Normal Maize Starch Research Articles

A study on the thermal stability of amylose-amylopectin and amylopectin-amylopectin in cross-linked starches through iodine binding capacity

It has been proved that when normal maize starch granules were cross-linked, amylose did not cross-link to one another, but amylose-amylopectin (A-AP) and amylopectin-amylopectin (AP-AP) were carried out. The objective of this study was to study the thermal stability of the cross-linked starches (CLs), and correlate it to iodine binding capacity (IBC) of native starch and CLs with different water bath temperatures (20, 40, 60, 80, 100° C, the starch slurry was prepared at a temperature of 20° C). CLs was prepared through cross-linking of normal maize starch with 0.1, 1, and 10% sodium trimetaphosphate (STMP) and 0.1% phosphorous oxychloride (POCl3). At different temperatures, no differences were observed for the IBC of native starch, however, the IBC of CLs decreased with the increase of the water bath temperature. At boiling temperature, the IBC of all the cross-linked starches was similar to the native maize, indicating that nearly all the amylose was leached out and had formed blue complexes with iodine. In addition, at 20° C, the IBC of the cross-linked starch was negatively related to the cross-linking agent level added.

A simple and green method for preparation of non-crystalline granular starch through controlled gelatinization

Non-crystalline granular starch (NCGS) is of considerable interest because of its unique functional properties. In this study, controlled gelatinization combined with sedimentation was used to prepare the NCGS from normal maize starch. The morphology and crystalline state of the NCGS were investigated using optical and electron microscopy, calorimetry, and X-ray diffraction (XRD). These methods showed that starch granules maintained a granule structure up to around 80 °C but they completely dissociated at higher temperatures. The number of the granules that disappeared the birefringence gradually increased with the temperature increase, and completely disappeared at 75 °C. The DSC results indicated that the crystalline structure of amylopectin was totally destroyed when the treating temperature was greater than or equal to 75 °C. The XRD patterns showed that the crystalline structure of native starch was thoroughly disappeared at 75 °C. However, B-type and V-type crystals formed in the samples heated at 80 °C or higher, corresponding to the short-term retrogradation of amylose and the formation of amylose-lipids complexes, respectively.

Effects of weak-light stress during grain filling on the physicochemical properties of normal maize starch

The grain development of normal maize in Southern China is affected by decreases in sunlight intensity over the period of mid-June to mid-July. This study examined the starch structure and function of four normal maize varieties that had been exposed to weak-light stress (50% light deprivation; ambient light conditions served as the control) during grain filling. In all tested varieties, light deprivation decreased the contents of starch and amylose, and increased the size of starch granules and the proportion of long chains in amylopectin. Shading increased the relative crystallinity and ordered-to-amorphous ratio of starch. Shading decreased the gelatinization and retrogradation enthalpies and pasting and gelatinization temperatures of starches but increased retrogradation percentage and pasting viscosities. In conclusion, weak-light stress during grain filling increases starch viscosity and retrogradation tendency and decreases thermal stability by reducing amylose content, increasing the sizes of starch granules and the proportion of long chains in amylopectin, and improving the relative crystallinity.

High‐Solids Bio‐Conversion of Maize Starch to Sugars and Ethanol

In current industrial production, maize is the predominant crop used to produce starch which is converted to sugars. In this study, liquefaction and fermentation of normal maize starch at different solid contents are examined. Starch is liquefied at solid contents from 20 to 60% by thermostable α‐amylase at 90 °C. The molecular weight distributions of the dextrins from starch liquefaction, determined by gel‐permeation chromatography, are practically the same for those generated at 20–40% solids, whereas those at 50–60% solids contain increased levels of high molecular weight dextrins. A higher solids level (40–60%) requires more α‐amylase to produce liquefied starch with a reducing sugar content of 9–15%. The starch hydrolysates are subjected to a simultaneous saccharification and fermentation (SSF) process that is conducted at 20–60% solids, 30 °C for up to 72 h. The highest ethanol concentration (17.4%, v/v) is obtained after 72 h from the 30% starch hydrolysate with reducing sugar content of 12–14%. Enzymatic liquefaction of normal maize starch at high solids content (40–60%) is feasible and the high solids enzyme conversion of starch could find potential applications in productions of sugars and chemicals made by fermentation of sugars.

Inclusion Complexes of Non‐Granular Maize Starch with Fatty Acids and Ibuprofen. A Comparative Study of Their Morphology and Structure

Drum dried pregelatinized normal maize starch complexes with fatty acids (decanoic, myristic, palmitic, stearic, and oleic acid) and ibuprofen are studied by various techniques. The aim of the study is to investigate the structural and morphological characteristics of the starch complexes and assess whether any differences might exist between the starch‐fatty acid systems and the starch‐ibuprofen system. The complexes are prepared at 30, 50, or 70 °C. X‐ray diffraction analysis reveals the semicrystalline V‐type structure of all complexes regardless the temperature of their preparation. The degree of crystallinity (%) of complexes increases with the increase in the preparation temperature while the size of crystals decreases. The crystal size of ibuprofen complexes is smaller than that of the fatty acid ones. DSC thermal analysis shows that the dissociation temperature of the complexes ranged from 95 to 125 °C. The enthalpy of dissociation of ibuprofen complexes is much lower than that of the fatty acid ones. SEM microscopy reveales the formation of spherulites or lamellae in the matrix of the complexes. FTIR spectroscopy and light microscopy confirmed the formation of starch complexes with fatty acids and ibuprofen.

Assembly of Pickering emulsions using milled starch particles with different amylose/amylopectin ratios

Three maize starches (normal maize starch, high-amylose maize starch and waxy maize starch) with different amylose/amylopectin ratios were modified through a media milling process to form nano/submicrometer milled starch particles. The physiochemical properties of these starch particles during milling process, including particle size, morphology, crystallinity and gelatinization properties were studied. The effects of starch chemical structure and milling time on the properties of milled starch particles-stabilized Pickering emulsions were also investigated. Pickering emulsions stabilized by milled starch particles with different amylose/amylopectin ratios exhibited significant difference in terms of stabilization capability and rheological properties. Milled high-amylose maize starch particles have the best stabilization ability, followed by milled normal maize starch particles. Furthermore, the stabilization capacity of the milled starch particles improves with the increase of milling time. This research suggests that stable food-grade Pickering emulsions can be formulated by choosing maize starch of proper amylose/amylopectin ratios.

Effect of heat-moisture treatment on the physicochemical properties and in vitro digestibility of the starch-guar complex of maize starch with varying amylose content

Waxy maize starch (W), normal maize starch (N), and Hylon V (H) were modified by heat-moisture treatment (HMT) with guar gum (G). The physicochemical properties of the HMT starch-guar samples (modified samples: HMT-WG, HMT-NG, and HMT-HG) were investigated and compared with those of starch-guar mixtures (WG, NG, and HG). Then, the swelling power, solubility, granule morphology, thermal properties, in vitro digestibility and isothermal hygroscopic curves of the samples were evaluated. The relative crystallinity of the samples decreased after HMT. HMT-HG tended to form more stable crystals. HG was B + V type, which means that the high amylose starch content results in the formation of a complex with guar gum. In addition, the digestibility of the samples decreased with the decreasing amylose content. HMT-HG showed the highest resistance. Furthermore, HMT decreased the hygroscopicity significantly, decreased the gelatinization enthalpy of the samples in the order of WG > NG > HG and helped slow down the long-term ageing of N/WG. Additionally, HMT-NG was the most resistant to moisture at a lower humidity (45%) and had the lowest gelatinization temperature.

Influence of Fluidized Bed Jet Milling on Structural and Functional Properties of Normal Maize Starch

Normal maize starch samples with moisture contents of 11.24%, 6.18%, and 1.5% are ground using a fluidized bed jet mill at classifier frequencies of 2400, 3000, 3600, and 4200 to produce micronized starch powder. The changes in structural and functional properties of the starch after jet milling process are studied. The particle size of starch significantly (p < 0.05) decreases after jet milling and as the classifier frequency increases. Also, the bulk and tap density decreases; while the specific surface area increases and the flowability of the milled samples becomes quite poor as the classifier frequency increases. The microscopy analysis shows that the jet milling destroys the crystalline areas and promotes amorphous areas of starch granules. The micronized starch samples show a significant (p < 0.05) increase in their water solubility, swelling power, water and fat holding capacities, and pasting temperature compared with native starch. However, a decrease in viscosity parameters of starch is found after jet milling and as classifier frequency increases. The initial moisture content of starch shows a slight effect on the functional properties of the micronized starch. The obtained results suggest that modified starch can be produced by fluidized bed jet milling.

Encapsulation and antioxidant activity of ascorbyl palmitate with normal and high amylose maize starch by spray drying

Amylose-lipid complexes can be formed by interaction between amylose and lipid as ligands. This study determines the effects of ascorbyl palmitate (0, 15, 50, 100, and 200 mg/g starch) on the functional properties of maize starches (normal and high amylose maize starch), amount of ascorbyl palmitate bound, release of ascorbyl palmitate after enzymatic hydrolysis and ascorbyl palmitate antioxidant activity after spray drying. Spray drying of starches (normal maize starch and high amylose maize starch) with ascorbyl palmitate at 185 °C resulted in the formation of type I amylose-lipid complexes. Entrapment of ascorbyl palmitate in the starch matrix also occurred during spray drying, and this was observed with confocal laser scanning microscopy (CLSM) micrographs. As expected, more ascorbyl palmitate bound with high amylose maize starch than normal maize starch. Less than 40% of the bound ascorbyl palmitate to high amylose maize starch was released during pancreatic α-amylase hydrolysis suggesting that some of the complexes were indigestible and can be fermented in the large intestine. The antioxidant activities of the ascorbyl palmitate highly correlated (R = 0.97) to the amount released during enzymatic hydrolysis. It can be concluded that spray drying of maize starches can be used to encapsulate ascorbyl palmitate to form amylose-lipid complexes with a higher amount of ascorbyl palmitate bound with maize starches when spray dried compared to pasting method as previously reported.

Tea polyphenols enhance binding of porcine pancreatic α-amylase with starch granules but reduce catalytic activity

The effects of tea polyphenols on binding of porcine pancreatic α-amylase (PPA) with normal maize starch granules were studied through solution depletion assays, fluorescence spectroscopy and initial rate kinetics. Only polyphenols which have inhibitory activity against PPA increased the binding of PPA with starch. The results are consistent with a binding equilibrium between polyphenols, starch and PPA. The dissociation constant (Kd) for PPA binding was decreased by tea polyphenols, with the effects greater for theaflavins than catechins and for galloylated than non-galloylated polyphenols. Tea polyphenols were also shown to increase the binding rate of PPA to starch. In addition, there were positive linear correlations between 1/Kd and reciprocal of competitive inhibition constant (1/Kic) and between 1/Kd and fluorescence quenching constant (KFQ). Despite the greater amount of PPA on the granules, starch hydrolysis is reduced because the polyphenol inhibition of PPA persists after binding to starch.

Role of entanglement concentration in dynamic viscoelasticity and film-forming property of cereal starches

Entanglement concentration (ce, w/v) means the onset of overlap and interpenetration of random-coil chains in a macromolecule solution. The effects of ce on the dynamic viscoelasticity and film-forming property of cereal starches were investigated. The results showed that ce affected significantly the ratio of crystalline to amorphous regions of normal rice starch, waxy rice starch, normal maize starch and wheat starch because the absorbance ratio (1047cm−1/1022cm−1) increased more obviously at concentrations increasing from 0.1% to ce. Storage modulus increased faster than loss modulus with increasing frequency. The presence of lower entanglement density and stronger mobility of the chain segments in normal rice starch due to the highest crossover, whereas the contrary is the case for waxy rice starch. But, no crossover point occurred in four cereal starch dispersions at concentrations <ce. The normal maize and wheat starch dispersions at concentrations around ce showed a Newtonian behaviour at low angular frequency, whereas it exhibited a shear-thinning behaviour at higher frequency. The normal rice and waxy rice starch dispersions exhibited a shear-thinning behaviour throughout the entire frequency. Four cereal starch films could only develop at concentrations ≥ce. Comparatively, wheat and normal rice starches had good filming properties.

Physicochemical properties of maize and sweet potato starches in the presence of cellulose nanocrystals

The goal of this research was to evaluate the effect of cellulose nanocrystals (CNC) on the gelatinization, pasting, and short- and long-term retrogradation properties of normal maize starch (NMS), waxy maize starch (WMS), and sweet potato starch (SPS). Differential scanning calorimetry (DSC) data indicated that the addition of CNC did not significantly change the gelatinization temperatures of starch, but the enthalpy change values slightly decreased. Rapid visco-analyzer (RVA) data suggested that CNC slightly increased the peak viscosity of NMS and SPS, while it reduced the setback values of SPS, indicating the retardation of short-term SPS retrogradation. Further, the dynamic time sweep of starches with CNC demonstrated remarkable inhibition of the short-term retrogradation of NMS and SPS. DSC results showed that 10% (w/w, based on starch) addition of CNC significantly (p < 0.05) decreased the retrogradation enthalpy change of NMS, WMS, and SPS. X-ray diffraction (XRD) results exhibited that the relative crystallinity of retrograded NMS, WMS, and SPS decreased as the content of CNC increased. Both DSC and XRD results suggested that there was really a dominant inhibiting influence of CNC on the recrystallization of amylopectin, and thus, the long-term retrogradation of starch was hindered. It could therefore be concluded that CNC apparently inhibited not only the short-term retrogradation of amylose, but also the long-term retrogradation of amylopectin.

Comparative Structural Characterization of Spiral Dextrin Inclusion Complexes with Vitamin E or Soy Isoflavone

In this study, the preparation and structural properties of spiral dextrin (SD)/vitamin E and SD/soy isoflavone inclusion complexes were studied. SD was obtained from debranched normal maize starch using isoamylases. After fractionation using a novel method of gradient ethanol precipitation, SD was separated into different fractions, among which SD-40 was found to be the optimal host molecule to prepare SD inclusion complexes with vitamin E or soy isoflavone. X-ray diffraction (XRD) and 13C cross-polarization magic angle spinning nuclear magnetic resonance (NMR) suggested that the crystalline structures of SD-40/vitamin E and SD-40/soy isoflavone were V6II and V6III types, respectively. Small-angle X-ray scattering revealed that the SD-40/vitamin E inclusion complex formed a tighter and more compact crystallite than the SD-40/soy isoflavone inclusion complex. Furthermore, the connection structures of inclusion complexes were investigated by two-dimensional nuclear Overhauser effect spectroscopy NMR, indicating that part of vitamin E with an alkyl chain was encapsulated in the helix cavity of SD-40, whereas the aromatic ring B of the soy isoflavone molecule was complexed by the helix cavity and screw of SD.

Effect of frying on the pasting and rheological properties of normal maize starch

Normal maize starch (NMS) with various water content was subjected to high temperature in the oil phase to mimic the frying process. The structure and physicochemical properties of the fried starchy samples were investigated. Frying induced the reduction in the swelling power, solubility, the amount of leached amylose, and the molecular weight of starch. Rapid visco-analysis (RVA) revealed the partial gelatinization and limited swelling of starch granules after frying treatment. The effect of frying on the pasting properties of starch was dependent on the water content. Creep curves were fitted with the Burgers model and results showed that the fried samples exhibited higher values of instantaneous creep compliance (J0) and viscoelastic creep compliance (Jm), whereas lower values of zero-shear viscosity (η0) as compared with those of native NMS. The low storage modulus (G′) and low loss modulus (G″) form dynamic viscoelasticity measurements indicated that the fried starch pastes exhibited viscoelastic properties that are inferior to those of native NMS paste. Flow state tests showed that fried starch pastes were less thixotropic than was native NMS. Present work confirmed the inhibitory effect of frying on starch granule swelling and starch molecules leaching. The formation of gelatinization layer near the surface of starch granules and the possible molecular degradation during frying were hypothesized to be responsible for the alterations of the pasting and rheological properties of starch.

Structural changes of waxy and normal maize starches modified by heat moisture treatment and their relationship with starch digestibility

In the present study, the variations in structure of waxy and normal maize starches modified by heat-moisture treatment (HMT) for different treating time (3h and 9h) were investigated. HMT caused the destruction of starch granules. The 1H NMR confirmed that glycosidic bonds were broken during HMT. The 13C NMR result suggested that HMT caused the transformation of starch granules from double and single helical components into amorphous components. Heat-moisture treated starches exhibited higher gelatinization temperature (To, Tp and Tc), narrower gelatinization temperature range (Tc-To) and lower gelatinization enthalpy (ΔH). HMT caused the rearrangement of starch molecules, degeneration of double helices and formation of new single helix. In addition, in vitro digestibility assessment indicated that the contents of rapidly digestible starch (RDS) and slowly digestible starch (SDS) were improved and resistant starch (RS) was reduced after HMT, which was related to the decrease of single and double helical components.

Effect of high pressure on rheological and thermal properties of quinoa and maize starches

Quinoa starch has small granules with relatively low gelatinization temperatures and amylose content. High hydrostatic pressure (HHP) is a non-thermal technique for food processing. In this study, effects of HHP up to 600MPa on physical properties of quinoa starch were studied and compared with those of a normal maize starch. Both starches gelatinized at 500 and 600MPa. The pressure of 600MPa completely gelatinized quinoa starch as revealed by thermal analysis. Dynamic rheological analysis showed that HHP improved the gel stability of both starches during cooling. HHP had little effects on amylopectin recrystallization and gel textural properties of starch. Overall, quinoa starch was more susceptible to HHP than maize starch. The effects of HHP on some rheological properties such as frequency dependence were different between these two types of starches. The differences could be attributed to the different composition, granular and chemical structures of starch, and the presence of granule remnants.

Starch nanoparticles resulting from combination of dry heating under mildly acidic conditions and homogenization

To modify starch granular structure, normal maize starch was subjected to dry heating with various amounts of 1.0M HCl (1.2, 1.4 or 1.6mL) and different treatment times (2, 4 or 8h). For all reaction conditions, at least 80% of the starch substance was recovered, and amylose and amylopectin B1 chains were preferentially cleaved. As acidic condition and/or treatment time increased, the treated granules were readily fragmented by homogenization. The treatment appeared to alter short-range crystalline structure (FT-IR), but long-range crystalline structure (XRD) remained intact. Homogenization for 60min fragmented the treated starch granules (subjected to reaction condition of 1.4mL/4h, 1.6mL/2h, and 1.6mL/4h) into nanoparticles consisting of individual platelet-like and spherical particles with diameters less than 100nm. However, the fragmentation caused obvious damage in the long-range crystalline structure of starch nanoparticles, while the short-range chain associations remained relatively intact.

Effect of acid-ethanol treatment and debranching on the structural characteristics and digestible properties of maize starches with different amylose contents

In this study, maize starches with different amylose contents were modified by acid-ethanol treatment (AET) to various degrees, followed by debranching and then recrystallization through temperature cycling to produce resistant starch type III (RS3). The structural characteristics and digestible properties of the AET-debranched starches were investigated. The result indicated significant reductions in amylose and long side-chain length in high-amylose maize starch (HMS) and normal maize starch (NMS), but minor variations in the chain-length distribution in waxy maize starch (WMS). All three maize starches exhibited increased relative crystallinities and RS levels following moderate AET; however, the increment varied according to starch types. The highest RS contents of HMS, NMS, and WMS at 66.8%, 58.7%, and 68.4% were obtained after 8 h, 24 h, and 14 h of AET, respectively. These results indicated that the appropriate reduction in chain length following AET and prior to debranching was beneficial to RS3 formation.

Effect of hydrocolloids and salts on retrogradation of native and modified maize starch

Retrogradation of native and hydroxypropylated normal maize starch heated in water in the presence or absence of hydrocolloids or the water-soluble polymer poly (ethylene glycol) was investigated. Results were compared both with the effects of no added hydrocolloid and with the effects of added salts known to be retrogradation promoters or inhibitors. Development of solution turbidity was used as the indicator of retrogradation. Chaotropic ions were the most effective in reducing retrogradation. Kosmotropic ions were the most effective in promoting retrogradation. Granule swelling and disintegration and dissolution of starch polymer molecules was inhibited by sulfate and citrate ions, xanthan, and guar gum. The hydrophilicity or hydrophobicity of hydrocolloid molecules may influence their effect on retrogradation. Dissolved substances may have an effect on hydration and solubility of hydroxypropylated starch molecules.

The effects of entanglement concentration on the hydrodynamic properties of cereal starches.

The hydrodynamic properties of four cereal starches in dilute and semi-dilute aqueous solutions were investigated using an Ubbelohde viscometer, a transmission electron microscope and steady shear rheological measurements. The results indicated that the starch solutions showed the nonlinear shape of the ηsp /c versus c curves in dilute solutions, followed by a linear increase to different extents thereafter. The intrinsic viscosity might be positively correlated with the entanglement concentration (ce ). Compared to normal maize and wheat starch solutions, ce influences more significantly the network formation of normal and waxy rice starch solutions. At concentrations ≤ ce , the gelatinized cereal starch solutions hardly exhibit shear thinning behavior, whereas shear thinning behavior developed at concentrations > ce , at which the solutions were pseudoplastic and thixotropic. The obtained information will be very useful, based on ce as a reference value, in regulating the starch concentration suitable for different industrial applications. © 2016 Society of Chemical Industry.