglets fed pea starch was highest in all groups (P < 0.05). There was no significant differance on copy numbers for all bacteria and Bacillus in the whole intestinal tract of piglets between the corn starch group and wheat starch group (P > 0.05). In addition, the expression level of GLP-2, IGF-1 mRNA in jejunum and ileum of pea starch treatment (the high amylose/amylopectin ratio) were increased while the tapioca starch decreased their mRNA level significantly compared to other three treatments (P < 0.05). There was no significant difference for the mRNA level of EGF in each group. The present study revealed that high amylose/amylopectin ratio of starches significantly enhanced the numbers of Bacillus in all segments of intestine and the mRNA level of intestinal development related genes.     

Lipids-free waxy corn starch as a substrate for distillery yeasts <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Utilization of lipids-free waxy starch by distillery yeasts in fuel ethanol production can contribute to better management of renewable resources, like cereals, especially maize Zea mays L. But the efficient conversion of starch into glucose-rich fermentable substrate, and subsequently to ethanol, needs more research on hydrolysis and fermentation conditions. The aim of this study was to evaluate the lack of natural corn grain lipids on the process of simultaneous saccharification and fermentation using chemometric techniques of designed experiments, commercial enzymatic preparations and distillery yeasts Saccharomyces cerevisiae CCY-11-3. Based on the results and statistical software support we can conclude that extraction of lipids from corn grains did not lead to statistically significant increase or decrease of glucose concentration in starch hydrolysis. The ethanol concentration in fermentation mash according to analysis was not statistically significantly affected by lipids extraction. The separated lipids could serve as a source of very valuable corn oil.     

Two Forms of Glucoamylase from Mucor rouxianus

Both of the two forms of glucoamylase (glucoamylases I and II) from the wheat bran culture of Mucor rouxianus hydrolyzed amylopectin, amylose, glycogen, soluble starch, maltotriose, and maltose, but did not act on isomaltose and isomaltotriose. Phenyl α-maltoside was hydrolyzed into glucose and phenyl α-glucoside by both glucoamylases. Maltose was hydrolyzed about one-fifth as rapidly as amylopectin. Both enzymes produced glucose from amylopectin, amylose, glycogen, soluble starch in the yields of almost complete hydrolysis. They hydrolyzed amylose with the inversion of configuration, producing the β-anomer of glucose. Glucoamylase II hydrolyzed raw starch at 3-fold higher rate than glucoamylase I. The former hydrolyzed rice starch almost completely into glucose, whereas the latter hydrolyzed it incompletely (nearly 50%).     

Real‐time monitoring of high‐gravity corn mash fermentation using in situ raman spectroscopy

In situ Raman spectroscopy was employed for real‐time monitoring of simultaneous saccharification and fermentation (SSF) of corn mash by an industrial strain of Saccharomyces cerevisiae. An accurate univariate calibration model for ethanol was developed based on the very strong 883 cm^?1 C–C stretching band. Multivariate partial least squares (PLS) calibration models for total starch, dextrins, maltotriose, maltose, glucose, and ethanol were developed using data from eight batch fermentations and validated using predictions for a separate batch. The starch, ethanol, and dextrins models showed significant prediction improvement when the calibration data were divided into separate high‐ and low‐concentration sets. Collinearity between the ethanol and starch models was avoided by excluding regions containing strong ethanol peaks from the starch model and, conversely, excluding regions containing strong saccharide peaks from the ethanol model. The two‐set calibration models for starch (R² = 0.998, percent error = 2.5%) and ethanol (R² = 0.999, percent error = 2.1%) provide more accurate predictions than any previously published spectroscopic models. Glucose, maltose, and maltotriose are modeled to accuracy comparable to previous work on less complex fermentation processes. Our results demonstrate that Raman spectroscopy is capable of real time in situ monitoring of a complex industrial biomass fermentation. To our knowledge, this is the first PLS‐based chemometric modeling of corn mash fermentation under typical industrial conditions, and the first Raman‐based monitoring of a fermentation process with glucose, oligosaccharides and polysaccharides present. Biotechnol. Bioeng. 2013; 110: 1654–1662. © 2013 Wiley Periodicals, Inc.     

Scanning Electron Microscopy and Fermentation Studies on Selected Known Maize Starch Mutants Using STARGEN? Enzyme Blends

The conversion of maize (corn) kernels to bio-ethanol is an energy-intensive process involving many stages. One step typically required is the liquefaction of the ground kernel to enable enzyme hydrolysation of the starch to glucose. The enzyme blends STARGEN? (Genencor) are capable of hydrolysing starch granules without liquefaction, reducing energy inputs and increasing efficiency. Studies were conducted on maize starch mutants amylose extender 1 (ae1), dull 1 (du1) and waxy 1 (wx1) in the inbred line Oh43 to determine whether different maize starches affected hydrolysation rates by STARGEN? 001 and STARGEN? 002. All mutants contained similar proportions of starch in the kernel but varied in the amylose to amylopectin ratio. Ground maize kernels were incubated with STARGEN? 001 and viewed using scanning electron microscopy to examine the hydrolysis action of STARGEN? 001 on the starch granules. The ae1 mutant exhibited noticeably less enzymic hydrolysis action, on the granules visualised, than wx1 and background line Oh43. Kernels were batch-fermented with STARGEN? 001 and STARGEN? 002. The ae1 mutant exhibited a 50% lower ethanol yield compared to the wx1 mutant and background line. A final study compared hydrolysation rates of STARGEN? 001 and STARGEN? 002 on purified maize starch, amylopectin and amylose. Though almost twice the amylopectin was hydrolysed using STARGEN? 002 than STARGEN? 001 in this trial, fermentations using STARGEN? 002 resulted in lower ethanol yields than fermentations using STARGEN? 001. Both STARGEN? enzyme blends were more suitable for the fermentation of high amylopectin maize starches than high amylose starches.     

不同类型玉米籽粒的营养品质及其与籽粒质地的关系

测定普通玉米、爆裂玉米、糯玉米和甜玉米4种类型玉米籽粒不同发育时期的直链淀粉、支链淀粉、总淀粉、可溶性糖和蛋白的含量,分析这些营养物质与角质率的关系。结果表明：灌浆期间4种类型玉米的直链淀粉、支链淀粉和总淀粉含量呈上升趋势,总蛋白含量呈下降趋势,可溶性糖含量变化规律不明显。爆裂玉米的直链淀粉含量始终最高（4．7％-23．1％）,甜玉米（1．4％-4．6％）和糯玉米（2．3％-4．9％）的始终较低;甜玉米的支链淀粉含量一直最低（15．7％-35．5％）,除授粉10d以外,糯玉米的支链淀粉含量一直最高（65．5％-69．8％）;甜玉米总淀粉含量始终最低（17．1％36.1％）、总蛋白含量（15．2％-26．9％）和授粉30d后的可溶性糖含量最高（14．2％-17．6％）。高蛋白含量可能是爆裂玉米和甜玉米角质率高的原因,糯玉米的角质率低可能与支链淀粉含量高和蛋白积累少有关。     

Sorption of mono- and sesquiterpenes by natural polysaccharides

Sorption of terpenoids (essential oil components) from aqueous solutions by six types of native food starches was studied by capillary gas chromatography. Sorption of volatile substances did not depend on amylose content in starch and specific surface of its granules. The degree of sorption was maximum (86%) for corn starch containing 25-28% amylose and decreased in the following order: tapioca starch (77%) > potato starch (74%) > wheat starch (70%) > high-amylose corn starch (58%) > amylopectin corn starch (57%). Amylopectin corn starch differed from other starches in the mechanism of sorption and selectivity to compounds with various functional groups.     

Charakterisierung der Stärkehydrolysate nach Einwirkung einer thermostabilen α-Amylase

The action of thermostable α-amylase produced by Bacillus licheniformis 44MB82 strain on soluble and insoluble starch, amylose and amylopectin at temperatures 30°C and 90°C was studied. The hydrolysis of soluble starch proceeded rapidly for 10 to 15 minutes after which the maltodextrins thus formed were further dissociated. In the course of 60-minutes enzyme treatment mainly glucose, maltose and maltosugars (from G₃ to G₆) as low molecular weight products were found and the formation of maltcse and maltotriose was increased by the longer treatment. The hydrolysis of insoluble starch and amylopectin proceeded in the same way while the amylose was hydrolysed slowly.     

In Vitro Utilization of Amylopectin and High-Amylose Maize (Amylomaize) Starch Granules by Human Colonic Bacteria

It has been well established that a certain amount of ingested starch can escape digestion in the human small intestine and consequently enters the large intestine, where it may serve as a carbon source for bacterial fermentation. Thirty-eight types of human colonic bacteria were screened for their capacity to utilize soluble starch, gelatinized amylopectin maize starch, and high-amylose maize starch granules by measuring the clear zones on starch agar plates. The six cultures which produced clear zones on amylopectin maize starch- containing plates were selected for further studies for utilization of amylopectin maize starch and high-amylose maize starch granules A (amylose; Sigma) and B (Culture Pro 958N). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect bacterial starch-degrading enzymes. It was demonstrated that Bifidobacterium spp., Bacteroides spp., Fusobacterium spp., and strains of Eubacterium, Clostridium, Streptococcus, and Propionibacterium could hydrolyze the gelatinized amylopectin maize starch, while only Bifidobacterium spp. and Clostridium butyricum could efficiently utilize high-amylose maize starch granules. In fact, C. butyricum and Bifidobacterium spp. had higher specific growth rates in the autoclaved medium containing high-amylose maize starch granules and hydrolyzed 80 and 40% of the amylose, respectively. Starch-degrading enzymes were cell bound on Bifidobacterium and Bacteroides cells and were extracellular for C. butyricum. Active staining for starch-degrading enzymes on SDS-PAGE gels showed that the Bifidobacterium cells produced several starch-degrading enzymes with high relative molecular (M_r) weights (>160,000), medium-sized relative molecular weights (>66,000), and low relative molecular weights (<66,000). It was concluded that Bifidobacterium spp. and C. butyricum degraded and utilized granules of amylomaize starch.     

Effect of high hydrostatic pressure on the formation of radicals in maize starches with different amylose content

Native and high pressure-treated (water suspensions, 650 MPa) waxy maize starch, containing mainly amylopectin, and Hylon VII, rich in amylose, were studied for their ability to generate free radicals upon thermal treatment at 180–230 °C. The electron paramagnetic resonance (EPR) spectroscopy was used to characterize the nature, number and stability of radicals. Various stable and short living (stabilized by N-tert-butyl-α-phenylnitrone (PBN) spin trap) radical species were formed. It was found, that at given conditions the waxy maize starch reveals higher ability to generate radicals, than Hylon VII. The presence of water and high pressure pretreatment of starches, both resulted in the reduction of the amount of thermally generated radicals. The decrease in crystallinity of waxy maize starch and of Hylon VII, occurring upon high pressure treatment, leads to the increase of the relative amount of fast rotating component in the EPR spectrum of both types of starches.     

The influence of amylose and amylopectin characteristics on gelatinization and retrogradation properties of different starches

Physico-chemical properties of starch from wheat, rye, barley (waxy, high-amylose and normal-amylose), waxy maize, pea and potato (normal-amylose and high-amylopectin) were studied. Emphasis was given to the amylose (total, apparent and lipid-complexed) and amylopectin characteristics as well as to the gelatinization and retrogradation properties measured using differential scanning calorimetry. The total amylose content varied from ca. 1 % for waxy maize to 37% for high-amylose barley. The amylopectin characteristics were determined by high-performance size-exclusion chromatography after debranching with isoamylase. The weight-average degree of polymerization ( _w) was 26, 33 and 27 for the A-, B-, and C-type starches, respectively. In general, the potato starches exhibited the highest retrogradation enthalpies and the cereal starches the lowest, while the pea starch showed an intermediate retrogradation enthalpy. The data were analysed by principal component analysis (PCA). The _w showed positive correlation to the melting interval, the peak minimum, the offset temperatures of the retrogradation-related endotherm as well as to the gelatinization and retrogradation enthalpies. However, the high-amylose barley retrograded to a greater extent than the other cereal starches, despite low _w (24). The amylose content was negatively correlated to the onset and the peak minimum temperatures of gelatinization.     

The elongation of amylose and amylopectin chains in isolated starch granules

The aim of this work was to investigate the conditions required for amylose synthesis in starch granules. Although the major granule-bound isoform of starch synthase - GBSSI - catalyses the synthesis of amylose in vivo, ¹⁴C from ADP[¹⁴C]glucose was incorporated primarily into a specific subset of amylopectin chains when supplied to starch granules isolated from pea (Pisum sativum L.) embryos and potato (Solanum tuberosum L.) tubers. Incubation of granules with soluble extracts of these organs revealed that the extracts contained compounds that increased the incorporation of ¹⁴C into amylose. These compounds were rendered inactive by treatment of the extracts with α-glucosidase, suggesting that they were malto-oligosaccharides. Consistent with this idea, provision of pure malto-oligosaccharides to isolated granules resulted in a dramatic shift in the pattern of incorporation of ¹⁴C, from amylopectin chains to amylose molecules. Comparison of the pattern of incorporation in granules from wild-type peas and lam mutant peas which lack GBSSI showed that this effect of malto-oligosaccharides was specifically on GBSSI. The significance of these results for understanding of the synthesis of amylose and amylopectin in storage organs is discussed.     

Structural characteristics and physicochemical properties of oxidized corn starches varying in amylose content

The effects of amylose content on the extent of oxidation and the distribution of carboxyl groups in hypochlorite-oxidized corn starches were investigated. Corn starches including waxy corn starch (WC), common corn starch (CC), and 50% and 70% high-amylose corn starches (AMC) were oxidized with NaOCl at three concentrations (0.8%, 2%, and 5%). Carboxyl and carbonyl content of oxidized starches increased with increasing NaOCl concentration. High-AMC (70%) had slightly higher carboxyl and carbonyl contents at 0.8% NaOCl, whereas WC had significantly higher carboxyl and carbonyl contents at 2% and 5% NaOCl levels. Carbohydrate profiles by high-performance size-exclusion chromatography indicate that amylose was more susceptible to depolymerization than amylopectin. Degradation of amylopectin long chains (DP >24) was more pronounced in WC and CC than in AMCs. The crystalline lamellae of WC started to degrade at 2% NaOCl, but those of the other corn starches remained intact even at 5% NaOCl level according to X-ray crystallinity. By using anion-exchange chromatography for separation and size-exclusion chromatography for characterization, carboxyl groups were found to be more concentrated on amylopectin than on amylose, particularly in AMCs. Oxidation decreased gelatinization temperature and enthalpy with WC showing the most decrease and 70% AMC showing the least. The gelatinization enthalpy of 50% AMC decreased significantly faster than those of CC and 70% AMC after 0.8% oxidation. Retrogradation of amylopectin slightly increased after oxidation with increasing oxidation level. The peak viscosities of oxidized WC and CC were higher than those of their native counterparts at 0.8% NaOCl, but this increase was not observed in AMCs. The setback viscosities of 2% NaOCl-oxidized 50% and 70% AMCs were much higher than those of the unmodified counterparts. The extent of oxidation and physicochemical properties of oxidized starches varied greatly with the amylase:amylopectin ratio of corn starches. Amylose was suggested to play an important role in controlling the oxidation efficiency.     

Alkaliviscogram and Other Properties of Starch of Tropical Rice

In the alkaliviscogram of starch of 26 nonwaxy rices grown in the tropics, gelatinization normality correlated positively with final gelatinization temperature (BEPT) of starch (r=0.969^**) and negatively with alkali spreading value of milled rice (r= ?0.931^**). Peak viscosity was not linearly related to amylose content. Among samples of rice starch having a high amylose (>28%) content, peak viscosity was correlated with the gel consistency of starch (r=?0.690^**) and of milled rice (r=?0.644^**) (n = 18). These high-amylose starches showed the widest variation in peak viscosity. Amylose content, and gel consistency were inherited from the same parent in all nine varieties and lines studied, whereas peak viscosity, gelatinization normality and the final BEPT were inherited from either parent. The starch of five waxy rices showed higher peak viscosities even at a concentration of 1.8% as compared with a 2.0% nonwaxy rice starch.     

Internal structure and physicochemical properties of corn starches as revealed by chemical surface gelatinization

The organization of amylose and amylopectin within starch granules is still not well elucidated. This study investigates the radial distribution of amylose and amylopectin in different corn starches varying in amylose content (waxy corn starch (WC), common corn starch (CC), and 50% and 70% amylose corn starches (AMC)). Corn starches were surface gelatinized by 13 M LiCl at room temperature to different extents (approximately 10%, 20%, 30%, and 40%). The gelatinized surface starch and remaining granules were characterized for amylose content, amylopectin chain-length distribution, thermal properties, swelling power (SP), and water solubility index (WSI). Except for the outmost 10% layer, the amylose content in CC increased slightly with increasing surface removal. In contrast, amylose was more concentrated at the periphery than at the core for 50% and 70% AMC. The proportion of amylopectin A chains generally decreased while that of B1 chains generally increased with increasing surface removal for all corn starches. The gelatinization enthalpy usually decreased, except for 70% AMC, whereas the retrogradation enthalpy relatively remained unchanged for CC but increased for WC, 50% and 70% AMC with increasing surface removal. The SP and WSI increased with increasing surface removal for all corn starches, with WC showing a significant increase in SP after the removal of the outmost 10% layer. The results of this study indicated that there were similarities and differences in the distribution of amylose and amylopectin chains along the radial location of corn starch granules with varying amylose contents. More amylose-lipid complex and amylopectin long chains were present at the periphery than at the core for amylose-containing corn starches.     

Bacillus stearothermophilus Neopullulanase Selective Hydrolysis of Amylose to Maltose in the Presence of Amylopectin

The specificity of Bacillus stearothermophilus TRS40 neopullulanase toward amylose and amylopectin was analyzed. Although this neopullulanase completely hydrolyzed amylose to produce maltose as the main product, it scarcely hydrolyzed amylopectin. The molecular mass of amylopectin was decreased by only one order of magnitude, from approximately 10⁸ to 10⁷ Da. Furthermore, this neopullulanase selectively hydrolyzed amylose when starch was used as a substrate. This phenomenon, efficient hydrolysis of amylose but not amylopectin, was also observed with cyclomaltodextrinase from alkaliphilic Bacillus sp. strain A2-5a and maltogenic amylase from Bacillus licheniformis ATCC 27811. These three enzymes hydrolyzed cyclomaltodextrins and amylose much faster than pullulan. Other amylolytic enzymes, such as bacterial saccharifying α-amylase, bacterial liquefying α-amylase, β-amylase, and neopullulanase from Bacillus megaterium, did not exhibit this distinct substrate specificity at all, i.e., the preference of amylose to amylopectin.     

In vitro utilization of amylopectin and high-amylose maize (Amylomaize) starch granules by human colonic bacteria.

It has been well established that a certain amount of ingested starch can escape digestion in the human small intestine and consequently enters the large intestine, where it may serve as a carbon source for bacterial fermentation. Thirty-eight types of human colonic bacteria were screened for their capacity to utilize soluble starch, gelatinized amylopectin maize starch, and high-amylose maize starch granules by measuring the clear zones on starch agar plates. The six cultures which produced clear zones on amylopectin maize starch- containing plates were selected for further studies for utilization of amylopectin maize starch and high-amylose maize starch granules A (amylose; Sigma) and B (Culture Pro 958N). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect bacterial starch-degrading enzymes. It was demonstrated that Bifidobacterium spp., Bacteroides spp., Fusobacterium spp., and strains of Eubacterium, Clostridium, Streptococcus, and Propionibacterium could hydrolyze the gelatinized amylopectin maize starch, while only Bifidobacterium spp. and Clostridium butyricum could efficiently utilize high-amylose maize starch granules. In fact, C. butyricum and Bifidobacterium spp. had higher specific growth rates in the autoclaved medium containing high-amylose maize starch granules and hydrolyzed 80 and 40% of the amylose, respectively. Starch-degrading enzymes were cell bound on Bifidobacterium and Bacteroides cells and were extracellular for C. butyricum. Active staining for starch-degrading enzymes on SDS-PAGE gels showed that the Bifidobacterium cells produced several starch-degrading enzymes with high relative molecular (M(r)) weights (>160,000), medium-sized relative molecular weights (>66,000), and low relative molecular weights (<66,000). It was concluded that Bifidobacterium spp. and C. butyricum degraded and utilized granules of amylomaize starch.